Working Over Time: Dynamic Inconsistency in Real E ort Tasks · formance, temptation, and...

Working Over Time: Dynamic Inconsistency in RealEffort Tasks ∗

Ned Augenblick †

UC Berkeley, Haas School of Business

Muriel Niederle‡

Stanford University and NBER

Charles Sprenger§

Stanford University

First Draft: July 15, 2012This Version: January 26, 2015

Abstract

Experimental tests of dynamically inconsistent time preferences have largely reliedon choices over time-dated monetary rewards. Several recent studies have failed to findthe standard patterns of present bias. However, such monetary studies contain often-discussed confounds. In this paper, we sidestep these confounds and investigate choicesover consumption (real effort) in a longitudinal experiment. We pair this effort study witha companion monetary discounting study. We confirm very limited time inconsistencyin monetary choices. However, subjects show considerably more present bias in effort.Furthermore, present bias in the allocation of work has predictive power for demandof a meaningfully binding commitment device. Therefore our findings validate a keyimplication of models of dynamic inconsistency, with corresponding policy implications.

JEL classification: C91, D12, D81

Keywords : Time Discounting, Demand for Commitment, Real Effort, Convex Time Budget

∗We are grateful for many helpful discussions including those of Steffen Andersen, James Andreoni, ColinCamerer, Yoram Halevy, David Laibson, Matthew Rabin, and Georg Weizsacker. We thank Wei Wu for helpfulresearch assistance and technological expertise.†University of California Berkeley, Haas School of Business, University of California, Berkeley, 545 Student

Services Building, 1900, Berkeley, CA, 94720-1900. [email protected]‡Stanford University, Department of Economics, Landau Economics Building, 579 Serra Mall, Stanford, CA

94305; [email protected], www.stanford.edu/∼niederle§Stanford University, Department of Economics, Landau Economics Building, 579 Serra Mall, Stanford, CA

94305; [email protected].

1 Introduction

Models of dynamically inconsistent time preferences (Strotz, 1956; Laibson, 1997; O’Donoghue

and Rabin, 1999, 2001) are a pillar of modern behavioral economics, having added generally to

economists’ understanding of the tensions involved in consumption-savings choices, task per-

formance, temptation, and self-control beyond the standard model of exponential discounting

(Samuelson, 1937). Given the position of present-biased preferences in the behavioral litera-

ture, there is clear importance in testing the model’s central falsifiable hypothesis of diminishing

impatience through time. Further, testing auxiliary predictions such as sophisticated individu-

als’ potential to restrict future activities through commitment devices can distinguish between

competing accounts for behavior and deliver critical prescriptions to policy makers.1 In this

paper we present a test of dynamic inconsistency in consumption and investigate the demand

for a meaningfully binding commitment device.

To date, a notably large body of laboratory research has focused on identifying the shape

of time preferences (for a comprehensive review to the early 2000s, see Frederick, Loewenstein

and O’Donoghue, 2002). The core of this experimental literature has identified preferences

from time-dated monetary payments.2 Several confounds exist for identifying the shape of

time preferences from such monetary choices. Issues of payment reliability and risk preference

suggest that subject responses may be closely linked to their assessment of the experimenter’s

reliability rather than solely their time preferences.3 Furthermore, monetary payments may not

1Sophistication is taken to mean the decision-maker’s recognition (perhaps partial recognition) of his predilec-tion to exhibit diminishing impatience through time. Appendix section A outlines the model which follows theframework of O’Donoghue and Rabin (2001).

2Recent efforts using time dated monetary payments to identify time preferences include Ashraf, Karlan andYin (2006), Andersen, Harrison, Lau and Rutstrom (2008), Dohmen, Falk, Huffman and Sunde (2010), Tanaka,Camerer and Nguyen (2010), Benjamin, Choi and Strickland (2010) Voors, Nillesen, Verwimp, Bulte, Lensinkand van Soest (2012), Bauer, Chytilova and Morduch (2012), Sutter, Kocher, Glatzle-Ruetzler and Trautmann(2013), and Dupas and Robinson (2013).

3This point was originally raised by Thaler (1981) who, when considering the possibility of using incentivizedmonetary payments in intertemporal choice experiments noted ‘Real money experiments would be interesting butseem to present enormous tactical problems. (Would subjects believe they would get paid in five years?)’. Recentwork validates this suspicion. Andreoni and Sprenger (2012a), Gine, Goldberg, Silverman and Yang (2010),and Andersen, Harrison, Lau and Rutstrom (2012) all document that when closely controlling transactionscosts and payment reliability, dynamic inconsistency in choices over monetary payments is virtually eliminatedon aggregate. Further, when payment risk is added in an experimentally controlled way, non-expected utility

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be suitable to identify parameters of models defined over time-dated consumption. Arbitrage

arguments imply that choices over monetary payments should only reveal subjects’ borrowing

and lending opportunities (Cubitt and Read, 2007).4 Chabris, Laibson and Schuldt (2008)

describe the difficulty in mapping experimental choices over money to corresponding model

parameters, casting skepticism over monetary experiments in general.

In this paper we attempt to move out of the domain of monetary choice and into the

domain of consumption. Our design delivers precise point estimates on dynamic inconsistency

based upon intertemporal allocations of effort and provides an opportunity to link parameter

measures with demand for commitment. Delivering such a connection and contrasting present

bias measured over money and over consumption are key contributions of our study.

There are few other experimental tests of dynamic inconsistency in consumption. Lead-

ing examples document dynamic inconsistency in brief, generally a few minutes, intertemporal

choices over irritating noises and squirts of juice and soda (Solnick, Kannenberg, Eckerman and

Waller, 1980; McClure, Laibson, Loewenstein and Cohen, 2007; Brown, Chua and Camerer,

2009). On a larger time scale, perhaps closer to everyday decision-making, there are two key

contributions. Read and van Leeuwen (1998) identify dynamic inconsistency between choices

over snack foods made one week apart. Ariely and Wertenbroch (2002) document demand

risk preferences deliver behavior observationally equivalent to present bias as described above (Andreoni andSprenger, 2012b).

4In a monetary discounting experiment, subjects often make binary choices between a smaller sooner pay-ment, $X, and a larger later payment, $Y. The ratio, YX , defines a lab-offered gross interest rate. An individualwho can borrow at a lower rate than the lab-offered rate should take the larger later payment, finance anysooner consumption externally, and repay their debts with the later larger payment they chose. An individualwho can save at a higher rate than the lab-offered rate should take the smaller sooner payment, pay for anysooner consumption and place the remainder in their savings vehicle. These two strategies deliver a budgetconstraint that dominates the lab-offered budget constraint. Hence, monetary discounting experiments shouldreveal only external borrowing and lending opportunities. And, unless such opportunities change over time,one should reveal no present bias. The logic extends to the convex decisions of Andreoni and Sprenger (2012a).Subjects should allocate only at corner solutions and such solutions should maximize net present value at exter-nal interest rates. This point has been thoughtfully taken into account in some studies. For example, Harrison,Lau and Williams (2002) explicitly account for potential arbitrage in their calculations of individual discountrates by measuring individual borrowing and saving rates and incorporating these values in estimation. Cubittand Read (2007) provide excellent recent discussion of the arbitrage arguments and other issues for choices overmonetary payments. One counterpoint is provided by Coller and Williams (1999), who present experimentalsubjects with a fully articulated arbitrage argument and external interest rate information and document onlya small treatment effect.

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for deadlines for classroom and work assignments, a potential sign of commitment demand for

dynamically inconsistent individuals. Though suggestive, neither exercise allows for precise

identification of discounting parameters, nor delivers the critical linkage between present bias

and commitment demand. With the exception of Ashraf et al. (2006) and Kaur, Kremer and

Mullainathan (2010) virtually no research attempts to make such links. Ashraf et al. (2006)

employ monetary discounting measures and link them to take-up of a savings commitment

product. Kaur et al. (2010) use disproportionate effort response on paydays to make inference

on dynamic inconsistency and link this behavior to demand for a dominated daily wage con-

tract. There are several major differences between our research and this prior work, which are

discussed in detail in Section 3.4. Most important is the measurement of dynamic inconsistency.

As opposed to monetary measures or measuring potential correlates of present bias, our effort

allocations yield precise parametric measures linked directly to the theory of present bias.

102 UC Berkeley students participated in a seven week longitudinal experiment. Subjects

allocated units of effort (i.e., negative leisure consumption) over two work dates. The tasks over

which subjects made choices were transcription of meaningless Greek texts and completion of

partial Tetris games. Allocations were made at two points in time: an initial allocation made in

advance of the first work date and a subsequent allocation made on the first work date. We then

randomly selected either an initial allocation or a subsequent allocation and required subjects

to complete the allocated tasks. This incentivized all allocation decisions. Differences between

initial and subsequent allocations allow for precise measurement of dynamic inconsistency. A

first block of the experiment, three weeks in length, was dedicated to this measurement effort.

In a second block of the experiment, also three weeks in length, the design was augmented

to elicit demand for a commitment device. The commitment device of the second block allowed

subjects to probabilistically favor their initial allocations over their subsequent allocations in the

random selection process. Hence, commitment reveals a subject’s preference for implementing

the allocations made in advance of the first work date. We investigate demand for our offered

commitment device and correlate identified dynamic inconsistency with commitment demand.

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The repeated interaction of our seven-week study allows us to complement measures of

effort discounting with measures of monetary discounting taken from Andreoni and Sprenger

(2012a) Convex Time Budget (CTB) choices over cash payments received in the laboratory. In

these choices, subjects allocated money over two dates. Variation in whether the first payment

date is the present delivers identification of monetary present bias. Hence, we can compare

dynamic inconsistency measured over work and money at both the aggregate and individual

level within subjects. A second study, essentially a between-subjects replication exercise, was

also conducted to provide corroboration of the within-subject conclusions.

We document three primary findings. First, in the domain of money we find virtually no

evidence of present bias. Monetary discount rates involving present dates are effectively indis-

tinguishable from those involving only future dates. Further, subjects appear to treat money

received at different times as perfect substitutes, suggesting they treat money as fungible. Sec-

ond, in the domain of effort we find significant evidence of present bias. Subjects allocate

roughly nine percent more work to the first work date when the allocation of tasks is made in

advance compared to when it is made on the first work date itself. Corresponding parameter

estimates corroborate these non-parametric results. Discount rates measured in advance of the

first work date are around zero percent per week while discount rates measured on the first

work date are around eleven percent per week. We reproduce these two primary study results

in our between-subjects replication exercise with an additional 200 UC Berkeley students. Our

third finding is that 59 percent of subjects demand commitment at price $0, preferring a higher

likelihood of implementing their initial pre-work date allocations. We show that the choice

of commitment is binding and meaningful in the sense that initial preferred allocations differ

significantly from subsequent allocations for committing subjects. Importantly, we show that

present bias measured in the first block of the experiment is predictive of this (later) commit-

ment choice. A corresponding investigation on the extent of sophistication and commitment

demand indicates that subjects potentially forecast their present bias. This link delivers key

validation and support for our experimental measures and well-known theoretical models of

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present bias.

We draw two conclusions from our results. First, our results show evidence of present bias

in the domain of consumption with a design that eliminates a variety of potential confounds

and provides precise parameter estimation. Second, our subjects are at least partially aware of

their dynamic inconsistency as they demand binding commitment.

The paper proceeds as follows: Section 2 provides details for our longitudinal experimental

design. Section 3 presents results and section 4 concludes.

2 Design

To examine dynamic inconsistency in real effort, we introduce a longitudinal experimental

design conducted over seven weeks. Subjects are asked to initially allocate tasks, subsequently

allocate tasks again, and complete those tasks over two work dates. Initial allocations made

in advance of the first work date are contrasted with subsequent allocations made on the first

work date to identify dynamic inconsistency.

If all elements of the experiment are completed satisfactorily, subjects receive a completion

bonus of $100 in the seventh week of the study. Otherwise they receive only $10 in the seventh

week. The objective of the completion bonus is to fix the monetary dimension of subjects’

effort choices and to ensure a sizable penalty for attrition. Subjects are always paid the same

amount for their work, the question of interest is when they prefer to complete it.

We present the design in five subsections. First, we describe the Jobs to be completed.

Second, we present a timeline of the experiment and the decision environment in which alloca-

tions were made. The third subsection describes the elicitation of commitment demand. The

fourth subsection addresses design details including recruitment, selection, and attrition. The

fifth subsection presents the complementary monetary discounting study. In addition to this

primary within-subjects study, we also conducted a between-subjects replication exercise. The

between-subjects design is discussed primarily in section 3.5 and note is made of any design

differences.

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2.1 Jobs

The experiment focuses on intertemporal allocations of effort for two types of job. In Job 1,

subjects transcribe a meaningless Greek text through a computer interface. Panel A of Figure

1 demonstrates the paradigm. Random Greek letters appear, slightly blurry, in subjects’ tran-

scription box. By pointing and clicking on the corresponding keyboard below the transcription

box, subjects must reproduce the observed series of Greek letters. One task is the completion

of one row of Greek text with 80 percent accuracy.5 In the first week, subjects completed a

task from Job 1 in an average of 54 seconds. By the final week, the average was 46 seconds.

In Job 2, subjects are asked to complete four rows of a modified Tetris game, see Panel B

of Figure 1. Blocks of random shapes appear at the top of the Tetris box and fall at a fixed

relatively slow speed. Arranging the shapes to complete a horizontal line of the Tetris box is

the game’s objective. Once a row is complete, it disappears and the shapes above fall into

place. One task is the completion of four rows of Tetris. If the Tetris box fills to the top with

shapes before the four rows are complete, the subject begins again with credit for the rows

already completed. In the first week, subjects completed a task from Job 2 in an average of 55

seconds. By the final week, the average was 46 seconds. In contrast to a standard Tetris game,

one cannot accelerate the speed of the falling shapes, and one does not pass through ‘levels’ of

progressive difficulty. Hence, our implementation of Tetris should not be thought of as being

as enjoyable as the real thing.

2.2 Experimental Timeline

The seven weeks of the experiment are divided into two blocks. Weeks 1, 2, and 3 serve as the

first block. Weeks 4, 5, and 6 serve as the second block. Week 7 occurs in the laboratory and is

only used to pay subjects. Subjects always participate on the same day of the week throughout

5 Our measure of accuracy is the Levenshtein Distance. The Levenshtein Distance is commonly used incomputer science to measure the distance between two strings and is defined as the minimum number of editsneeded to transform one string into the other. Allowable edits are insertion, deletion or change of a singlecharacter. As the strings of Greek characters used in the transcription task are 35 characters long our 80percent accuracy measure is equivalent to 7 edits or less or a Levenshtein Distance ≤ 7.

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Figure 1: Experimental Jobs

Panel A: Job 1- Greek Transcription

Panel B: Job 2- Partial Tetris Games

the experiment. That is, subjects entering the lab on a Monday allocate tasks to be completed

on two future Monday work dates. Therefore, allocations are made over work dates that are

always exactly seven days apart.

Weeks 1 and 4 occur in the laboratory and subjects are reminded of their study time the

night before. Weeks 2, 3, 5, and 6 are completed online. For Weeks 2, 3, 5, and 6, subjects

are sent an email reminder at 8pm the night before with a (subject-unique) website address.

Subjects are required to log in to this website between 8am and midnight of the day in question

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and complete their work by 2am the following morning.

At each point of contact, subjects are first given instructions about the decisions to be

made and work to be completed that day, reminded of the timeline of the experiment, given

demonstrations of any unfamiliar actions, and then asked to complete the necessary actions.

The second block of the experiment, Weeks 4, 5, and 6, mimics the first block of Weeks

1, 2, and 3, with one exception. In Week 4, subjects are offered a probabilistic commitment

device, which is described in detail in subsection 2.4. Hence, we primarily describe Weeks 1,

2 and 3 and note any design changes for Weeks 4, 5 and 6. To summarize our longitudinal

effort experiment, Table 1 contains the major events in each week which are described in detail

below.

Table 1: Summary of Longitudinal Experiment

10 Effort Minimum Allocation-That- Complete Commitment ReceiveAllocations Work Counts Chosen Work Choice Payment

Week 1 (In Lab): x xWeek 2 (Online): x x x xWeek 3 (Online): x xWeek 4 (In Lab): x x xWeek 5 (Online): x x x xWeek 6 (Online): x xWeek 7 (In Lab): x

2.3 Effort Allocations

In Week 1, subjects allocate tasks between Weeks 2 and 3. In Week 2, subjects also allocate

tasks between Weeks 2 and 3. Subjects were not reminded of their initial Week 1 allocations in

Week 2. Note that in Week 1 subjects are making decisions involving two future work dates,

whereas in Week 2, subjects are making decisions involving a present and a future work date.

Before making decisions in Week 1, subjects are told of the Week 2 decisions and are aware

that exactly one of all Week 1 and Week 2 allocation decisions will be implemented.

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2.3.1 Allocation Environment

Allocations are made in a convex environment. Using slider bars, subjects allocate tasks to

two dates, one earlier and one later, under different interest rates.6 Figure 2 provides a sample

allocation screen. To motivate the intertemporal tradeoffs faced by subjects, decisions are

described as having different ‘task rates.’ Every task allocated to the later date reduces the

number of tasks allocated to the sooner date by a stated number. For example, a task rate of

1:0.5 implies that each task allocated to Week 3 reduces by 0.5 the number in Week 2.7

For each task and for each date where allocations were made, subjects faced five task rates.

These task rates take the values, R ∈ {0.5, 0.75, 1, 1.25, 1.5}. The subjects’ decision can be

formulated as allocating tasks e over times t and t+k, et and et+k, subject to the present-value

budget constraint,

et +R · et+k = m. (1)

The number of tasks that subjects could allocate to the sooner date was capped at fifty such

that m = 50 in each decision in the experiment.8

2.3.2 Minimum Work

In each week, subjects are required to complete 10 tasks of each Job prior to making allocation

decisions or completing allocated tasks. The objective of these required tasks, which we call

“minimum work,” is three-fold. First, minimum work requires a few minutes of participation

at each date, forcing subjects to incur the transaction costs of logging on to the experimental

website at each time.9 Second, minimum work, especially in Week 1, provides experience for

6The slider was initially absent from each slider bar and appeared in the middle of the bar once a subjectclicked on the allocation. Every slider bar was thus clicked on before submission, avoiding purely passiveresponse.

7We thank an anonymous referee for noting a small error in our instructions which inverted the task rateswhen first introducing them. Though this appears not to have affected response as allocations move appropri-ately with task rates, we do correct this error in our replication exercise and document very similar behavior.See section 3.5 for detail.

8We use R for present value budget constraints of the form et +R · et+k = m, and P for future value budgetconstraints of the form P · et + et+k = m.

9A similar technique is used in monetary discounting studies where minimum payments are employed toeliminate subjects loading allocations to certain dates to avoid transaction costs of receiving multiple payments

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Figure 2: Convex Allocation Environment

subjects such that they have a sense of how effortful the tasks are when making their allocation

decisions. Third, we require minimum work in all weeks before all decisions, and subjects are

informed that they will have to complete minimum work at all dates. This ensures that subjects

have experienced and can forecast having experienced the same amount of minimum work when

making their allocation decisions at all points in time.

2.3.3 The Allocation-That-Counts

Each subject makes 20 decisions allocating work to Weeks 2 and 3: five decisions are made

for each Job in Week 1 and five for each Job in Week 2. After the Week 2 decisions, one of

these 20 allocations is chosen at random as the ‘allocation-that-counts’ and subjects have to

complete the allocated number of tasks on the two work dates to ensure successful completion

of the experiment (and hence payment of $100 instead of only $10 in Week 7).

The randomization device probabilistically favors the Week 2 allocations over the Week 1

allocations. In particular, subjects are told (from the beginning) that their Week 1 allocations

will be chosen with probability 0.1, while their Week 2 allocations will be chosen with probability

or cashing multiple checks (Andreoni and Sprenger, 2012a).

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0.9. Within each week’s allocations, every choice is equally likely to be the allocation-that-

counts.10 This randomization process ensures incentive compatibility for all decisions. This

design choice was made for two reasons. First, it increases the chance that subjects experienced

their own potentially present-biased behavior. Second, it provides symmetry to the decisions

in Block 2 that elicit demand for commitment.

2.4 Commitment Demand

In the second block of the experiment, Weeks 4, 5, and 6, subjects are offered a probabilistic

commitment device. In Week 4, subjects are given the opportunity to choose which allocations

will be probabilistically favored. In particular, they can choose whether the allocation-that-

counts comes from Week 4 with probability 0.1 (and Week 5 with probability 0.9), favoring

flexibility, or from Week 4 with probability 0.9, favoring commitment. This form of commitment

device was chosen because of its potential to be meaningfully binding. Subjects who choose to

commit and who differ in their allocation choices through time can find themselves constrained

by commitment with high probability.

In order to operationalize our elicitation of commitment demand, subjects are asked to

make 15 multiple price list decisions between two options. In the first option, the allocation-

that-counts will come from Week 4 with probability 0.1. In the second option, the allocation-

that-counts will come from Week 4 with probability 0.9. In order to determine the strength

of preference, an additional payment of between $0 and $10 is added to one of the options for

each decision.11 Figure 3 provides the implemented price list. One of the 15 commitment

decisions is chosen for implementation, ensuring incentive compatibility. Subjects are told that

the implementation of the randomization for the commitment decisions will occur once they

submit their Week 5 allocation decisions. Given this randomization procedure, an individual

choosing commitment in all 15 decisions will complete a Week 4 allocation with probability

10For the description of the randomization process given to subjects please see instructions in Appendix F.11We chose not to have the listed prices ever take negative values (as in a cost) to avoid subjects viewing

paying for commitment as a loss.

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0.9. Each row at which a subject chooses flexibility reduces this probability by 5.3 percent.12

Hence a subject choosing to commit at price zero (the eighth row) and lower will complete an

initial allocation with probability 0.53. Naturally, if subjects treat each commitment decision

in isolation, the incentives are more stark as each decision moves the probability of facing an

initial allocation from 0.1 to 0.9.13 This isolation is encouraged as subjects are told to treat

each decision as if it was the one going to be implemented (See Appendix F.4 for detail).

Figure 3: Commitment Demand Elicitation

Our commitment demand decisions, and the second block of the experiment, serve three

purposes. First, they allow us to assess the demand for commitment and flexibility. Second, a

key objective of our study is to explore the theoretical link, under the assumption of sophistica-

tion, between present bias and commitment demand. Are subjects who are present-biased more

likely to demand commitment? Third, a correlation between time inconsistency and commit-

ment validates the interpretation of present bias over other explanations for time inconsistent

choices. For example, a subject who has a surprise exam in Week 2 may be observationally

indistinguishable in her Week 2 effort choices from a present-biased subject. However, a subject

12Each row changes the probability of implementing an initial allocation by (1/15 * (0.9 - 0.1)) = 0.053.13In assessing the value of commitment we make this assumption, ignoring the second stage randomization

inherent to the commitment demand elicitation.

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prone to such surprises should favor flexibility to accommodate her noisy schedule. In contrast,

a sophisticated present-biased subject may demand commitment to restrict her future self.

2.5 Design Details

102 UC Berkeley student subjects were initially recruited into the experiment across 4 experi-

mental sessions on February 8th, 9th and 10th, 2012 and were told in advance of the seven week

longitudinal design and the $100 completion bonus.14 Subjects did not receive an independent

show up fee. 90 subjects completed all aspects of the working over time experiment and re-

ceived the $100 completion bonus. The 12 subjects who selected out of the experiment do not

appear different on either initial allocations, comprehension or a small series of demographic

data collected at the end of the first day of the experiment.15 One more subject completed

initial allocations in Week 1, but due to computer error did not have their choices recorded.

This leaves us with 89 subjects.

One critical aspect of behavior limits our ability to make inference for time preferences

based on experimental responses. In particular, if subjects have no variation in allocations in

response to changes in R in some weeks, then attempting to point identify both discounting and

cost function parameters is difficult, yielding imprecise and unstable estimates. In our sample,

nine subjects have this issue for one or more weeks of the study.16 For the analysis, we focus on

the primary sample of 80 subjects who completed all aspects of the experiment with positive

variation in their responses in each week. In Appendix Table A9, we re-conduct the aggregate

analysis including these nine subjects and obtain very similar findings.

14Student subjects were recruited from the subject pool of the UC Berkeley Experimental Laboratory, Xlab.Having subjects informed of the seven week design and payment is a potentially important avenue of selection.Our subjects were willing to put forth effort and wait seven weeks to receive $100. Though we have no formaltest, this suggests that our subjects may be a relatively patient selection.

153 of those 12 subjects dropped after the first week while the remaining 9 dropped after the second week.Including data for these 9 subjects where available does qualitatively alter the analysis or conclusions.

16Appendix Tables A5 and A6 provide estimates for each individual based on their Block 1 data. The9 individuals without variation in their responses in one or more weeks are noted. Extreme estimates areobtained for individuals without variation in experimental response in one of the weeks of Block 1.

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2.6 Monetary Discounting

Subjects were present in the laboratory in the first, fourth, and seventh week of the experiment.

This repeated interaction facilitates a monetary discounting study that complements our main

avenue of analysis. In Weeks 1 and 4 of our experimental design, once subjects complete their

allocation of tasks, they are invited to respond to additional questions allocating monetary

payments to Weeks 1, 4, and 7. In Week 1, we implement three Andreoni and Sprenger (2012a)

Convex Time Budget (CTB) choice sets, allocating payments across: 1) Week 1 vs. Week 4; 2)

Week 4 vs. Week 7 (Prospective); and 3) Week 1 vs. Week 7. Individuals allocate monetary

payments across the two dates t and t+ k, ct and ct+k, subject to the intertemporal constraint,

P · ct + ct+k = m. (2)

The experimental budget is fixed at m = $20 and five interest rates are implemented in each

choice set, summarized by P ∈ {0.99, 1, 1.11, 1.25, 1.43}. These values were chosen for compar-

ison with prior work (Andreoni and Sprenger, 2012a).17 In Week 4, we ask subjects to allocate

in a CTB choice set over Week 4 and Week 7 under the same five values of P . We refer to these

choices made in Week 4 as Week 4 vs. Week 7 and those made in Week 1 over these two dates

as Week 4 vs. Week 7 (Prospective). Hence, subjects complete a total of four CTB choice sets.

The CTBs implemented in Weeks 1 and 4 are paid separately and independently from the

rest of the experiment with one choice from Week 1 and one choice from Week 4 chosen to be

implemented. Subjects are paid according to their choices. Subjects are not told of the Week 4

choices in Week 1. As in Andreoni and Sprenger (2012a), we have minimum payments of $5 at

each payment date to ensure equal transaction costs in each week, such as waiting to get paid.

Appendix F provides the full experimental instructions.

While the monetary discounting experiment replicates the design of Andreoni and Sprenger

(2012a) to a large extent, there are two important differences. First, Andreoni and Sprenger

(2012a) implement choices with payment by check. Our design implements payment by cash

17Additionally, P = 0.99 allows us to investigate the potential extent of negative discounting.

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with potentially lower transaction costs. Second, Andreoni and Sprenger (2012a) implement

choices with present payment received only by 5:00 p.m. in a subject’s residence mailbox. If

these payments are not construed as the present, one would expect no present bias. Here, we

provide payment immediately in the lab.

In both Weeks 1 and 4, the monetary allocations are implemented after the more central

effort choices. The monetary choices were not announced in advance and subjects could choose

not to participate; five did so in either Weeks 1 or 4. In our analysis of monetary discounting,

we focus on the 75 subjects from the primary sample with complete monetary choice data.

3 Results

The results are presented in five subsections. First, we present aggregate results from the mone-

tary discounting study and compare our observed level of limited present bias with other recent

findings. Second, we move to effort related discounting and provide both non-parametric and

parametric aggregate evidence of present bias. Third, we analyze individual heterogeneity in

discounting for both work and money. Fourth we present results related to commitment de-

mand, documenting correlations with previously measured present bias and analyzing the value

of commitment. Lastly, a fifth subsection is dedicated to a between-subjects replication exer-

cise of the results concerning differences in discounting when comparing choices over monetary

rewards to effort chocies.

3.1 Monetary Discounting

Figure 4 presents the data from our monetary discounting experiment. The mean allocation

to the sooner payment date at each value of P from P · ct + ct+k = 20 is reported for the 75

subjects from the primary sample for whom we have all monetary data. The left panel shows

three data series for payments sets with three-week delay lengths while the right panel shows

the data series for the payment sets with a six-week delay length. Standard error bars are

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clustered at the individual level.

Figure 4: Monetary Discounting Behavior

05

1015

20

1 1.2 1.4 1 1.2 1.4

3 Week Delay 6 Week Delay

Week 1 vs. Week 4 Week 4 vs. Week 7 (Prospective)Week 4 vs. Week 7 Week 1 vs. Week 7SE

Dol

lars

Allo

cate

d to

Ear

ly D

ate

P(from Pct+ct+k=20)

Graphs by moneyk

We highlight two features of Figure 4. First, note that as P from P · ct + ct+k = 20

increases, the average allocation to the sooner payment decreases, following the law of demand.

Indeed, at the individual level 98% of choices are monotonically decreasing in P , and only

1 subject exhibits more than 5 non-monotonicities in demand in their monetary choices.18

This suggests that subjects as a whole understand the implied intertemporal tradeoffs and the

decision environment.

Second, Figure 4 allows for non-parametric investigation of present bias in two contexts.19

18Subjects have 16 opportunities to violate monotonicity comparing two adjacent values of P in their 20 totalCTB choices. 63 of 75 subjects have no identified non-monotonocities. Andreoni and Sprenger (2012a) providea detailed discussion of the extent of potential errors in CTB choices. In particular they note that prevalenceof non-monotonicities in demand are somewhat less than the similar behavior of multiple switching in standardMultiple Price List experiments.

19Though the six-week delay data are used in estimation, our non-parametric tests only identify present biasfrom choices over three-week delays. Without parametric assumptions for utility our data do not lend themselvesnaturally to the method of identifying present bias where short horizon choices are compared to long horizon

17

First, one can consider the static behavior, often attributed to present bias, of subjects being

more patient in the future than in the present by comparing the series Week 1 vs. Week

4 and Week 4 vs. Week 7 (Prospective). In this comparison, controlling for P , subjects

allocate on average $0.54 (s.e = 0.31) more to the sooner payment when it is in the present,

F (1, 74) = 2.93, (p = 0.09). A second measure of present bias is to compare Week 4 vs. Week 7

(Prospective) made in Week 1 to the Week 4 vs. Week 7 choices made in Week 4. This measure

is similar to the recent work of Halevy (2012). Ignoring income effects associated with having

potentially received prior payments, this comparison provides a secondary measure of present

bias. In this comparison, controlling for P , subjects allocate on average $0.47 (s.e = 0.32) more

to the sooner payment when it is in the present, F (1, 74) = 2.08, (p = 0.15).20 Table 2, Panel

A provides a corresponding tabulation of behavior, presenting the budget share allocated to

the sooner payment date and the proportion of choices that can be classified as present-biased.

Budget shares for the sooner payment are calculated as (P · ct)/m for each allocation. Across

all values of P subjects allocate around 38% (s.e. = 1.73) of their experimental budget to the

sooner payment date when the sooner date is in the future (t 6= 0) and around 41% (1.34) to the

sooner payment date when the sooner date is in the present (t = 0), F (1, 74) = 3.50, (p = 0.07).

Further, across all values of P , seventy-eight percent of choices are dynamically consistent, 13%

are present-biased, and 9% are future-biased.

We find limited non-parametric support for the existence of a present bias over mone-

tary payments. To provide corresponding estimates of present bias we follow the parametric

assumptions of Andreoni and Sprenger (2012a) and assume quasi-hyperbolic (Laibson, 1997;

O’Donoghue and Rabin, 2001) power utility with Stone-Geary background parameters. Hence,

the quasi-hyperbolic discounted utility from experimental payments at two dates, ct, received

choices to examine whether discount factors nest exponentially (see, for example Kirby, Petry and Bickel, 1999;Giordano, Bickel, Loewenstein, Jacobs, Marsch and Badger, 2002).

20Additionally, this measure is close in spirit to our effort experiment where initial allocations are compared tosubsequent allocations. To get a sense of the size of potential income effects, we can also compare the Week 1 vs.Week 4 choices made in Week 1 to the Week 4 vs. Week 7 choices made in Week 4. Controlling for P , subjectsallocate on average $0.07 (s.e = 0.31) more to the sooner payment in Week 1, F (1, 74) = 0.05, (p = 0.82),suggesting negligible income effects.

18

Table 2: Aggregate Behavior By Interest Rate

Panel A: Monetary Choices

P t 6= 0 t = 0 t-test Proportion Proportion ProportionBudget Share Budget Share (p-value) Present-Biased Dynamically Consistent Future-Biased

(1) (2) (3) (4) (5) (6)

0.952 0.924 0.923 0.07 0.073 0.813 0.113(0.228) (0.189) (p=0.94)

1 0.774 0.813 1.32 0.200 0.660 0.140(0.368) (0.323) (p=0.19)

1.11 0.102 0.148 1.86 0.180 0.733 0.087(0.259) (0.300) (p=0.06)

1.25 0.051 0.087 1.97 0.113 0.853 0.033(0.177) (0.239) (p=0.05)

1.429 0.053 0.077 1.40 0.100 0.847 0.053(0.182) (0.228) (p=0.16)

Overall 0.381 0.410 1.87 0.133 0.781 0.085(0.461) (0.458) (p=0.07)

Panel B: Effort Choices

R Initial Subsequent t-test Proportion Proportion ProportionBudget Share Budget Share (p-value) Present-Biased Dynamically Consistent Future-Biased

(1) (2) (3) (4) (5) (6)

0.5 0.787 0.761 1.76 0.294 0.444 0.263(0.180) (0.219) (p=0.08)

0.75 0.717 0.690 1.70 0.356 0.363 0.281(0.206) (0.245) (p=0.09)

1 0.541 0.489 3.65 0.237 0.656 0.106(0.134) (0.183) (p<0.01)

1.25 0.324 0.250 4.12 0.388 0.444 0.169(0.239) (0.222) (p<0.01)

1.5 0.289 0.222 3.67 0.369 0.425 0.206(0.242) (0.226) (p<0.01)

Overall 0.532 0.482 3.86 0.329 0.466 0.205(0.286) (0.311) (p<0.01)

Notes: Panel A tabulates t 6= 0 and t = 0 budget shares for sooner payments for each P in money. Each row

calculates from 75 t 6= 0 allocations (one at each interest rate in the Week 4 vs. Week 7 prospective choices) and

150 t = 0 allocations (one at each interest rate in the Week 4 vs. Week 7 actual and Week 1 vs. Week 4) choices.

Paired t-tests with 149 degrees of freedom presented. Panel B tabulates initial and subsequent budget shares

for sooner tasks for each R in effort. Each row calculates from 160 initial allocations (one each for tetris and

greek at each task rate) and 160 subsequent allocations. Paired t-tests with 159 degrees of freedom presented.

Overall tests in both panels come from regression of budget share on allocation timing with standard errors

clustered on individual level. Test statistic is t-statistic testing the null hypothesis of no effect of allocation

timing, which controls for multiple comparisons.

at time t, and ct+k, received at time t+ k, is

U(ct, ct+k) = (ct + ω)α + β1t=0δk(ct+k + ω)α. (3)

19

The variable 1t=0 is an indicator for whether or not the sooner payment date, t, is the present.

The parameter β captures the degree of present bias, while the parameter δ captures long run

discounting. β = 1 nests the standard model of exponential discounting. The utility function

is assumed to be concave, α < 1, such that first order conditions provide meaningful optima.

Here, ω is a Stone-Geary background parameter that we take to be the $5 minimum payment

of the monetary experiment.21 Maximizing (3) subject to the intertemporal budget constraint

(2) yields an intertemporal Euler equation, which can be rearranged to obtain

log(ct + ω

ct+k + ω) =

log(β)

α− 1· (1t=0) +

log(δ)

α− 1· k + (

1

α− 1) · log(P ). (4)

Assuming an additive error, this functional form can be estimated at the aggregate or individ-

ual level.22 One important issue to consider in estimation is the potential presence of corner

solutions. We provide estimates from two-limit Tobit regressions designed to account for the

possibility that the tangency condition implied by (4) does not hold with equality (for discus-

sion, see Wooldridge, 2002; Andreoni and Sprenger, 2012a). Discounting and utility function

parameters can be recovered via non-linear combinations of regression coefficients with stan-

dard errors estimated via the delta method. Appendix A provides a detailed discussion of

identification and estimation of discounting parameters for both monetary and effort choices.

21Andreoni and Sprenger (2012a) provide detailed discussion of the use of such background parameters andprovide robustness tests with differing values of ω and differing assumptions for the functional form of utilityin CTB estimates. The findings suggest that though utility function curvature estimates may be sensitive todifferent background parameter assumptions, discounting parameters, particularly present bias, are virtuallyunaffected by such choices.

22An additive error yields the regression equation

log(ct + ω

ct+k + ω) =

log(β)

α− 1· (1t=0) +

log(δ)

α− 1· k + (

1

α− 1) · log(P ) + ε.

The stochastic error term, ε, is necessary to rationalize any discrepancies between our theoretical developmentand our experimental data. One simple foundation for such an error structure would be to assume that indi-viduals exhibit random perturbations to their log allocation ratios, log( ct+ω

ct+k+ω). A more complete formulation

might follow macroeconomic exercises such as Shapiro (1984), Zeldes (1989), and Lawrance (1991). With atime series of consumption, one assumes rational expectations such that Euler equations are satisfied up to amean zero random error, uncorrelated with any information available to the decisionmaker. Assuming constantrelative risk aversion, as we do, this forecast error provides the structure for estimating utility function curvatureand recovering discounting parameters in a way very similar to our exercise.

20

23

Table 3: Parameter Estimates

Monetary Discounting Effort Discounting

(1) (2) (3) (4) (5)All Delay Three Week Delay Job 1 Job 2 CombinedLengths Lengths Greek Tetris

Present Bias Parameter: β 0.974 0.988 0.900 0.877 0.888(0.009) (0.009) (0.037) (0.036) (0.033)

Weekly Discount Factor: (δ)7 0.988 0.980 0.993 1.007 0.999(0.003) (0.003) (0.027) (0.029) (0.025)

Monetary Curvature Parameter: α 0.975 0.976(0.006) (0.005)

Cost of Effort Parameter: γ 1.624 1.557 1.589(0.114) (0.099) (0.104)

# Observations 1500 1125 800 800 1600# Clusters 75 75 80 80 80Job Effects Yes

H0 : β = 1 χ2(1) = 8.77 χ2(1) = 1.96 χ2(1) = 7.36 χ2(1) = 11.43 χ2(1) = 11.42(p < 0.01) (p = 0.16) (p < 0.01) (p < 0.01) (p < 0.01)

H0 : β(Col. 1) = β(Col. 5) χ2(1) = 6.37(p = 0.01)

H0 : β(Col. 2) = β(Col. 5) χ2(1) = 8.27(p < 0.01)

Notes: Parameters identified from two-limit Tobit regressions of equations (4) and (6) for monetary discounting

and effort discounting, respectively. Parameters recovered via non-linear combinations of regression coefficients.

Standard errors clustered at individual level reported in parentheses, recovered via the delta method. Effort

regressions control for Job Effects (Task 1 vs. Task 2). Chi-squared tests inlast three rows.

In Table 3, columns (1) and (2) we implement two-limit Tobit regressions with standard

errors clustered at the individual level. In column (1) we use all 4 CTB choice sets. In column (2)

we use only the choice sets which have three-week delays for continuity with our non-parametric

evidence. Across specifications we identify weekly discount factors of around 0.99. The 95%

confidence interval in column (1) for the weekly discount factor implies annual discount rates

between 40% and 140%.24 In column (1) of Table 3 we estimate β = 0.974 (s.e. = 0.009),

23The notation of Appendix A is slightly altered to discuss allocation timing and make links to partialsophistication and the value of commitment for effort choices.

24In Appendix A, we discuss identification of all parameters and note that discount factors are identifiedfrom variation in delay length, k. Our ability to precisely identify aggregate discounting was not a focus of

21

economically close to, though statistically different from dynamic consistency, H0 : β = 1:

χ2(1) = 8.77, (p < 0.01). In column (2), focusing only on three week delays, we find β =

0.988 (0.009) and are unable to reject the null hypothesis of dynamic consistency, H0 : β = 1:

χ2(1) = 1.96, (p = 0.16). These estimates demonstrate limited present bias for money and

hence confirm the non-parametric results.

In both specifications, we estimate α of around 0.975 indicating limited utility function

curvature over monetary payments. Finding limited curvature over money is important in its

own right, as linear preferences over monetary payments are indicative of fungibility. There

is no desire to smooth monetary payments as there might be for consumption, with subjects

treating money received at different points in time effectively as perfect substitutes. Supporting

these estimates, note that 86% of monetary allocations are corner solutions and 61% of subjects

have zero interior allocations in twenty decisions.25

Our non-parametric and parametric results closely mirror the aggregate findings of Andreoni

and Sprenger (2012a) and Gine et al. (2010).26 A potential concern of these earlier studies that

carefully control transaction costs and payment reliability, is that a payment in the present

was implemented by a payment in the afternoon of the same day, e.g. by 5:00 pm in the

subjects’ residence mailboxes in Andreoni and Sprenger (2012a). In this paper, because subjects

repeatedly have to come to the lab, a payment in the present is implemented by an immediate

cash payment. The fact that we replicate the earlier studies that carefully control for transaction

costs and payment reliability alleviates the concerns that payments in the afternoon are not

treated as present payments.

To summarize, we confirm the finding of limited present bias in the domain of money. This

the experimental design and is compromised by limited variation in delay length. In monetary discountingexperiments it is not unusual to find implied annual discount rates in excess of 100%.

25A consequence of limited utility function curvature is that even a small degree of present bias can leadpotentially to sizable changes in allocation behavior through time as individuals may switch from one cornersolution to another. Hallmarks of this are seen in Table 2, which tabulates behavior across interest rates.Though a wide majority of observations are dynamically consistent, some significant changes in budget sharesare seen at specific interest rates.

26In both of these prior exercises substantial heterogeneity in behavior is uncovered. In subsection 3.3 weconduct individual analyses, revealing similar findings.

22

could be either because the good in question, money, is fungible, a hypothesis for which we

find some evidence (recall that we estimate α to be around 0.975). Alternatively, it could be

because present bias in the form provided by models of dynamic inconsistency does not exist

or exists in only very limited form. This motivates our exploration of choices over effort, which

we believe is closer to consumption than money is.

3.2 Effort Discounting

Subjects make a total of 40 allocation decisions over effort in our seven week experiment.

Twenty of these decisions are made in the first block of the experiment, and twenty in the second

block. One focus of our design is testing whether participants identified as being present-biased

in Block 1 demand commitment in Block 2. Hence, we opt to present here allocation data from

only the first block of the experiment. This allows the prediction of commitment demand to

be conducted truly as an out-of-sample exercise. In Appendix E.5 we present results of present

bias from both blocks of the experiment and document very similar findings.

In Figure 5, we show for each value of R from et + R · et+k = 50, the amount of tasks

allocated to the sooner work date, Week 2, which could range from 0 to 50.27 We contrast

initial allocations of effort made in Week 1 with subsequent allocations made in Week 2 for the

80 subjects of the primary sample. Standard error bars are clustered at the individual level.

As with monetary discounting, subjects appear to have understood the central intertemporal

tradeoffs of the experiment as both initial and subsequent allocations decrease as R is increased.

At the individual level, 95% of choices are monotonically decreasing in R, and only 5 subjects

exhibit more than 5 non-monotonicities in their effort choices.28 This suggests that subjects as

27The data are presented as a function of R from et +R · et+k = 50, as opposed to relative price, to providea standard downward sloping demand curve. Recall that R ∈ {0.5, 0.75, 1, 1.25, 1.5}. When R is low, soonertasks are relatively cheap to complete, and when R is high, sooner tasks are relatively expensive to complete.

28Subjects have 32 opportunities to violate monotonicity comparing two adjacent values of R in their 40 totalCTB choices. 41 of 80 subjects are fully consistent with monotonicity and only 5 subjects have more than 5non-monotonicities. Deviations are in general small with a median required allocation change of 3 tasks to bringthe data in line with monotonicity. Three subjects have more than 10 non-monotonicities indicating upwardsloping sooner effort curves. Such subjects may find the tasks enjoyable such that they prefer to do more taskssooner to fewer tasks later. We believe the increased volume of non-downward sloping behavior in effort relativeto money has several sources. Subjects may actually enjoy the tasks, they make more choices for effort than

23

Figure 5: Real Effort Discounting Behavior

1020

3040

.5 1 1.5 .5 1 1.5

Greek Transcription Tetris

Initial AllocationMean

Subsequent AllocationMean SE

Task

s Al

loca

ted

to E

arly

Dat

e

R(from et+Ret+k=50)

Graphs by task

a whole understand the implied intertemporal tradeoffs and the decision environment.

Apparent from the observed choices is that at all values of R average subsequent allocations

lie below average initial allocations. Controlling for all R and task interactions, subjects allocate

2.47 fewer tasks to the sooner work date when the sooner work date is the present F (1, 79) =

14.78, (p < 0.01). Subjects initially allocate 9.3% more tasks to the sooner work date than

they subsequently allocate (26.59 initial vs. 24.12 subsequent).29 Table 2, Panel B provides a

corresponding tabulation of behavior, presenting the budget share allocated to the sooner work

date and the proportion of choices that can be classified as present-biased. Budget shares for

the sooner work date are calculated as et/m for each allocation. Across all values of R, subjects

for money, and half of their allocations are completed outside of the controlled lab environment. Importantly,non-monotonicities decrease with experience such that in the second block of the experiment 97 percent ofchoices satisfy monotonicity while in the first block, only 93 percent do so, F (1, 79) = 8.34 (p < 0.01).

29The behavior is more pronounced for the first block of the experiment. For both blocks combined sub-jects allocate 25.95 tasks to the sooner date, 1.59 more tasks than they subsequently allocate (24.38 tasks),representing a difference of around 6%, F (1, 79) = 15.16, (p < 0.01). See Appendix E.5 for detail.

24

initially allocate around 53% (s.e. = 0.97) of their experimental budget to the sooner work date

and subsequently allocate around 48% (1.02) to the sooner work date, when that sooner work

date is in the present, F (1, 79) = 14.87, (p < 0.01). Across all values of R, forty-seven percent

of choices are dynamically consistent, 33% are present-biased, and 21% are future-biased.30

Motivated by our non-parametric analysis we proceed to estimate intertemporal parameters.

Subjects allocate effort to an earlier date, et, and a later date, et+k. We again assume quasi-

hyperbolic discounting and a stationary power cost function with Stone-Geary background

parameters to write the discounted costs of effort as

(et + ω)γ + β1t=0δk(et+k + ω)γ. (5)

Here γ > 1 represents the stationary parameter on the convex instantaneous cost of effort

function. The Stone-Geary term, ω, could be interpreted as some background level of required

work. For simplicity, we interpret ω as the required minimum work of the experiment and set

ω = 10 for our effort analysis. The variable 1t=0 is an indicator for whether or not the sooner

work date, t, is the present. As before, the parameter β captures the degree of present bias and

the parameter δ captures long run discounting.

Maximizing (5) subject to (1) (et,t +R · et+k,t = 50) yields an intertemporal Euler equation,

which can be rearranged to obtain

log(et + ω

et+k + ω) =

log(β)

γ − 1· (1t=0) +

log(δ)

γ − 1· k − (

1

γ − 1) · log(R). (6)

As before, we assume an additive error structure and estimate the linear regression implied

by (6) using two-limit Tobit regression. The parameters of interest are again recovered from

non-linear combinations of regression coefficients with standard errors calculated via the delta

method. Appendix A provides detailed discussion of identification for such choices.31

30Appendix Table A3 provides identical analysis using both blocks of data and reports very similar results.31The notation of Appendix A is slightly altered to discuss allocation timing and make links to partial

sophistication and the value of commitment for effort choices.

25

Table 3 columns (3) through (5) present two-limit Tobit regressions with standard errors

clustered on the individual level. In column (3) the analyzed data are the allocations for Job 1,

Greek Transcription. We find an estimated cost parameter γ = 1.624 (0.114). Abstracting from

discounting, a subject with this parameter would be indifferent between completing all 50 tasks

on one work date and completing 32 tasks on both work dates.32 This suggests non-fungibility in

the allocation of tasks as individuals do desire to smooth intertemporally. A further indication

of non-fungibility is that in contrast to the monetary choices, only 31% of allocations are at

budget corners and only 1 subject has zero interior allocations. The weekly discount factor of

δ = 0.993 is similar to our findings for monetary discounting.

In column (3) of Table 3 we estimate an aggregate β = 0.900 (0.037), and reject the null

hypothesis of dynamic consistency, χ2(1) = 7.36, (p < 0.01). In column (4), we obtain broadly

similar conclusions for Job 2, the modified Tetris games. We aggregate over the two jobs in

column (5), controlling for the job, and again document that subjects are significantly present-

biased over effort.33 The results of column (5) indicate that discount rates measured in advance

of the Week 2 work date are around zero percent per week while discount rates measured on the

Week 2 work date are around eleven percent per week. We therefore confirm our non-parametric

findings on effort choices.

Finally, our implemented analysis allows us to compare present bias across effort and money

with χ2 tests based on seemingly unrelated estimation techniques. We reject the null hypothesis

that the β identified in column (5) over effort is equal to that identified for monetary discounting

in column (1), χ2(1) = 6.37, (p = 0.01), or column (2), χ2(1) = 8.27, (p < 0.01). Subjects are

significantly more present-biased over effort than over money.34

32In many applications in economics and experiments, quadratic cost functions are assumed for tractabilityand our analysis suggests that at least in our domain this assumption would not be too inaccurate.

33For robustness, we run regressions similar to column (5) separately for each week and note that though thecost function does change somewhat from week to week, present bias is still significantly identified as individualsare significantly less patient in their subsequent allocation decisions compared to their initial allocation decisions.Appendix Table A10 provides estimates.

34In Appendix E.5 we conduct identical analysis using both Blocks 1 and 2 and arrive at the same conclusions.See Appendix Table A11 for estimates.

26

3.3 Individual Analysis

On aggregate, we find that subjects are significantly more present-biased over work than over

money. In this sub-section we investigate behavior at the individual level to understand the

extent to which present bias over effort and money is correlated within individual.

In order to investigate individual level discounting parameters we run fixed effect versions

of the regressions provided in columns (2) and (5) of Table 3.35 These regressions assume no

heterogeneity in cost or utility function curvature and recover individual parameter estimates

of βe, present bias for effort, and βm, present bias for money, as non-linear combinations

of regression coefficients. The methods for identifying individual discounting parameters are

discussed in Appendix A.36 Appendix Tables A5 and A6 provide individual estimates of βe and

βm along with a summary of allocation behavior for both effort and money for each subject.37

Figure 6 presents individual estimates and their correlation. First, note that nearly 60%

of subjects have an estimated βm close to 1, indicating dynamic consistency for monetary

discounting choices. This is in contrast to only around 25% of subjects with βe close to 1. The

mean value for βm is 0.99 (s.d. = 0.06), while the mean value for βe is 0.91 (s.d. = 0.20). The

difference between these measures is significant, t = 3.09, (p < 0.01). Second, note that for the

majority of subjects when they deviate from dynamic consistency in effort, they deviate in the

direction of present bias.

Since correlational studies (e.g., Ashraf et al., 2006; Meier and Sprenger, 2010) often use

35We choose to use the measures of present bias based on three week delay choices for the monetary discountingfor continuity with our non-parametric tests of present bias. Further, when validating our individual measures,we focus on allocations over three week delay decisions as in the presentation for the aggregate data. Verysimilar results are obtained if we use the fixed effects versions of Table 3, column (1).

36One technical constraint prevents us from estimating individual discounting parameters with two-limit Tobitas in the aggregate analysis. In order for parameters to be estimable at the individual level with two-limit Tobit,some interior allocations are required. As noted above, 86% of monetary allocations are at budget corners and61% of the sample has zero interior allocations. For effort discounting, 31% of allocations are at budget cornersand 1 subject has zero interior allocations. To estimate individual-level discounting, we therefore use ordinaryleast squares for both money and effort. Nearly identical aggregate discounting estimates are generated whenconducting ordinary least squares versions of Table 3. Curvature estimates, however, are sensitive to estimationtechniques that do and do not recognize that the tangency conditions implied by (6) and (4) may be met withinequality at budget corners. Se Andreoni and Sprenger (2012a) for further discussion.

37Appendix Tables A5 and A6 include data from the 9 subjects excluded from the primary study sample forhaving no variation in experimental response in one or more weeks of the study. These subjects are noted alongwith an explanation of which weeks they provided no variation in response.

27

binary measures of present bias, we define the variables ‘Present-Biased’e and ‘Present-Biased’m

which take the value 1 if the corresponding estimate of β lies strictly below 0.99 and zero

otherwise. We find that 56% of subjects have a ‘Present-Biased’e of 1 while only 33% of

subjects have a ‘Present-Biased’m of 1. The difference in proportions of individuals classified

as present-biased over work and money is significant, z = 2.31, (p = 0.02).38

Figure 6: Individual Estimates of Present Bias

0.2

.4.6

Frac

tion

.5 .75 1 1.25 1.5Work Present Bias

0.2

.4.6

Frac

tion

.5 .75 1 1.25 1.5Monetary Present Bias

.8.9

11.

11.2

Mon

etar

y Pr

esen

t Bia

s


Two important questions with respect to our individual measures arise. First, how much

do these measures correlate within individual? The answer to this question is important for

understanding both the validity of studies relying on monetary measures and the potential

consistency of preferences across domains. Significant correlations would suggest that there may

be some important preference-related behavior uncovered in monetary discounting studies.39

38Further, one can define future bias in a similar way. 17% of subjects are future biased in money while 29%of subjects are future biased over effort. Similar differing proportions between present and future bias havebeen previously documented (see, e.g., Ashraf et al., 2006; Meier and Sprenger, 2010). Two important counter-examples are Gine et al. (2010) who find almost equal proportions of present and future biased choices andDohmen, Falk, Huffman and Sunde (2006) who find a greater proportion of future-biased than present-biasedsubjects.

39Indeed psychology provides some grounds for such views as money generates broadly similar rewards-relatedneural patterns as more primary incentives (Knutson, Adams, Fong and Hommer, 2001), and in the domainof discounting evidence suggests that discounting over primary rewards, such as juice, produces similar neuralimages to discounting over monetary rewards (McClure, Laibson, Loewenstein and Cohen, 2004; McClure et

28

Figure 6 presents a scatterplot of βm and βe. In our sample of 75 subjects with both complete

monetary and effort discounting choices, we find that βe and βm have almost zero correlation,

ρ = −0.05, (p = 0.66). Additionally, we find that the binary measures for present bias,

‘Present-Biased’e and ‘Present-Biased’m are also uncorrelated, ρ = 0.11, (p = 0.33).40

The second question concerning our estimated parameters is whether they can be validated

in sample. That is, given that βe and βm are recovered as non-linear combinations of regression

coefficients, to what extent do these measures predict present-biased allocations of tasks and

money? In order to examine this internal validity question, we generate difference measures for

allocations. For effort choices we calculate the budget share of each allocation for Week 2 effort.

The difference in budget shares between subsequent allocation and initial allocation is what we

term a ‘budget share difference.’41 As budget shares are valued between [0, 1], our difference

measure takes values on the interval [−1, 1]. Negative numbers indicate present-biased behavior

and values of zero indicate dynamic consistency. Each subject has 10 such effort budget share

difference measures in Block 1. The average budget share difference for effort is -0.049 (s.d.

= 0.115) indicating that subjects allocate around 5% less of their work budget to the sooner

work date when allocating in the present.42 At the individual level, 49 of 80 subjects have an

average budget share difference of less than zero, 13 have an average difference of exactly zero,

and 18 have an average difference greater than zero, demonstrating a modal pattern of present

bias.

A similar measure is constructed for monetary discounting choices. Taking only the three

week delay data, at each value of P we take the difference between the future allocation (Week 4

vs. Week 7 (Prospective)) budget share and the present allocation (Week 1 vs. Week 4 or Week

al., 2007).40Interestingly, when using both Blocks 1 and 2 of the data, we come to a slightly different conclusion. Though

βm and βe remain virtually uncorrelated, with the additional data we uncover a substantial and significantcorrelation between Present-Biased’e and ‘Present-Biased’m ρ = 0.24, (p = 0.03). Further, ‘Present-Biased’mis also significantly correlated with the continuous measure βe, ρ = −0.27, (p = 0.02). More work is needed tounderstand the relationship between monetary and effort present bias parameters.

41Specifically, given an initial Week 1 allocation of e2 of work to be done in Week 2 and a subsequent allocation

of e′2 in Week 2 of work to be done in week 2, the budget share difference ise′2−e250 .

42As noted previously, this average value deviates significantly from the dynamically consistent benchmarkof 0, F (1, 79) = 14.87, (p < 0.01).

29

4 vs. Week 7) budget share. This measure takes values on the interval [−1, 1], with negative

numbers indicating present-biased behavior. Each subject has 10 such monetary budget share

difference measures. The average budget share difference for money is -0.029 (s.d. = 0.134).43

At the individual level, 28 of 75 subjects have an average budget share difference of less than

zero, 32 have an average difference of exactly zero, and 15 have an average difference greater

than zero, demonstrating a modal pattern of dynamic consistency.

The non-parametric budget share difference measures are closely correlated with our para-

metric estimates at the individual level. The correlation between βe and each individual’s

average budget share difference for effort is ρ = 0.948, (p < 0.01). Of the 49 individuals with

negative average budget share differences for effort, 47 have estimates of βe < 1. Of the 18 indi-

viduals with positive average budget share differences for effort, all 18 have estimates of βe > 1.

Of the 13 individuals with zero average budget share differences for effort, 11 have βe = 1 and

2 have βe = 1.003 . The correlation between βm and each individual’s average Budget Share

Difference for money is ρ = 0.997, (p < 0.01). Of the 28 individuals with negative average

budget share differences for money, all 28 have estimates of βm < 1. Of the 15 individuals with

positive average budget share differences for money, all 15 have estimates of βm > 1. Of the 32

individuals with zero average budget share differences for money, all 32 have βm = 1.44 This

apparent internal validity gives us confidence that our parameter estimates for present bias are

indeed tightly linked with present-biased data patterns, appropriately capturing the behavior.

In the next section we move out-of-sample to investigate commitment demand. The inves-

tigation of commitment demand is critical to ruling out potential alternative explanations for

time inconsistency in effort allocations. Our preferred explanation is the existence of a present

bias in individual decision-making. However, many alternative explanations exist for rational-

izing these data patterns. Chief among these alternatives are the existence of unanticipated

shocks to the cost of performing tasks (either in general or specific to tasks in Week 2), resolv-

43 As noted previously, this average value differs marginally significantly from the dynamically consistentbenchmark of 0, F (1, 74) = 3.50, (p = 0.07).

44Appendix Tables A5 and A6 provide all the corresponding estimates and average budget share data.

30

ing uncertainty between allocation times, and subject exhaustion or error. These alternative

explanations are considered in detail in Appendix C. Importantly, we show in Appendix C that

under none of these alternatives would we expect a clear link between the behavioral pattern of

reallocating fewer tasks to the present and commitment demand. This is in contrast to a model

of present bias under the assumption of sophistication. Sophisticated present-biased individuals

may have demand for commitment. In the next section we document commitment demand on

the aggregate level and link commitment to measured present bias.

3.4 Commitment

In Week 4 of our experiment, subjects are offered a probabilistic commitment device. Subjects

are asked whether they prefer the allocation-that-counts to come from their Week 4 allocations

with probability 0.1 (plus an amount $X) or with probability 0.9 (plus an amount $Y), with

either $X=0 or $Y=0. The second of these choices represents commitment and $X - $Y is

the price of commitment.45 We begin by analyzing the simple choice between commitment

and flexibility at price zero ($X=0 and $Y=0) and in subsection 3.4.1 we explore the value

of commitment and choices when X or Y are not zero. In the simple choice where neither

commitment nor flexibility were costly, 59% (47/80) of subjects choose to commit. We define

the binary variable ‘Commit (=1)’ which takes the value 1 if a subject chooses to commit in

this decision.

Figure 7 presents Block 1 task allocation behavior separated by commitment choice in

Block 2. Immediately apparent from Figure 7 is that experimental behavior separates along

commitment choice. Subjects who choose commitment in Week 4 made substantially present-

biased task allocations in Week 2 given their initial Week 1 allocations. Controlling for all task

rate and task interactions, subjects who choose commitment allocate 3.58 fewer tasks to the

sooner work date when it is the present, F (1, 46) = 12.18, (p < 0.01). Subjects who do not

45To avoid cutting the sample further, here we consider all 80 subjects in the primary sample. 4 of 80 subjectsswitched multiple times in the commitment device price list elicitation. Identical results are obtained excludingsuch individuals.

31

Figure 7: Commitment Choice and Allocation Behavior

Panel A: Commit (=0)

1020

3040

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Panel B: Commit (=1)

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Graphs by task

demand commitment make more similar initial allocations and subsequent allocations of effort.

Controlling for all task rate and task interactions, they only allocate 0.89 fewer tasks to the

sooner work date when it is the present, F (1, 32) = 4.01, (p = 0.05). Furthermore, subjects

who demand commitment in Week 4 altered their allocations by significantly more tasks than

32

subjects who did not demand commitment, F (1, 79) = 5.84, (p = 0.02).46

Table 4 generates a similar conclusion with parametric estimates. In columns (3) and (4), we

find that subjects who choose commitment in Block 2 are significantly present-biased over effort

in Block 1, χ2(1) = 9.00, (p < 0.01). For subjects who do not choose commitment, we cannot

reject the null hypothesis of β = 1 at conventional levels, χ2(1) = 2.64, (p = 0.10). Further,

we reject the null hypothesis of equal present bias across committers and non-committers,

χ2(1) = 4.85, (p = 0.03).47

In columns (1) and (2) of Table 4 we repeat this exercise, predicting commitment choice

for effort using present bias parameters from monetary decisions. While subjects who demand

commitment also seem directionally more present-biased for monetary decisions than subjects

who do not demand commitment, the difference is not significant, (p = 0.26).

These findings indicate that present bias in effort is significantly related to future commit-

ment choice. Individuals who are present-biased over effort are substantially more likely to

choose commitment at price zero. An important caveat for this exercise is that correlation

is far from perfect. For example, the raw correlation between βe and commitment choice is

ρ = 0.225, (p = 0.04), implying an R-squared value of around 5%. Substantial variance in the

choice of commitment remains unexplained. There are several potential reasons for this lack of

46When including the 9 subjects with insufficient variation, this relationship between commitment and present-biased reallocations is no longer significant. Committers reallocate 0.90 (clustered s.e. = 1.32) fewer tasks to thesooner work date when the sooner work date is the present compared to non-committers, F (1, 88) = 0.46, (p =0.49). We believe this is due to the fact that the nine subjects with insufficient variation lie at the extremes ofchanges in allocations in Block 1. Two of the nine would lie below the 5th percentile in budget share differences(leading to βe estimates of 0.24 and 0.25) and one would lie above the 95th percentile (leading to a βe estimateof 2.63). Removing these three extreme subjects, we find that committing subjects reallocate 2.19 (1.12) fewertasks to the sooner work date when it is the present compared to non-committers, F (1, 88) = 3.86, (p = 0.05).

47These results are stronger for the first block of the experiment prior to the offering of the commitmentdevice, though the general patterns holds when we use both blocks of data. Appendix Table A12 providesanalysis including the data from both blocks. It is worth noting that the estimates of weekly discount factors, δalso differ across committing and non-committing subjects. This difference is identified from differences in initialallocations. Non-committing subjects have an average initial budget share for sooner tasks of 50.7% (clustereds.e. = 1.6) and an average subsequent budget share of 49.0% (1.7), while committing subjects have an averageinitial budget share of 54.9% (1.3) and an average subsequent share of 47.7% (1.4). Committing subjects’behavior is consistent with δ > 1. However, we hesitate to draw any firm conclusions from this observationas our experiment provides no variation in delay lengths to help identify δ. As discussed in Appendix A, δ isidentified from the constant one week delay between work dates. Hence, any level differences across subjectsare revealed as differences in estimated δ parameters.

33

Table 4: Monetary and Real Effort Discounting by Commitment


Commit (=0) Commit (=1) Commit (=0) Commit (=1)

(1) (2) (3) (4)Tobit Tobit Tobit Tobit

Present Bias Parameter: β 0.999 0.981 0.965 0.835(0.010) (0.013) (0.022) (0.055)

Weekly Discount Factor: (δ)7 0.978 0.981 0.917 1.065(0.003) (0.005) (0.032) (0.039)


Cost of Effort Parameter: γ 1.553 1.616(0.165) (0.134)

# Observations 420 705 660 940# Clusters 28 47 33 47Job Effects - - Yes Yes

H0 : β = 1 χ2(1) = 0.01 χ2(1) = 2.15 χ2(1) = 2.64 χ2(1) = 9.00(p = 0.94) (p = 0.14) (p = 0.10) (p < 0.01)

H0 : β(Col. 1) = β(Col. 2) χ2(1) = 1.29(p = 0.26)

H0 : β(Col. 3) = β(Col. 4) χ2(1) = 4.85(p = 0.03)


and real effort discounting. Parameters recovered via non-linear combinations of regression coefficients. Stan-

dard errors clustered at individual level reported in parentheses, recovered via the delta method. Commit (=1)

or Commit (=0) separates individuals into those who did (1) or those who did not (0) choose to commit at a

commitment price of zero dollars. Effort regressions control for Job Effects (Job 1 vs. Job 2). Tested null hy-

potheses are zero present bias, H0 : β = 1, and equality of present bias across commitment and no commitment,

H0 : β(Col. 1) = β(Col. 2) and H0 : β(Col. 3) = β(Col. 4).

explanatory power. A natural first possibility is substantial naivete. Though our results suggest

at least partial sophistication, on average, many subjects may be naive with respect to their dy-

namic inconsistency. Further, among partially sophisticated individuals, there may be limited

correlation between behavior and beliefs such that individuals with both high and low values

of βe may share similar beliefs as to their future behavior. Third, there may be uncertainty

in the work environment uncontrolled by the researcher. Even sophisticated present-biased

34

individuals may wish to remain flexible. In subsection 3.4.1 and Appendix D we discuss un-

certainty and the benefits of flexibility in detail, noting that the value of commitment is likely

influenced by the unmodeled benefits of flexibility. Fourth, the allocation decisions may be

subject to substantial noise, leading at least partially to a misestimation of preferences and a

misclassification of subjects. Each of these forces may be at play to certain degree, reducing our

ability to tightly measure present bias and the extent of sophistication. However, our finding

of a significant present bias and a correlation between present bias and commitment demand

points to at least partial sophistication for some subjects.

It is comforting for a theory of sophisticated present bias to find that present bias predicts

commitment demand. However, the result is only meaningful if we can show that commitment

places a binding constraint on subjects’ behavior. Do individuals who demand commitment

actually restrict their own activities, forcing themselves to complete more work than they

instantaneously desire?48 Given the nature of our commitment device, commitment will bind

whenever initial allocations differ from subsequent allocations. Two such comparisons are

considered. First, we consider the first block of the experiment when no commitment contract

is available. How many more tasks would subjects have been required to complete in Week 2

had commitment been in place? To answer this question we examine budget share differences

for Block 1. Non-committers have a mean budget share difference of −0.018 (clustered s.e. =

0.009) allocating about 2 percentage points less of each budget to Week 2 when deciding in

the present. In contrast, committers have a mean budget share difference of −0.072 (0.020),

allocating 7 percentage points less to Week 2 when deciding in the present. While both values

are significantly different from zero (F (1, 79) = 4.14, (p = 0.05), F (1, 79) = 12.39, (p <

0.01), respectively), the difference between the two is also statistically significant, F (1, 79) =

5.88, (p = 0.02). Hence, had commitment been in place in Week 2 and had subjects made the

48Though our offered commitment contract allows individuals only to meaningfully restrict themselves, thisneed not be the case. One example would be to have individuals commit to completing at least 1 task at thesooner work date. As virtually all initial allocations and subsequent allocations satisfy this condition anyways,such commitment would not be meaningful and as such, should not serve as evidence for the theoreticallypredicted link between sophisticated present bias and commitment demand.

35

same choices, committers would have been required to complete significantly more work than

they instantaneously desired and would have been more restricted than non-committers. The

same analysis can be done for Block 2 focusing on required work in Week 5. Non-committers

have a mean budget share difference of 0.011 (0.017) while committers have a mean difference

of −0.030 (0.013). The difference for committers remains significantly different from zero,

F (1, 79) = 5.57, (p = 0.02), and the difference between the two remains significant at the

10% level F (1, 79) = 3.68, (p = 0.06).49 Hence, in the presence of commitment in Week 5,

committed subjects are required to complete significantly more work than they instantaneously

desire and are more restricted than non-committed subjects.

We are aware of two prior exercises exploring the potential extent of present bias and its

correlation with commitment demand. Kaur et al. (2010) link the apparently present-biased

behavior of working harder on paydays with demand for a dominated wage contract wherein

individuals choose a work target. If the work target is not met, an individual receives a low piece-

rate wage, while if it is met or exceeded the individual receives a higher piece rate wage. As the

dominated wage contract can be viewed as a commitment to complete a certain amount of work,

this represents a potential link between commitment and present bias. Commitment levels are

chosen by individuals themselves and are set to around one-sixth of daily production on average.

Calculations indicate that committing subjects would have missed their target with probability

around 0.091 in the absence of commitment, and do miss their target with commitment in

place with probability 0.026. Hence, commitment can viewed as binding in about 7.5 percent

of cases, effectively forcing an individual to do more work than they instantaneously desire.

Ashraf et al. (2006) consider hypothetical intertemporal choices over money, rice and ice cream

and link those to take-up of a savings commitment device. The authors show that present bias

in the hypothetical monetary decisions is significantly correlated at the 10% level with take-up

for women.

We contrast two dimensions of our study with these prior findings. The first concerns the

49The difference for non-committers is no longer significantly different from zero F (1, 79) = 0.39, (p = 0.53).

36

techniques used to measure dynamic inconsistency, and the second is the extent to which sub-

jects are bound by commitment. As opposed to monetary discounting measures or dynamic

inconsistency inferred from payday effects, we attempt to measure discounting directly with

intertemporal allocations of effort delivering identification. As opposed to commitments with

somewhat limited binding probabilities, our committing subjects are clearly bound by commit-

ment.

3.4.1 The Value of Commitment

A natural question is how much should subjects be willing to pay for commitment. In Appendix

A we present the value of commitment, V , as the utility difference between the discounted

costs of commitment and flexibility. Given our experimental structure we can only assess

the monetary value of commitment. Virtually nobody is willing to pay more than $0.25 for

commitment, with 91 percent of subjects preferring flexibility when the price of commitment

is $0.25. Likewise, nobody is willing to pay more than $0.25 for flexibility, with 90 percent of

subjects preferring commitment when the price of commitment is -$0.25. Taking the midpoint

of each person’s price list switching interval, the data thus imply a median valuation of $0.125.50

For committers and non-committers, the median valuation is $0.125 and $-0.125, respectively.

What do these monetary valuations imply for the extent of V and correspondingly for the

extent of sophistication? In Appendix A, we theoretically investigate the valuation of commit-

ment through the lens of the partially sophisticated quasi-hyperbolic model of O’Donoghue and

Rabin (2001). We recover the valuation of commitment, V , for stationary cost functions. This

analysis shows that the value of commitment is linked to the extent of sophistication, which

is governed by sophistication parameter β, reflecting an individual’s assessment of their future

present bias. If β = 1, an individual is perfectly naive, and if β = β, an individual is perfectly

sophisticated. Values of β ∈ {β, 1} correspond to partial sophistication. That present bias

is predictive of commitment demand at price zero indicates at least partial sophistication on

50For this measure we exclude the four individuals with multiple switching.

37

average, β < 1.

The level of V can be calculated directly for the fully sophisticated benchmark of β = β,

which implies a perfect forecast for present-biased behavior. Using the parameters estimates of

Table 4, columns (3) and (4) and the actual allocations at R = 1, we can calculate the fully-

sophisticated value of commitment for committing and non-comitting subjects. For comitting

subjects, we calculate VC=1 = 1.23, which can be expressed in equivalent number of tasks as

c−1(1.23) = 1.14 tasks. For non-comitting subjects, we calculate VC=0 = −2.06, which can be

expressed in equivalent number of tasks as -1.59 tasks.

To relate the value of roughly two tasks to mooney, note that on average, using minimum

work completion rate, subjects complete approximately 60 tasks per hour. Assuming earnings

of around $12 per hour and a constant task value, a subject would be willing to complete 1

task for around $0.20.51 Hence the monetary value of commitment should be around $0.23 for

committing subjects and the value of flexibility should be around $0.32 for non-committing

subjects. These values compare favorably to the monetary valuations reported above. Hence,

assuming complete sophistication and no additional benefits to flexibility, we predict monetary

commitment valuations reasonably close to the valuations expressed by subjects.52

We are hesitant to draw strong conclusions beyond the plausibility of sophistication from

our commitment valuation data. First, given the ex-post parameter estimates, our elicitation

procedure clearly was not optimized for fine price differentiations. Second, it is possible that

subjects largely followed the money in the elicitation, preferring either commitment or flexi-

bility depending on which option provided additional payment. A direct experiment precisely

identifying β is a clear next step that research in this vein should take.

51The assumption of constant per task reservation value is important. With convex costs an individual shouldhave a lower reservation value for the first task than the sixtieth. We opt to present the average valuationrecognizing the possibility that valuations could be either higher or lower. Appendix D analyzes the value ofcommitment demand at a wide range of potential per task valuations to provide sensitivity analysis.

52 If individuals are fully sophisticated, monetary valuations for commitment should be close to those observed.Naturally, evaluating β > β lowers the value of commitment and for β = 1 commitment should be worth exactlyzero. In Appendix D we analyze specific values of β and corresponding valuations for commitment under variousassumptions for the transformation of V to dollars. This analysis also considers all allocations, not only thoseat one interest rate. Clear from this exercise is that under the assumption of no additional benefits to flexibility,only in extreme cases should commitment be worth more than a dollar.

38

3.5 Between Subjects Replication Exercise

A key contribution of our data is the documentation of limited present bias in the domain of

money and more substantial present bias in the domain of work. One interpretation is that

models of dynamic inconsistency are validated when tested in their relevant domain (consump-

tion) and that choices over fungible monetary payments cannot easily speak to such models’

predictions.

However, in our within-subjects study, several design choices were made that might muddy

this interpretation. First, subjects faced different interest rates and forms of budget constraint

for effort and for money.53 Second, the delay lengths for money were three to six weeks, while

the delay lengths for effort were only one week. Third, subjects always completed their effort

allocations prior to completing their monetary allocations. Fourth, present bias is identified for

effort from only a dynamic choice, while present bias is identified for money from a combination

of static and dynamic choices.54 Fifth, for effort one allocation was chosen to be the allocation-

that-counts from the initial and subsequent allocations with an asymmetric probability, while

for money each allocation could be the alllocation-that-counts with equal probability. Further,

the Week 4 monetary choices were paid separately from the Week 1 choices. Though each

design choice has a natural motivation, including our desire to replicate prior exercises, one

could potentially imagine them influencing the degree of dynamic inconsistency.55

To alleviate these concerns, we conducted a between subjects replication exercise. 200

subjects, again from the UC Berkeley Xlab subject pool, were randomized into two conditions:

53That is, the constraint for effort was of a present value form, et + Ret+k = 50, while the constraint formoney was of a future value form, Pct + ct+k = 20.

54That is, for effort to identify present bias one compares the Week 1 allocations over Weeks 2 and 3 to theWeek 2 choices over Weeks 2 and 3. For money to identify present bias one compares the Week 1 allocationsover Weeks 4 and 7 to the Week 4 choices over Weeks 4 and 7, the Week 1 allocations over Weeks 1 and 4to the Week 1 allocations over Weeks 4 and 7, and the Week 1 allocations over Weeks 1 and 4 to the Week 1allocations over Weeks 1 and 7.

55The specific rationale for each choice, respectively: first, we expected substantially more curvature for effortthan money, which suggests different interest rates to avoid corner solutions. Second, we organized the monetarychoices around dates the subjects would come to the lab to equalize transactions costs. Third, our primary focuswas the effort choices, hence we sought to ensure theses data were collected. Fourth, we wished to replicate thestandard static evidence on present bias in money and benefited from an opportunity in Week 4 to additionallygenerate dynamic evidence. Fifth and sixth, we did not wish to burden the subjects with another, potentiallycomplicated, procedure for determining which monetary decision would be implemented.

39

one in which allocations were made for money and one in which allocations were made for greek

transcription. In both conditions subjects selected into a four week study on decision-making

over time and were informed that their earnings would be approximately $60 if all aspects of the

study were completed. The main goal of the replication exercise is to keep allocation decisions

identical, with the only difference being whether allocations are over money or effort.

Mirroring our effort study, in Week 1 of the replication exercise subjects make allocations

over Weeks 2 and 3. In Week 2, subjects again make allocations over Weeks 2 and 3. All

allocations are made on a study website either in the lab in Week 1 or on any computer with

internet access in Week 2. In Week 2, one of the Week 1 or Week 2 decisions is chosen at

random, with each having equal probability, and the corresponding allocation is implemented.

For both effort and money, allocations are made using budgets of the form,

Pa2 + a3 = m.

Where a2 refers to an allocation of either effort or money to Week 2 and a3 refers to

an allocation of either effort or money to Week 3. For both effort and money P ∈

{0.66, 0.8, 0.91, 0.95, 1, 1.05, 1.11, 1.25, 1.54}, covering the interest rates used for both money

and effort from our initial experiment. For money m = $20 and for effort m = 60 tasks,

such that units are easily matched by dividing by three. Following our prior study, minimum

payments of $5 and minimum work of 10 tasks are implemented in Weeks 1, 2, and 3.

We attempt to put precise time stamps on both the completion of tasks and the collection of

money. For effort, subjects are told they must complete their tasks from the chosen allocation

on a study website between 9 am and 6 pm on the relevant day in Weeks 2 and 3. For

money, subjects are told they must collect their payments from the chosen allocation at the

UC Berkeley Xlab between 9 am and 6 pm on the relevant day in Weeks 2 and 3. To make

the Week 2 allocations as immediate as possible, subjects are additionally told in advance they

will have to either complete their Week 2 tasks or collect their Week 2 funds within two hours

of making their Week 2 allocations. Appendix G has the full study instructions.

40

If subjects complete all aspects of the study, including collecting their money or completing

their tasks on each relevant date within the relevant time window, they are eligible for a

completion payment paid in the fourth week of the study. For effort, the completion payment

is $60 with a non-completion payment of $5. For money, the completion payment is $30 with a

non-completion payment of $5. All payments, including those from monetary allocations, are

made in cash at the Xlab by a single research assistant who remained in place from 9 am to 6

pm on the relevant dates. All 200 subjects began the study on Thursday April 17, 2014. Of

these a total of 194 completed the study on Thursday May 1, 2014, with 95 from the effort

condition and 99 from the money condition.

In this between subjects design, we can directly compare present bias across conditions.

Figure 8 plots the amount of money in Panel A (out of $20) or the number of tasks in Panel B

(out of 60) and allocated to Week 3 for each level of P . Separate series are provided for when

the allocation is made in Week 1 and in Week 2. Note that because the budget constraints are

identical, Week 3 tasks are decreasing in P , while Week 3 money is increasing in P . Note as well

that due to the form of the budget, it is the constant-value Week 3 units that are graphed.56

Figure 8 closely reproduces our prior within-subject findings. For money mean behavior

appears almost perfectly dynamically consistent. Controlling for P , subjects allocate $0.14

(clustered s.e. = 0.12) less to Week 3 in Week 2 relative to Week 1, F (1, 98) = 1.37, p = 0.25.

In contrast, at each value of P , individuals appear present-biased for effort, allocating more

effort to the later date when the sooner date is the present. Controlling for P , subjects allocate

2.14 (clustered s.e. = 1.10) more tasks to Week 3 in Week 2 relative to Week 1, F (1, 94) =

3.82, p = 0.05. Appendix Table A4 provides a corresponding tabulation of behavior, presenting

budget shares and the proportion of choices that can be classified as present-biased.57

56This is in contrast to the prior effort figures where earlier tasks had constant value and were graphed andthe prior money figures where earlier money was also graphed for ease of comparison.

57For consistency with Table 2 and Appendix Table A3, Appendix Table A4 tabulates budget shares for thesooner date, calculated as (Pa2)/m for each allocation. For money, subjects initially allocate around 51.4% (0.7)of their experimental budget to the sooner payment and subsequently allocate around 51.9% (0.6) to the soonerpayment, F (1, 98) = 0.85, (p = 0.36). Eighty-three percent of individual choices are dynamically consistent,10% are present-biased, and 7% are future-biased. For effort, subjects initially allocate around 52.4% (clustereds.e. = 1.1) of their experimental budget to the sooner work date and subsequently allocate around 48.8% (1.7)

41

Figure 8: Between Subjects Replication Exercise

05

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20D

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Panel B: Effort

Week 1 AllocationMean

Week 2 AllocationMean SE

Non-parametric replication in hand, we now turn to estimation of aggregate utility parame-

ters. In Table 5, we replicate the estimation exercise of Table 3 with the new between-subjects

data. The parameter values and corresponding conclusions are effectively unchanged. For

monetary present bias in column (1), we estimate β = 0.997 (clustered s.e. = 0.005), which

compares favorably to Table 3, column (2), which estimates β = 0.988 (0.009). Similar to

our within-subjects conclusion, we fail to reject the null hypothesis of dynamic consistency,

β = 1, for money, χ2(1) = 0.50, (p = 0.48). Interestingly, we also find quite similar discount

factor and curvature estimates between Table 5, column (1) and Table 3, column (2). For effort

present bias in column (2), we estimate β = 0.892 (0.056), which compares favorably to Table

3, column (3) for greek transcription where β = 0.900 (0.037). Similar to our within-subjects

conclusion, we reject the null hypothesis of β = 1 for effort, χ2(1) = 3.73, (p = 0.05). Again,

we find quite similar estimates for the auxiliary parameters between Table 5, column (2) and

to the sooner work date, F (1, 94) = 3.82, (p = 0.05). Twenty-five percent of individual choices are dynamicallyconsistent, 43% are present-biased, and 32% are future-biased.

42

Table 3, column (3). The analysis again allows us to compare present bias across effort and

money, and again we reject the null hypothesis that the β identified for money is equal to that

identified for effort, χ2(1) = 3.50, (p = 0.06).58

Though these findings closely replicate our prior within-subjects data, it is important to

note that the data from this exercise yields somewhat less precise measures and test statistics

than our initial study. We hesitate to speculate as to the source of this imprecision, and draw

some comfort from the replication of the point estimates from our prior work.

Table 5: Replication Exercise Parameter Estimates

Monetary Discounting Effort DiscountingGreek

(1) (2))

Present Bias Parameter: β 0.997 0.892(0.005) (0.056)

Weekly Discount Factor: (δ)7 0.998 1.009(0.001) (0.005)

Monetary Curvature Parameter: α 0.952(0.009)

Cost of Effort Parameter: γ 1.774(0.167)

# Observations 1782 1710# Clusters 99 95

H0 : β = 1 χ2(1) = 0.50 χ2(1) = 3.73(p = 0.48) (p = 0.05)

H0 : β(Col. 1) = β(Col. 2) χ2(1) = 3.50(p = 0.06)



Standard errors clustered at individual level reported in parentheses, recovered via the delta method. Chi-

squared tests used in last two rows.

58Appendix Tables A7 and A8 provide individual estimates of βe and βm along with a summary of allocationbehavior for these subjects. Subjects with no variation in experimental response in a given week are also noted.16 of 194 non-attriting subjects have no variation in experimental response in one or more weeks and 14 of thesesubjects were in the effort condition. Importantly, the results of Table 5 are maintained if we eliminate suchsubjects with no variation in one or more weeks. See Appendix Table A13 for detail.

43

4 Conclusion

Present biased time preferences are a core of behavioral research. The key hypothesis of dimin-

ishing impatience through time is able to capture a number of behavioral regularities at odds

with standard exponential discounting. Further, the possibility of sophistication provides an

important channel for policy improvements via the provision of commitment devices. With the

exception of only a few pieces of research, most evidence of dynamic inconsistency is generated

from experimental choices over time-dated monetary payments. When those are administered

in a way to keep transaction costs constant and uncertainty at bay, recent studies have found

limited evidence of dynamic inconsistency. However, such findings may not be appropriate to

reject a model defined over streams of consumption.

The present study attempts to identify dynamic inconsistency for choices over real effort.

We introduce a longitudinal design asking subjects to allocate and subsequently allocate again

units of effort through time. A complementary monetary study is conducted for comparison.

We document three key findings. First, in choices over monetary payments, we find limited evi-

dence of present bias, confirming earlier work. Second, in choices over effort, we find substantial

present bias. Subjects reallocate about 9% less work to the present than their initial allocation.

Corresponding parameter estimates generate a similar conclusion. Individuals are estimated to

be substantially present-biased in effort choices and significantly closer to dynamically consis-

tent in choices over money. Third, we study commitment demand, documenting that at price

zero roughly 60% of subjects prefer commitment to flexibility. A key result is that these com-

mitment decisions correlate significantly with previously measured present bias. Individuals

who demand commitment are significantly more present-biased in effort than those who do

not. This provides validation for our experimental measures and helps to rule out a variety of

potential confounds. Importantly, in our design commitment meaningfully restricts activities.

Committed subjects are required to complete more effort than they instantaneously desire.

By documenting the link between experimentally measured present bias and commitment de-

mand, we provide support for models of dynamic inconsistency with sophistication. Subjects

44

are potentially aware of their present bias and take actions to limit their future behavior.

We view our paper as providing a portable experimental method allowing tractable esti-

mation of intertemporal preferences over consumption (effort) and correlating such preferences

with a meaningful, potentially constraining, commitment device. Though the implementation

here is with American undergraduates, we feel the design is suitable for field interventions.

We draw one conclusion and several words of caution from our findings. Our results indicate

that present bias is plausibly identified in choices over effort and, furthermore, is linked to

effort-related commitment demand. However, we caution using the estimated parameters at

face value as they are for a specific subject pool (self-selected to work for six weeks for final

payment in week seven) and a specific task. There may be other decision environments wherein

behavior may not be well captured by models of dynamic inconsistency. For example, subjects

may wish to get a painful single experience over with immediately or postpone a single pleasure

(Loewenstein, 1987).59 Lastly and most importantly, though fungibility issues may be mediated

in the present design, the natural problems of arbitrage will still exist if subjects substitute

effort in the lab with their extra-lab behavior. The existence and use of such substitutes, like

avoiding doing laundry or homework in response to the experiment, will confound our measures

in much the same way as monetary studies. Discounting will be biased towards market interest

rates, present bias will be exhibited only if such rates change through time, and cost functions

will be biased towards linearity. Though our data suggest effort is less fungible than money,

one cannot say that extra-lab smoothing opportunities for effort are eliminated. Hence, one

should view our measures as lower bounds on the true extent of dynamic inconsistency and the

instantaneous cost of tasks. We want to, however, point out that to some extent such fungibility

will be present in many dimensions in which time inconsistency has been measured. Ultimately,

the best measure of time inconsistency will be one that predicts ecologically relevant decisions

across a broad set of environments. This suggests important avenues for future research.

59This suggests a key anticipatory component of intertemporal behavior, potentially mediated by our design’suse of minimum effort requirements and convex decisions.

45

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50

APPENDIX - NOT FOR PUBLICATION

A Theoretical Structure and Identification Appendix

In the intertemporal allocation of effort and money, discounting and additional parameters can

be identified at either the aggregate or individual level under various structural assumptions.

In the following three appendix subsections we describe our theoretical environment, explore

the demand for commitment, demonstrate which experimental variation provides identification

of specific parameters of interest, and lay out methodology for estimation. A fourth subsection

presents estimation details for monetary discounting.

A.1 Effort Discounting

A.1.1 Allocation Timing

In the working over time experiment, subjects allocate effort to an earlier date, et, and a later

date, et+k, subject to the intertemporal budget constraint described in (1). Subjects make

allocations at two points in time, one at time s < t, and one at time t. The allocation-that-

counts is randomly implemented from time s with probability p and from time t with probability

1− p.60 Let et,s be the allocation of effort to time t chosen at time s. Let es∗t,t be the allocation

of effort to time t forecasted to be chosen at time t from the perspective of time s. That is, es∗t,t

captures what an individual at time s believes they will optimally choose at time t.

A.1.2 Preferences

To develop our theory, we assume an instantaneous cost function, c(e), for effort, e, that is

time separable, stationary, and of an expected utility form with respect to the probability

that an allocation is implemented. To aid our development and foreshadow our empirical

60We abstract from the fact that subjects make multiple allocations. Given the assumed separability overtime and in probabilities, this abstraction is innocuous.

1

implementation we also make a functional form assumption for the shape of c(·). We assume

c(e) = (e+ ω)γ,

where γ > 1 represents the stationary parameter on the convex instantaneous cost of effort

function. The additive term ω in the cost function could be interpreted as a Stone-Geary

minimum or as some background level of required work. Such parameters are used in monetary

discounting studies (Andersen et al., 2008; Andreoni and Sprenger, 2012a), and are either taken

from some external data source on background consumption or estimated from experimental

choices. For simplicity, we interpret ω as the required minimum work of the experiment and

set ω = 10 for our effort analysis.61

We assume discounting follows the quasi-hyperbolic partially sophisticated form proposed

by O’Donoghue and Rabin (2001). For two periods, t and t + k, discounting, D(t, t + k), is

captured by

D(t, t+ k) =

βδk if k > 0

1 if k = 0.

The parameter β captures the degree of present bias while the parameter δ captures long run

discounting. β = 1 nests the standard model of exponential discounting. From period s < t,

the discounted costs of effort at times t and t+ k can be written as

βδt−s(et,s + ω)γ + βδt+k−s(et+k,s + ω)γ.

61Andreoni and Sprenger (2012a) provide estimates for ω based on non-linear least squares techniques andanalyze the extent to which different assumptions for ω influence remaining parameter estimates. Though utilitycurvature and discounting are sensitive to varying assumptions for ω, present bias, β, is largely unaffected.Andersen et al. (2008) also provide some sensitivity analysis.

2

Eliminating common terms, the decision problem at time s can be written as

minet,s.et+k,sp · [(et,s + ω)γ + δk(et+k,s + ω)γ] +

(1− p) · [(es∗t,t + ω)γ + δk(es∗t+k,t + ω)γ]

s.t. et,s +R · et+k,s = m,

which yields the intertemporal Euler equation satisfied by the optimal allocation, (e∗t,s, e∗t+k,s),

(e∗t,s + ω

e∗t+k,s + ω)γ−1 1

δk=

1

R.

Note that the forecasted allocation, (es∗t,t, es∗t+k,t), and the probability of implementation, p, do

not feature in the intertemporal Euler due to the assumed separability. Similarly, the decision

problem at time t can be written

minet,t.et+k,tp · [(e∗t,s + ω)γ + βδk(e∗t+k,s + ω)γ] +

(1− p) · [[(et,t + ω)γ + βδk(et+k,t + ω)γ]]

s.t. et,t +R · et+k,t = m,

with corresponding Euler equation satisfied by the optimal allocation, (e∗t,t, e∗t+k,t),

(e∗t,t + ω

e∗t+k,t + ω)γ−1 1

βδk=

1

R

The prior allocation, (e∗t,s, e∗t+k,s), and the probability of implementation do not feature in the

intertemporal Euler. Any differences in allocations between time s and time t are delivered by

the present bias term, β.62

62A recent discussion of non-expected utility behavior in intertemporal settings has demonstrated that ap-parently present-biased behavior can be delivered by deviations from expected utility (see, e.g., Halevy, 2008).Under discounted expected utility, allocations over two periods should depend on the ratio of probabilities withwhich the allocations are realized. In two important conditions Andreoni and Sprenger (2012b) demonstrate inthe monetary domain that if sooner and later payments are paid independently with probability 0.5, behaviordeviates from the common ratio counterpart of all payments being certain. Under expected utility and atempo-

3

Combining our Euler equations we have

(e∗t,D + ω

e∗t+k,D + ω)γ−1 1

β1D=tδk=

1

R(7)

where D ∈ {s, t} represents whether the allocation decision was made at time t or time s. Note

that for β < 1, an allocation made at time t at a given R will have a lower value of e∗t,D than

an allocation made at time s. A present-biased individual allocates less work to time t at time

t than they did at time s.

Naturally, the prediction that dynamically inconsistent behavior depends only on β relies

on the assumption of a stationary cost function. Changes in the cost function through time

could easily lead to differences in allocations between time s and t. Such changing costs could

be delivered by a variety of sources. For example, there could be permanent shocks to the cost

function, perhaps due to a misforecasting of task difficulty. There could also be temporary

shocks due to some random events that impose time constraints or leave subjects more tired

and exhausted than they normally are. In section C we address these concerns directly and

provide evidence that such possibilities are unlikely to drive observed behavior.

A.1.3 Partial Sophistication

We allow for the fact that individuals may be partially sophisticated with respect to their

own present bias. The nature of sophistication follows that of O’Donoghue and Rabin (2001),

where β captures the belief an individual has on his future present bias: β = β represents full

sophistication, β = 1 represents full naivete, and β ∈ (β, 1) represents partial sophistication.

ral applications of prospect theory, the deviations cannot be rationalized. An intuition for the effect is that theindependent payment probabilities give subjects the opportunity to hedge through time. Cheung (Forthcoming)and Miao and Zhong (2012) demonstrate the importance of this intuition, as they show in the Andreoni andSprenger (2012b) setup that when one makes the two 0.5 realization probabilities perfectly correlated behavioris closer to the expected utility benchmark. In our environment, the implementation probability applies equallyto both the sooner and later work date, creating perfect correlation through time. Hence, the effects of Andreoniand Sprenger (2012b) are unlikely to be present. Additionally, because the same implementation probabilityapplies to both work dates, any non-linear treatment of p or 1− p must be applied equally, and so drop out ofmarginal conditions in exactly the same way that undistorted probabilities do. Further potential concerns withrespect to the asymmetry of p and 1−p in the design are addressed in our replication exercise where initial andsubsequent allocations are implemented with equal probability. See section 3.5 for detail.

4

This means that allocations at time t, forecasted at time s < t are

(es∗t,t, es∗t+k,t) = argmin p · [(e∗t,s + ω)γ + βδk(e∗t+k,s + ω)γ] +

(1− p) · [(est,t + ω)γ + βδk(est+k,t + ω)γ]

s.t. est,t +R · est+k,t = m.

If β ∈ (β, 1] an individual’s forecasted allocation, (es∗t,t, es∗t+k,t) will not accord with their actual

subsequent allocation, (e∗t,t, e∗t+k,t).

Note the sophistication parameter, β is absent from the Euler formulations above. This is

by construction both in the theory and the experimental design. An individual at time s may

forecast a level of present bias at time t but is incapable of controlling behavior at that point in

time. More importantly, this forecasted present bias at time t does not influence his behavior

at time s. The only actions available to the time t self is to complete the time s allocation

with probability p, complete the time t allocation with probability 1 − p, or opt out of the

experiment, foregoing $90. Given the high penalty, an individual at time s can appropriately

forecast the third action will not be taken. The individual is aware that he cannot control the

second action. Hence, he optimizes according to his time s preference as above with β absent

from the formulation. The parameter β will be important for our analysis of commitment in

which an individual at time s may indeed control time t behavior.

A.2 Commitment

In the second block of the experiment subjects are offered a probabilistic commitment device.

The commitment device favors the initial allocations made at time s over the subsequent

allocations made at time t by changing the time s implementation probability from p to 1− p

(i.e. from 0.1 to 0.9).

Recall that intertemporal Euler equations and allocations are independent of implementa-

tion probabilities. Hence, the value of commitment can be arrived at by comparing discounted

5

costs. An individual prefers to commit if the discounted costs of the chosen allocation at time

s are smaller than the discounted costs of the forecasted allocation for time t at time s.63 The

value of commitment is given as

V = (1− 2p) · βδt−s · {[(es∗t,t + ω)γ + δkc(es∗t+k,t + ω)γ]− [(e∗t,s + ω)γ + δkc(e∗t+k,s + ω)γ]}.

Note that the value of commitment, V , depends upon both actual allocations and forecasted

allocations at time s. Hence, the value of commitment depends upon the degree of sophistica-

tion. Clearly, for naive individuals with β = 1, (es∗t,t, es∗t+k,t) = (e∗t,s, e

∗t+k,s). Actual and forecasted

allocations are identical and the value of commitment is zero.

For sophisticated individuals, β ∈ [β, 1), actual allocations and forecasted allocations at

time s differ. By the definition of the minimum from the perspective of period s, (es∗t,t, es∗t+k,t)

yields higher discounted costs than (e∗t,s, e∗t+k,s). This implies that the value of commitment

should be positive provided p < 0.5, as in the experiment. As β diverges from 1, the value of

commitment increases. Appendix D provides further detail and corresponding simulated values.

The extent of commitment demand, when combined with parametric measures for discounting

and costs, can be informative for the extent of sophistication.

Naturally, there may be intrinsic benefits to flexibility. These unmodeled benefits to flexi-

bility could have many sources including future uncertainty in costs or task difficulty.64

63The inequality between discounted costs

(1− p) · [βδt−s(e∗t,s + ω)γ + βδt+k−sc(e∗t+k,s + ω)γ ] + p · [βδt−s(es∗t,t + ω)γ + βδt+k−sc(es∗t+k,t + ω)γ ] <

p · [βδt−s(e∗t,s + ω)γ + βδt+k−sc(e∗t+k,s + ω)γ ] + (1− p) · [βδt−s(es∗t,t + ω)γ + βδt+k−sc(es∗t+k,t + ω)γ ],

reduces to the inequality,

(e∗t,s + ω)γ + δkc(e∗t+k,s + ω)γ < (es∗t,t + ω)γ + δkc(es∗t+k,t + ω)γ ,

provided p < 0.5 as in the experiment. Subtracting the discounted costs one arrives at the value of commitment,

V = {p · [βδt−s(e∗t,s + ω)γ + βδt+k−sc(e∗t+k,s + ω)γ ] + (1− p) · [βδt−s(es∗t,t + ω)γ + βδt+k−sc(es∗t+k,t + ω)γ ]} −

{(1− p) · [βδt−s(e∗t,s + ω)γ + βδt+k−sc(e∗t+k,s + ω)γ ] + p · [βδt−s(es∗t,t + ω)γ + βδt+k−sc(es∗t+k,t + ω)γ ]}.

64Note that in the presence of such factors even sophisticated present-biased subjects may have low or evennegative values for commitment. Hence, it is critical that our design elicits the demand for both flexibility and

6

The value of commitment, V , is measured in the same units as the discounted costs of

effort. A potential shortfall of our design is that our experiment does not measure V directly

but rather measures its translation into dollars. Hence, we provide potential bounds on V based

upon assumptions for the transformation of V to dollars.

A.3 Identification

From the intertemporal Euler equation, (7), identification of discounting and the cost function

is straightforward. Rearranging and taking logs yields

log(et,D + ω

et+k.D + ω) =

log(β)

γ − 1· (1D=t) +

log(δ)

γ − 1· k − (

1

γ − 1) · log(R), (8)

which is linear in the key experimental parameters of whether allocations are made at time

t, 1D=t, and the log transform, log(R). In our implementation, variation in log(R) delivers

identification of the cost function, γ; the allocation being made in Week 1 (D = s) rather than

Week 2 (D = t) delivers identification of present bias, β; and the delay length, k = 7 days,

gives identification of the discount factor, δ.65

In order to estimate discounting and cost function parameters from aggregate data, we

assume an additive error structure and estimate the linear regression implied by (8). To be

specific, the regression equation is, for k = 7,

log(et + ω

et+k + ω)i = η0k + η1 · (1D=t)i + η2 · log(R)i + εi,

and we recover the parameters of interest as β = exp(η1/ − η2) and γ = 1 + 1/ − η2. Note

that δ = exp(η0/− η2) is recovered from the constant as only one delay length was used in the

experimental design.

The parameters of interest can be recovered from non-linear combinations of regression

commitment to assess the possible presence of such factors.65Of course, with only one delay length of seven days considered in the experiment, we have limited confidence

that our estimate of δ can be extrapolated to arbitrary delay lengths.

7

coefficients with standard errors calculated via the delta method. One important issue to

consider in estimation is the potential presence of corner solutions. We provide estimates from

two-limit tobit regressions designed to account for the possibility that the tangency condition

implied by (8) does not hold with equality (Wooldridge, 2002).

Estimating (8) is easily extended to the study of individual parameters. To begin, (8) can

be estimated at the individual level.66 However, with limited numbers of individual choices

it is helpful to consider alternative, more structured approaches. In particular, we allow for

heterogeneous discounting across individuals, but assume all individuals have the same cost

function. Consider a vector of fixed effects (1j)i which take the value 1 if observation i was

contributed by individual j. This leads to the fixed effects formulation

log(et,D + ω

et+k,D + ω)i =

log(δ)

γ − 1· k +

(log(δj)− log(δ))

γ − 1· (1j)i · k +

log(β)

γ − 1· (1D=t)i

+(log(βj)− log(β))

γ − 1· (1D=t)i · (1j)i −

1

γ − 1· log(R)i,

where δ, β refer to sample means, and δj, βj refer to individual-specific discounting parameters.

With an additive error structure this is easily estimable.67 The individual fixed effect interacted

with the decision being made in the present provides identification of the individual-specific

βj. In Appendix B we conduct simulation exercises under various correlation structures for the

true parameters of interest and document that the implemented estimation methods perform

well both at the aggregate and individual level.

A.4 Monetary Discounting

Our methods for recovering monetary discounting parameters at both the aggregate and indi-

vidual level closely follow those for effort. Following most of the literature, we abstract from

standard arbitrage arguments for monetary discounting and assume laboratory administered

66Broadly similar conclusions are reached when estimating (8) at the individual level, however, parameterprecision is greatly reduced and substantial estimate instability is uncovered in some cases.

67We allow both β and δ to vary across individuals such that the implemented regression is a standardinteraction with both level and slope effects.

8

rates are the relevant ones.68 In particular, for monetary payments, ct and ct+k, allocated

subject to the constraint (2), we assume a quasi-hyperbolic constant relative risk averse utility

function,

U(ct,D, ct+k,D) = (ct + ω)α + β1D=tδk(ct+k + ω)α. (9)

Where D ∈ {s, t} refers to the same notation as before for when the allocation decision is made.

The utility function is assumed to be concave, α < 1, such that first order conditions provided

meaningful optima. Here, the parameter ω is a background parameter that we take to be the

$5 minimum payment of the monetary experiment.69

Maximizing (9) subject to the intertemporal budget constraint (2) yields an intertemporal

Euler equation similar to that above for effort. Taking logs and rearranging we have

log(ct,D + ω

ct+k,D + ω) =

log(β)

α− 1· (1D=t) +

log(δ)

α− 1· k + (

1

α− 1) · log(P ). (10)

Again, assuming an additive error structure, this can be estimated at the aggregate or individual

level via two-limit Tobit. Discounting and utility function parameters can be recovered via non-

linear combinations of regression coefficients as above with standard errors estimated again via

the delta method.

B Simulation Appendix

This appendix focuses on two questions related to the estimation strategies laid out in Ap-

pendix A. First, we examine the extent to which the implemented estimators identify the true

68The assumptions that individuals narrowly bracket time-dated experimental payments, treat money effec-tively as consumption, and ignore extra-lab arbitrage have been standard in the literature. One prominentexception to this tradition is Harrison et al. (2002), who measure and account for extra-lab borrowing andsavings opportunities.

69Andreoni and Sprenger (2012a) provide detailed discussion of the use of such background parameters andprovide robustness tests with differing values of ω and differing assumptions for the functional form of utilityin CTB estimates. They provide estimates for ω based on non-linear least squares techniques and analyze theextent to which different assumptions for ω influence remaining parameter estimates. Though utility curvatureand discounting are sensitive to varying assumptions for ω, present bias, β, is largely unaffected. Andersen etal. (2008) also provide some sensitivity analysis.

9

parameters of interest, β, δ and γ at the aggregate and individual level. As our individual

estimates restrict γ to be constant across subjects, this exercise is conducted under various

correlation structures for β and γ to understand the sensitivity of our parameter estimates to

this restriction. Further, the correlation structure also helps to investigate the sensitivity of

identifying β via a non-linear combination involving γ in the aggregate estimates.

Second, we investigate the sensitivity of aggregate and individual estimates to uncertainty.

Subjects may make allocations in Week 1 that minimize their discounted expected cost in fu-

ture weeks given the potential realizations of future parameters. This uncertainty may be

subsequently resolved in Week 2, such that subjects minimize their discounted cost at specific

realizations of key parameters. As the minimizer of the expectation need not be the expectation

of the minimizer, such issues can lead to inconsistencies between initial allocations and subse-

quent allocations. To explore the extent to which this issue hampers identification of present

bias, we conduct simulations under several uncertainty structures.

Our procedure for conducting the first simulation exercise is straightforward. We draw 100

samples of 80 individuals with underlying true parameters drawn from distributions centered

roughly around our aggregate estimates. That is, for each sample β is drawn from a normal

distribution with mean 0.9 and standard deviation 0.2; δ is drawn from a normal distribution

with mean 0.99 and standard deviation 0.2; and γ is drawn from a normal distribution with

mean 1.6 and standard deviation of 0.2. We introduce five correlation structures for the rela-

tionship between β and γ, ρ(β, γ) ∈ {−0.75,−0.25, 0, 0.25, 0.75}. For simplicity and to focus

attention on the sensitivity of present bias we assume ρ(β, δ) = 0 and ρ(δ, γ) = 0 when drawing

each sample.

For each of these correlation structures we conduct two key analyses. First, for every sample

we estimate the aggregate parameters, β, δ and γ. The empirical distribution of β over the

100 samples is summarized by the empirical mean, β, the empirical standard deviation, s(β).

Similar values summarize the empirical distributions of δ and γ. We investigate the extent

to which the estimated values for β correspond to the underlying data generating process by

10

comparing β to the true mean β of 0.9. We also provide a measure of type I error in the form

of the probability of rejecting β = 0.9 from each of our 100 drawn samples, 0.9 /∈ CI(β), and

a measure of type II error in the form of the probability of rejecting β = 1, 1 /∈ CI(β). Table

A1, Panel A provide these analyses. With zero correlation structure we precisely estimate

all parameters close to the true underlying distribution. We reject the truth with probability

around 0.10 and remain powered to reject β = 1. With extreme negative correlation of ρ(β, γ) =

−0.75, this precision is largely unaffected, though with extreme positive correlation of ρ(β, γ) =

0.75 the aggregate estimator falters. We begin to overestimate the extent of present bias

and reject the truth with frequency. This exercise documents the sensitivity of our aggregate

estimates to extreme correlation structures.

Next, we focus on individual estimates. Table A1, Panel A provides the results. In each

sample of 80 observations, we estimate individual parameters based on the fixed effects regres-

sion described in section A. We consider the median and mean level of the individual estimate

βi, βi and βmed

i , and the correlation between the true draw of βi and the estimated value βi,

r(βi, βi). For each of the 100 samples, we construct a correlation coefficient, and present the

average value. Across correlation structures, we estimate broadly correct average and median

values. Importantly, even when the accuracy of the level of behavior deteriorates due to ex-

treme negative correlation between β and γ, we find the correlation between the true βi and βi

remains above 0.9. This indicates that the individual estimates remain capable of identifying

differences across individuals in present bias, providing a solid foundation for our individual

analysis.

The remainder of Table A1 analyzes the effect of uncertainty. We focus on uncertainty in

γ realized only in Week 2. Hence the Week 1 allocations are made under uncertainty that is

resolved in Week 2. To operationalize this exercise we again have β and δ drawn from the

distributions above in advance. However, we assume that in Week 1, subjects do not know

their true γ but optimize subject to the knowledge that γ is drawn from a normal distribution

with mean 1.6 and standard deviation of σ. We consider five values of σ ∈ {0, 0.05, 0.1, 0.2}.

11

In Panel B, we provide aggregate and individual analysis.. Though the aggregate estimates

and error rates are unaffected for the lower value of uncertainty, as parametric uncertainty is

increased, we begin to overestimate β and reject the truth with frequency. A similar pattern

is observed in the individual estimates. Importantly, the presence of parametric uncertainty

greatly reduces the correlation between between the true βi and βi which drops below 0.3 in

the more extreme case.

A natural question is why parametric uncertainty leads towards upward-biased estimates of

β, pushing away from present bias. Intuitively, a subject with parametric uncertainty attempts

to avoid situations of high work under extremely convex cost functions that are rarely realized.

As this encourages subjects to spread their initial allocations, we estimate a more convex cost

function. When the uncertainty is realized, they allocate less evenly over time on average, but

the cost function is required by the estimator to remain constant. This change in behavior in

Week 2 winds up being captured partially in the form of an increased β in our parameter space

of interest.

Table A1: Simulation Exercises

Aggregate Estimates Individual Estimates

Panel A: Simulations: δ ∼ N(0.99, 0.22), β ∼ N(0.9, 0.22), γ ∼ N(1.6, 0.22)Correlation Structure: r(β, γ) ∈ {−0.75,−0.25, 0, 0.25, 0.75}

N β s(β) 0.9 /∈ CI(β) 1 /∈ CI(β) γ δ βi βmed

i r(βi, βi)

r(β, γ)=0 80x100 .8828 .0242 11% 95% 1.552 .9955 .9080 .9077 0.971r(β, γ)=-0.25 80x100 .8884 .0235 11% 98% 1.552 .9960 .9113 .9029 0.965r(β, γ)=-0.75 80x100 .9169 .0235 13% 86% 1.537 .9955 .9359 .9071 0.931r(β, γ)=+0.25 80x100 .8712 .0228 19% 96% 1.556 .9957 .8997 .9116 0.971r(β, γ)=+0.75 80x100 .8541 .0265 45% 96% 1.545 .9953 .8872 .9103 0.964

Panel B: Simulations: δ ∼ N(0.99, 0.22), β ∼ N(0.9, 0.22), γ ∼ N(1.6, σ2)Uncertainty Structure: σ ∈ {0, 0.05, 0.1, 0.2}, Unrealized at Initial Allocation

N β s(β) 0.9 /∈ CI(β) 1 /∈ CI(β) γ δ βi βmed

i r(βi, βi)

σ = 0 80x100 .8800 .0202 13% 94% 1.601 .9957 .9044 .9017 0.995σ = 0.05 80x100 .9001 .0287 7% 92% 1.608 .9949 .9336 .9122 0.824σ = 0.1 80x100 .9593 .0369 26% 17% 1.632 .9952 1.022 .9539 0.590σ = 0.2 80x100 1.186 .0823 98% 58% 1.736 .9957 1.367 1.164 0.325

12

C Discussion of Potential Confounds

Our effort discounting data address several key confounds present in monetary studies, such as

fungibility and arbitrage issues. In this appendix section we address whether we can attribute

the observed behavior for effort choices to dynamic inconsistency. Foremost, the ability to

predict commitment demand based on present-biased allocations gives a degree of confidence

that present-biased allocations are driven by dynamic inconsistency. In the following, we discuss

four additional hypotheses that can generate time inconsistent effort allocations. These are

(unanticipated) permanent shocks to the cost function of performing the tasks, unanticipated

shocks to the cost function in Week 2, general uncertainty in cost functions, and simple mistakes.

Though none of these explanations would predict a correlation between time inconsistency and

commitment demand, we can also address these hypotheses directly.

First, subjects may make present-biased allocations in Week 2 not because they are present-

biased, but because their cost function for the tasks changed permanently. Maybe upon return-

ing to the tasks they find them to be more or less difficult than they previously envisioned. For

example, this could be because they have an injury that makes typing harder, have a bigger

and better (or smaller and worse) screen at home than in the lab, which makes the tasks less

(more) onerous, etc.70 Though we do attempt to give subjects a sense of the tasks, this is a

plausible and critical confound. Our environment is able to address this confound as changes

to perceived cost functions are separable from time preferences. The shape of the cost function

is identified from changes in the value of R. Because both initial allocations and subsequent

allocations are made at various interest rates, the cost function is identified at multiple points

and time. In Appendix Table A10, we estimate cost functions and discounting parameters at

each point in time. We do not find evidence that cost functions change over time.71 This lends

70We see this channel as distinct from the role of uncertainty, as such changes in difficulty need not have beenforecasted.

71The analysis of Appendix Table A10 can be conducted separately for committing and non-committingsubjects to examine if those individuals identified to be dynamically inconsistent in their commitment choicehave varying cost functions or varying discounting parameters over time. For committing subjects the weeklydiscount factor measured in Week 1 is 1.082 (s.e. = 0.051), while the weekly discount factor measured in Week 2is 0.900 (0.037). This difference is significant at the 1% level, χ2(1) = 6.38 (p = 0.01). For committing subjects

13

credence to the notion that changes in cost functions are not driving the observed behavior.72

Second, subjects may reallocate fewer tasks to the present due to an unforeseen, local shock

that resulted in an increase in the cost function in Week 2 only. This could be because the

subject is unusually busy in Week 2 because of a surprise exam, or finds himself unusually

exhausted and hence unusually irritated with the length of work to be done. There are several

ways to address this concern. First, a simple way in which subjects may find it unusually difficult

to complete the work in Week 2 is if they log on to the experimental website so late, just prior

to midnight, that they have only a very limited opportunity to complete their tasks. We can

check for this hypothesis because we recorded the time at which subjects made their allocations.

The median subject completed their allocations in Week 2 with 10.3 hours remaining before

the imposed midnight deadline. Only 4 of 80 subjects completed their allocations in Week 2

with less than 2 hours remaining before the imposed midnight deadline and 0 of 80 completed

their allocations with less than 1 hour remaining. We therefore do not find evidence that a

physical time constraint is a driving force in the allocations.

However, subjects logging on later may indeed be those who experienced an unanticipated

shock in costs (even if their timing does not entail a physical constraint). We therefore examine

whether subjects who log on to our experimental website later in the evening of their Week

2 work date exhibit more present bias. Individuals who log on with less than 4 hours before

midnight (20 percent of our sample) are no more present-biased and have virtually identical

allocation behavior as others.73

the cost function parameter measured in Week 1 is γ = 1.739 (0.184), and in Week 2 is γ = 1.519 (0.121). Thisdifference is not significant at conventional levels, χ2(1) = 2.53 (p = 0.11). This indicates that for subjectsseparately identified as present-biased through their commitment choice, changing behavior through time ismore clearly linked to changing discounting parameters and not changing cost functions. No differences ineither discounting or cost functions are observed between Weeks 1 and 2 for non-committing subjects.

72Note that if cost functions would change over time, and this were the unique driver for changes in allocationsbetween Week 1 and Week 2, we would observe a specific pattern of allocations. If an individual moved fromhaving an almost linear cost function to a very convex one, the corresponding allocations would shift from beingvery price sensitive to limited price sensitivity. When initial allocations asked for lot of work to be done inWeek 2, we would indeed see a change that amounts to a reduction of work in Week 2. However, for allocationsthat asked for little work in Week 2, we would see an increase in work to be done in Week 2. This is not whatwe observe. The data show a universal reduction of work to be allocated in Week 2.

73Subjects logging on with more than 4 hours before midnight allocate an average of 23.80 (s.d = 15.91) tasksto the sooner work date in Week 2, while subjects logging on with less than 4 hours allocate 25.43 (14.06). Even

14

As a final way to assess whether some subjects may have had unusual shocks to their cost

function (and whether these are subjects that generate our results of present-biased allocations),

we can find a proxy for the costs of the tasks in Week 2. Specifically, we examine the amount

of time it takes subjects to complete their minimum work in Week 2. Minimum work took

the median subject around 18 minutes to complete. Those subjects who take longer than 25.7

minutes (20 percent of our sample) are no more present-biased and have virtually identical

allocation behavior as others.74 Naturally, these analyses may not give a fully satisfactory

response to the potential confound presented by forecasting error and boredom. If indeed such

a possibility is the source of our present-biased data patterns, a final question is whether or

not such a hypothesis delivers the observed correlation between present-bias and commitment

demand. We believe the answer to this question to be no.

A third class of explanations which can generate a pattern of present-biased behavior in

the absence of time inconsistency concerns uncertainty in cost functions. When making ini-

tial allocations, subjects do so under a different informational environment than when making

their subsequent allocations. There could be uncertainty for initial allocations, which is par-

tially resolved when allocations are again made one week later. Several aspects of uncertainty

warrant attention. First, individuals may carry preferences for the resolution of uncertainty

(Kreps and Porteus, 1978; Epstein and Zin, 1989; Chew and Epstein, 1989). Unlike monetary

designs, in our effort experiment such a preference may more naturally lead to a future bias.

without accounting for multiple observations this difference is not significant, t(798) = 1.19, p = 0.24. Subjectslogging on with more than 4 hours before midnight have budget share differences between Weeks 1 and 2 of-0.049 (0.21), indicating they allocate around 5 percent less of the budget of tasks to the sooner work date inWeek 2 than they allocated in Week 1. Subjects logging on with less than 4 hours have budget share differencesbetween Weeks 1 and 2 of -0.052 (0.20). Even without accounting for multiple observations this difference isnot significant, t(798) = 0.15, p = 0.88. Note however, that in general, subjects that log in later may be morepresent-biased, as they do everything a little later. And indeed, if we instead cut at the median log-in time, 10.3hours before midnight, marginally significant differences are observed indicating that present-biased individualsmay be logging in later. However, such individuals do not appear to be those particularly close to the deadline.

74Subjects taking less than 25.7 minutes allocate an average of 24.11 (s.d = 15.43) tasks to the sooner workdate in Week 2, while subjects taking more than 25.7 minutes allocate 24.15 (16.11). Even without accountingfor multiple observations this difference is not significant, t(798) = 0.03, p = 0.98. Subjects taking less than25.7 minutes have budget share differences between Weeks 1 and 2 of -0.049 (0.20), indicating they allocatearound 5 percent less of the budget of tasks to the sooner work date in Week 2 than they allocated in Week1.Subjects taking more than 30 minutes have budget share differences between Weeks 1 and 2 of -0.053 (0.22).Even without accounting for multiple observations this difference is not significant, t(798) = 0.23, p = 0.82.

15

Subjects desiring to resolve uncertainty in their subsequent allocation choices could, in prin-

ciple, choose to complete their tasks immediately when the present is available. Second, our

discounting estimates do not account for subjects’ potential uncertainty on their own parame-

ters, such as uncertainty with regards to the future costliness of the task. Though the weekly

parameter estimates provided in Table A10 help to alleviate some concerns, a deeper problem

may exist. Subjects may make allocations in Week 1 that minimize their discounted expected

cost in future weeks given the potential realizations of future parameters. This uncertainty

may be subsequently resolved in Week 2, such that subjects minimize their discounted cost at

specific realizations of key parameters. As the minimizer of the expectation need not be the

expectation of the minimizer, such issues can lead to inconsistencies between initial allocations

and subsequent allocations. To explore the extent to which this issue hampers identification

of present bias, we conduct simulations under a variety of uncertainty structures in Appendix

B. Uncertainty, unresolved at initial allocation and realized at the time of the subsequent al-

location, does bias our estimates of β both at the aggregate and individual level. However,

the direction of bias is generally upward in the parameter regions of interest, leading to less

estimated present bias.75 Importantly, a subject with future uncertainty would benefit from

flexibility, such that even if present bias was delivered by uncertainty of some form one would

not expect a correlation between present bias and commitment demand.

Fifth, present-biased allocations of effort may be a simple decision error. Hence, present

bias, or any dynamic inconsistency, may be an unstable phenomenon. The two blocks of our

experiment speak to this possibility. Subjects have two opportunities to exhibit present-biased

allocations. Indeed, present-biased behavior in Block 1 and Block 2 is significantly correlated.76

At the allocation level, a subject who is present-biased in Block 1 is 58% more likely than others

75 Intuitively, subjects with unresolved uncertainty on future parameters seek to avoid the extreme possibilitiesof working under a very convex cost structure that is only rarely realized. This leads initial allocations to befrequently lower than subsequent allocations, particularly at higher interest rates. Appendix B provides greaterdetail.

76 Though the behavior is significantly correlated when examined as indicators for present bias, future biasand dynamic consistency; the budget share differences are not significantly correlated through time. This maybe due to the sheer volume of data with budget share differences equal to zero and the relative lack of stabilityfor future-biased behavior.

16

to be present-biased in Block 2, F (1, 79) = 6.94, (p = 0.010).77 Additionally, an individual

who is dynamically consistent in Block 1 is 85% more likely to be dynamically consistent in

Block 2 than others F (1, 79) = 50.88, (p < 0.01).78

This discussion helps to clarify some of the potential confounds for our observed effects.

We view it as unlikely that present-biased allocations of effort are driven by unanticipated

permanent or temporary shocks, uncertainty, or decision error. Further, that present bias over

effort exhibits stability and predicts commitment demand gives confidence that our observed

effects are generated by dynamic inconsistency.

D Commitment Value and Sophistication

We analyze the relationship between commitment valuations and sophistication by calculating

V = (1− 2p) · βδt−s · {[(es∗t,t + ω)γ + δkc(es∗t+k,t + ω)γ]− [(e∗t,s + ω)γ + δkc(e∗t+k,s + ω)γ]}.

at the estimated parameter values from Table 3, column (3) of γ = 1.6, δ = 1, and β = 0.9

under various assumptions for the value of β. Differing values of β deliver different forecasted

allocations (es∗t,t, es∗t+k,t) and hence different values of V . As β diverges from 1, forecasted alloca-

tions differ more dramatically from initial allocations and the value of commitment grows. For

each value of V we calculate the equivalent number of tasks as

T γ = V.

77Test statistic from OLS regression of binary indicator for a present-biased allocation in Block 2 on matchedindicator for present-biased allocation in Block 1 with standard errors clustered on the subject level. Theestimated constant is 0.218 (s.e. = 0.030) and the coefficient on Block 1 present bias is 0.128 (s.e. = 0.049).

78 Test statistic from OLS regression of binary indicator for a dynamically consistent allocation in Block2 on matched indicator for a dynamically consistent allocation in Block 1 with standard errors clustered onthe subject level. The estimated constant is 0.400 (s.e. = 0.041) and the coefficient on Block 1 dynamicconsistency is 0.342 (s.e. = 0.048). Interestingly, somewhat less precision is found for future biased allocations.An individual who is future-biased in Block 1 is 54% more likely to be future-biased in Block 2 than othersF (1, 79) = 3.07, (p = 0.08). Test statistic from OLS regression of binary indicator for a future-biased allocationin Block 2 on matched indicator for a future-biased allocation in Block 1 with standard errors clustered onthe subject level. The estimated constant is 0.162 (s.e. = 0.025) and the coefficient on Block 1 future bias is0.088 (s.e. = 0.050).

17

It is useful to go through the calculation similar to that in the main text, solving for T

given a set of parameters. Consider a subject with parameter values γ = 1.6, δ = 1, β = .9, and

ω = 10 (our maintained assumption), optimizing at R = 1 with m = 50 and the experimental

implementation probability of p = .1. Optimization at time s yields e∗t,s = e∗t+k,s = 25. A

subject with βe = .9 perceives that she will choose es∗t,t = 21.9 and es∗t+k,t = 28.1. V can then be

calculated as

V = (0.8) · 0.9 · {[(21.9 + 10)1.6 + (28.1 + 10)1.6]− [(25 + 10)1.6 + (25 + 10)1.6]} = T 1.6

Solving for T yields 1.32 tasks.

This calculation does not take into account the fact that subjects make 10 allocations at

time s. Hence, the value of commitment should be expressed as the expectation of V across

these 10 allocations,

T γ = E[V ] =10∑i=1

1

10Vi.

For simplicity, we ignore the fact that the elicitation of commitment demand entails a second

stage price list randomization procedure.

Using this calculation and the parameters above, it is possible to solve for the equivalent

number of tasks, T , for a given value of β. In Table A2, we calculate T for various values

of β at the parameter values noted above. For each T we also provide the monetary value

of commitment at a wide range of per-task values, w. Note that as β decreases, the value of

commitment increases and that only in the extremes do commitment valuations exceed one or

two dollars.

18

Table A2: Commitment Values, β and Per Task Valuations

Value of Commitment Given Different βEquiv. # of Tasks Monetary

T w = $0.10 w = $0.20 w = $0.30 w = $0.40 w = $0.50(˜$6/hour) (˜$12/hour) (˜$18/hour) (˜$24/hour) (˜$30/hour)

β = 1 0 $0.00 $0.00 $0.00 $0.00 $0.00

β = .9 1.2 $0.12 $0.23 $0.34 $0.46 $0.57

β = .8 2.9 $0.29 $0.59 $0.88 $1.18 $1.47

β = .7 5.3 $0.53 $1.06 $1.59 $2.12 $2.64

β = .6 8.2 $0.82 $1.64 $2.46 $3.28 $4.10

β = .5 11.7 $1.17 $2.35 $3.52 $4.69 $5.87

19

E Additional Tables and Figures

E.1 Tabulations of Dynamic Consistency

The following tables provide tabulations of each experimental interest rate or task rate for

money and effort and two measures of dynamic inconsistency. First, the average budget share

to either the sooner payment or sooner work date is contrasted across allocation timing and,

second, the proportion of subjects who are present-biased, dynamically consistent, and future-

biased is provided. Separate tables are provided for the the full set of experimental data and

the replication exercise.

20

Table A3: Aggregate Behavior By Interest Rate, Full Data Set


P t 6= 0 t = 0 t-test Proportion Proportion ProportionBudget Share Budget Share (p-value) Present-Biased Dynamically Consistent Future-Biased

(1) (2) (3) (4) (5) (6)

0.952 0.924 0.923 0.07 0.073 0.813 0.113(0.228) (0.189) (p=0.94)

1 0.774 0.813 1.32 0.200 0.660 0.140(0.368) (0.323) (p=0.19)

1.11 0.102 0.148 1.86 0.180 0.733 0.087(0.259) (0.300) (p=0.06)

1.25 0.051 0.087 1.97 0.113 0.853 0.033(0.177) (0.239) (p=0.05)

1.429 0.053 0.077 1.40 0.100 0.847 0.053(0.182) (0.228) (p=0.16)

Overall 0.381 0.410 1.87 0.133 0.781 0.085(0.461) (0.458) (p=0.07)


R Initial Subsequent t-test Proportion Proportion ProportionBudget Share Budget Share (p-value) Present-Biased Dynamically Consistent Future-Biased

(1) (2) (3) (4) (5) (6)

0.5 0.796 0.768 2.95 0.291 0.494 0.216(0.179) (0.207) (p<0.01)

0.75 0.729 0.694 3.11 0.375 0.384 0.241(0.208) (0.240) (p<0.01)

1 0.533 0.494 3.87 0.231 0.653 0.116(0.152) (0.181) (p<0.01)

1.25 0.293 0.260 2.74 0.297 0.509 0.194(0.232) (0.235) (p<0.01)

1.5 0.244 0.222 1.81 0.278 0.525 0.197(0.234) (0.231) (p=0.07)

Overall 0.519 0.488 3.90 0.294 0.513 0.193(0.301) (0.311) (p<0.01)

Notes: Panel A tabulates t 6= 0 and t = 0 budget shares for sooner payments for each P in money. Each row

calculates from 75 t 6= 0 allocations (one at each interest rate in the Week 4 vs. Week 7 prospective choices)

and 150 t = 0 allocations (one at each interest rate in the Week 4 vs. Week 7 actual and Week 1 vs. Week 4)

choices. Paired t-tests with 149 degrees of freedom presented. Panel B tabulates initial and subsequent budget

shares for sooner tasks for each R in effort. Each row calculates from 320 initial allocations (one each for tetris

and greek at each task rate in each round) and 320 subsequent allocations. Paired t-tests with 159 degrees of

freedom presented. Overall tests in both panels come from regression of budget share on allocation timing with

standard errors clustered on individual level. Test statistic is t-statistic testing the null hypothesis of no effect

of allocation timing, which controls for multiple comparisons.

21

Table A4: Aggregate Behavior By Interest Rate, Replication Exercise


P Initial Subsequent t-test Proportion Proportion ProportionBudget Share Budget Share (p-value) Present-Biased Dynamically Consistent Future-Biased

(1) (2) (3) (4) (5) (6)

0.666 0.932 0.935 0.39 0.091 0.879 0.030(0.174) (0.182) (p=0.70)

0.8 0.929 0.945 1.77 0.081 0.859 0.061(0.172) (0.153) (p=0.07)

0.909 0.917 0.917 0.03 0.101 0.828 0.071(0.186) (0.194) (p=0.97)

0.952 0.908 0.901 0.55 0.152 0.788 0.061(0.190) (0.206) (p=0.58)

1 0.621 0.695 2.37 0.232 0.667 0.101(0.336) (0.302) (p=0.02)

1.053 0.105 0.084 1.05 0.081 0.828 0.091(0.240) (0.212) (p=0.30)

1.111 0.086 0.088 0.25 0.081 0.869 0.051(0.207) (0.226) (p=0.81)

1.25 0.064 0.064 0.07 0.071 0.869 0.061(0.162) (0.182) (p=0.95)

1.538 0.062 0.048 1.71 0.020 0.879 0.101(0.171) (0.150) (p=0.09)

Overall 0.514 0.520 0.92 0.101 0.829 0.070(0.451) (0.456) (p=0.36)


P Initial Subsequent t-test Proportion Proportion ProportionBudget Share Budget Share (p-value) Present-Biased Dynamically Consistent Future-Biased

(1) (2) (3) (4) (5) (6)

0.666 0.337 0.318 1.09 0.400 0.305 0.295(0.203) (0.232) (p=0.27)

0.8 0.385 0.361 1.25 0.421 0.242 0.337(0.196) (0.223) (p=0.21)

0.909 0.432 0.405 1.21 0.453 0.189 0.358(0.191) (0.219) (p=0.23)

0.952 0.458 0.418 1.96 0.474 0.221 0.305(0.175) (0.220) (p=0.05)

1 0.522 0.507 0.58 0.337 0.358 0.305(0.153) (0.211) (p=0.56)

1.053 0.581 0.554 1.18 0.463 0.200 0.337(0.194) (0.235) (p=0.24)

1.111 0.618 0.566 2.37 0.474 0.211 0.316(0.195) (0.239) (p=0.02)

1.25 0.658 0.603 2.29 0.400 0.253 0.347(0.210) (0.255) (p=0.02)

1.538 0.727 0.667 2.38 0.400 0.305 0.295(0.220) (0.280) (p=0.02)

Overall 0.524 0.489 1.95 0.425 0.254 0.322(0.229) (0.260) (p=0.05)

Notes: Panel A tabulates initial and subsequent budget shares for sooner payments for P in money. Each row

calculates from 99 initial allocations and 99 subsequent allocations choices. Paired t-tests with 98 degrees of

freedom presented. Panel B tabulates initial and subsequent budget shares for sooner tasks for each P in effort.

Each row calculates from 95 initial allocations and 95 subsequent allocations. Paired t-tests with 94 degrees of

freedom presented. Overall tests in both panels come from regression of budget share on allocation timing with

standard errors clustered on individual level. Test statistic is t-statistic testing the null hypothesis of no effect

of allocation timing, which controls for multiple comparisons.

22

E.2 Individual Estimates

We contrast initial and subsequent allocations for work and for money within subjects for the

80 subjects in the primary study sample and the 75 subjects with complete monetary data.

Estimates of present bias for each subject are also provided. Corresponding allocations and

estimates also provided for between subjects replication study.

23

Table A5: Individual Estimates Subjects 1-45

Effort Choices Monetary ChoicesSubject # Mean Initial Mean Subsequent βe Mean Initial Mean Subsequent βm

Budget Share Budget Share Budget Share Budget Share(1) (2) (3) (4) (5) (6)

1 .5 .5 1 .4 .3 1.0462 .496 .476 .952 .527 .537 .9993 .522 .516 .983 .4 .3 1.0464 .534 .498 .86 .309 .354 .9795 .516 .402 .731 .4 .4 16 .514 .512 .995 .4 .4 17 .514 .514 1 .4 .4 18 .576 .472 .742 . . .9 .514 .5 .959 . . .10 .5 .5 1 .4 .4 111 .5 .52 1.078 .4 .4 112 .5 .5 1 .4 .4 113 .628 .486 .664 .4 .4 114 .462 .512 1.143 .3 .456 .93415 .542 .414 .683 .4 .4 116 .5 .5 1 .4 .4 117 .5 .4 .725 .4 .4 118 .468 .404 .796 .4 .3 1.04619 .582 .296 .437 .4 .3 1.04620 .504 .48 .884 .4 .4 121 .51 .424 .739 .4 .4 122 .482 .344 .665 .4 .4 123 .5 .51 1.012 .294 .376 .96424 .832 .512 .426 .4 .415 .99925∗ .56 .518 .815 .4 .3 1.04626 .52 .404 .731 . . .27 .648 .514 .698 .2 .407 .91428 .642 .254 .319 .4 .513 .96129 .588 .51 .724 .2 .3 .95630 .552 .5 .851 .4 .4 131 .51 .498 .961 .3 .4 .95632∗ .432 0 .249 .4 .4 133 .5 .5 1 .4 .4 134 .526 .478 .842 .4 .5 .95735 .496 .4 .723 .2 .35 .93536∗ .516 .522 1.045 .4 .7 .8837 .666 .5 .638 .3 .35 .97838 .792 .746 .879 .457 .5 .98339 .514 .54 1.072 .51 .45 1.0240 .516 .516 1 .4 .4 141 .536 .51 .945 .206 .428 .9142 .6 .6 1 .4 .4 143 .514 .512 .995 .4 .666 .89744 .522 .514 .976 .531 .532 145 .514 .51 .991 .4 .3 1.046

Notes: Tabulates initial and subsequent budget shares for both effort and money and corresponding present

bias estimates for subjects 1-45 of 89 non-attriting subjects and 84 subjects with complete monetary data. Nine

subjects excluded from primary sample marked with ∗. Subject 25 provided no variation in response in Weeks

4 or 5. Subject 32 provided no variation in Week 2. Subject 36 provided no variation in Week 5.

24

Table A6: Individual Estimates Subjects 46-89

Effort Choices Monetary ChoicesSubject # Mean Initial Mean Subsequent βe Mean Initial Mean Subsequent βm


46 .512 .36 .654 .509 .743 .9147∗ .34 .27 .818 .4 .3 1.04648 .508 .518 1.024 .4 .4 149∗ .514 .516 1.006 .4 .4 150∗ 1 .844 .603 .4 .3 1.04651 .59 .692 1.174 0 .2 .91352 .548 .5 .979 .4 .4 153 .506 .38 .686 .403 .306 1.04454 .5 .5 1 .4 .4 155 .514 .514 1.003 .4 .147 1.12156 .354 .444 1.32 .201 .256 .97657 .896 .502 .291 .4 .4 158 .512 .504 .983 .203 .405 .9259 .474 .48 1.027 .4 .4 160 .24 .21 .876 .4 .4 161 .5 .6 1.379 .4 .4 162 .518 .5 1.086 .4 .8 .84263 .57 .5 .788 .4 .45 .97964 .55 .6 1.174 .2 .4 .91465 .5 .4 .725 .2 .3 .95666 .604 .524 .788 .4 .4 167 .42 .4 .957 . . .68 .546 .552 1.019 0 .471 .81469∗ .4 0 .238 .4 .4 170 .47 .5 1.132 .6 .4 1.09271 .46 .476 1.092 .6 .5 1.04572∗ .22 0 .429 .539 .851 .87373 .512 .516 1.005 .2 .198 1.00174 .5 .5 1 .4 .4 175 .44 .51 1.203 .4 .35 1.02376 .544 .506 .802 1 .5 1.23677 .594 .626 1.114 .2 .2 178 .52 .5 .964 .4 .4 179 .53 .518 .973 .52 .5 1.00780 .72 .056 .14 .9 .959 .97381 .542 .508 .912 .499 .409 1.04182∗ .754 1 2.629 .2 .1 1.04783 .5 .49 .973 . . .84 .512 .5 1.107 .4 .4 185 .504 .538 1.091 .4 .4 186 .46 .504 1.12 0 .303 .8787 .514 .458 .935 .4 .4 188 .51 .51 1.003 .4 .4 189 .5 .5 1 .4 .5 .957

Notes: Tabulates initial and subsequent budget shares for both effort and money and corresponding presentbias estimates for subjects 51-89 of 89 non-attriting subjects and 84 subjects with complete monetary data.Nine subjects excluded from primary sample marked with ∗. Subject 47 provided no variation in response inWeek 5. Subject 49 provided no variation in Week 5. Subject 50 provided no variation in Week 1. Subject 69provided no variation in Week 2. Subject 72 provided no variation in Weeks 2, 4 or 5. Subject 82 provided novariation in Weeks 2 or 5.

25

Table A7: Replication Study Individual Estimates Subjects 1-50

Effort Choices Monetary ChoicesSubject # Mean Initial Mean Subsequent βe Subject # Mean Initial Mean Subsequent βm


1 .444 .556 1.502 1 .499 .555 .9652 .528 .774 2.126 2 .444 .444 13 .556 .552 .958 3 .55 .495 1.0364 .463 .5 1.12 4 .492 .532 .9785∗ .072 0 .753 5 .522 .527 .9976∗ .578 .258 .369 6 .555 .555 17 .575 .556 .888 7 .555 .666 .9328 .5 .5 1 8 .497 .502 .9979∗ .258 .606 2.835 9 .555 .555 110 .509 .501 .98 10 .499 .499 111 .542 .423 .703 11 .489 .499 .99112 .484 .523 1.129 12 .555 .555 113 .427 .25 .586 13 .555 .555 114 .502 .502 1 14 .555 .555 115 .579 .593 1.043 15 .301 .444 .90916 .556 .444 .666 16 .499 .499 117 .693 .553 .647 17 .555 .555 118∗ .499 .504 1.002 18 .499 .499 119 .665 .603 .84 19 .507 .438 1.04420 .509 .362 .644 20∗ .497 .499 .99921 .526 .31 .527 21 .345 .363 .98922 .558 .441 .674 22 .555 .555 123 .494 .487 .976 23 .5 .501 124 .423 .475 1.144 24 .499 .499 125 .508 .53 1.076 25 .499 .555 .96526 .502 .506 1.022 26 .499 .499 127 .402 .39 .963 27 .499 .499 128 .5 .5 1 28 .499 .499 129 .529 .553 1.072 29 .555 .418 1.09730 .283 .486 1.824 30 .499 .501 .99931 .551 .486 .827 31 .444 .555 .93132∗ .498 .83 2.87 32 .499 .488 1.00633∗ .509 1 6.087 33 .499 .555 .96534 .598 .621 1.103 34 .444 .555 .93135 .518 .505 .959 35 .499 .499 136 .527 .407 .727 36 .499 .499 137 .604 .659 1.181 37 .555 .499 1.03638 .814 .798 .906 38 .555 .555 139 .509 .52 1.04 39 .499 .499 140 .528 .537 .98 40 .555 .555 141 .507 .506 .999 41 .444 .555 .93142∗ .52 0 .153 42 .499 .555 .96543∗ .747 0 .071 43 .494 .555 .9644 .561 .504 .818 44 .499 .499 145∗ .68 0 .091 45 .555 .555 146 .517 .598 1.422 46 .666 .452 1.14847 .486 .518 1.157 47 .499 .499 148 .5 .502 1.005 48 .499 .499 149 .568 .742 1.776 49 .444 .444 150 .488 .51 1.064 50 .499 .555 .965

Notes: Tabulates initial and subsequent budget shares and corresponding present bias estimates for both effortand money for between subjects data for first 50 of 99 money subjects and first 50 of 94 effort subjects

26

Table A8: Replication Study Individual Estimates Subjects 51-99

Effort Choices Monetary ChoicesSubject # Mean Initial Mean Subsequent βe Subject # Mean Initial Mean Subsequent βm


51 .505 .741 2.438 51 .503 .481 1.01352 .493 .493 1 52 .465 .536 .96153 .632 .591 .863 53 .555 .555 154 .5 .502 1 54 .555 .555 155 .411 .333 .805 55 .493 .534 .97756 .588 .542 .866 56∗ .699 .337 1.19957 .296 .334 1.112 57 .555 .555 158 .538 .526 .924 58 .555 .555 159 .574 .514 .826 59 .555 .555 160 .502 .499 .985 60 .555 .555 161 .574 .586 1.027 61 .555 .499 1.03662 .685 .654 .831 62 .555 .555 163 .794 .528 .369 63 .555 .555 164 .448 .46 1.043 64 .499 .499 165 .554 .53 .892 65 .555 .555 166 .493 .491 .992 66 .444 .499 .96567 .5 .498 1 67 .555 .555 168 .505 .516 1.03 68 .562 .617 .97169 .574 .632 1.188 69 .499 .499 170 .433 .348 .777 70 .555 .545 1.00971 .489 .499 1.028 71 .444 .555 .93172 .595 .551 .885 72 .476 .515 .97373 .496 .516 1.053 73 .555 .555 174 .512 .176 .353 74 .72 .749 .97675 .462 .476 .994 75 .444 .555 .93176 .49 .603 1.39 76 .499 .555 .96577∗ .67 .67 1.011 77 .444 .444 178 .572 .553 .983 78 .555 .555 179 .755 .273 .231 79 .555 .555 180 .503 .512 1.016 80 .499 .499 181∗ .283 0 .308 81 .777 .666 1.07382 .477 .503 1.076 82 .503 .512 .99583 .634 .341 .424 83 .499 .499 184∗ .344 .501 1.577 84 .384 .477 .95385∗ .667 .667 1 85 .555 .555 186 .517 .509 .982 86 .499 .499 187 .497 .48 .955 87 .444 .499 .96588∗ .516 .597 1.321 88 .444 .499 .96589 .505 .504 .995 89 .555 .555 190 .528 .539 1.033 90 .533 .533 1.00691 .503 .401 .753 91 .289 .281 1.00592 .641 .506 .677 92 .444 .555 .93193 .514 .495 .951 93 .555 .555 194 .571 .518 .862 94 .499 .499 195 .581 .243 .364 95 .499 .499 1

96 .472 .383 1.04897 .499 .499 198 .444 .444 199 .666 .555 1.073

Notes: Tabulates initial and subsequent budget shares and corresponding present bias estimates for both effortand money for between subjects data for subjects 51-99 of 99 money subjects and first 51-94 of 94 effort subjects

27

E.3 Estimates Including Nine Subjects With Limited Effort Alloca-

tion Variation

We re-conduct the primary aggregate analysis including 9 subjects with limited variation in

their effort allocation choices.

Table A9: Parameter Estimates Including 9 Additional Subjects







# Observations 1680 1260 890 890 1780# Clusters 84 84 89 89 89Job Effects Yes

H0 : β = 1 χ2(1) = 9.09 χ2(1) = 2.12 χ2(1) = 8.41 χ2(1) = 13.39 χ2(1) = 12.23(p < 0.01) (p = 0.15) (p < 0.01) (p < 0.01) (p < 0.01)

H0 : β(Col. 1) = β(Col. 5) χ2(1) = 11.45(p < 0.01)

H0 : β(Col. 2) = β(Col. 5) χ2(1) = 13.79(p < 0.01)

Notes: Parameters identified from two-limit Tobit regressions of equations (4) and (6) formonetary discounting and effort discounting, respectively. Parameters recovered via non-linearcombinations of regression coefficients. Standard errors clustered at individual level reportedin parentheses, recovered via the delta method. Effort regressions control for Job Effects (Task1 vs. Task 2). Tested null hypotheses are zero present bias, H0 : β = 1, and equality of presentbias across effort and money, H0 : β(Col. 1) = β(Col. 5) and H0 : β(Col. 2) = β(Col. 5).

28

E.4 Estimates For Effort Discounting By Week

We re-estimate parameters by week and test the null hypothesis of equality of discount rates

identified from initial allocations and subsequent allocations.

Table A10: Parameter Estimates By Week

Effort Discounting

(1) (2) (3) (4)Week 1 Week 2 Week 4 Week 5

Initial Allocations Subsequent Allocations Initial Allocations Subsequent Allocations


Cost of Effort Parameter: γ 1.668 1.521 1.463 1.528(0.126) (0.097) (0.074) (0.092)

# Observations 800 800 800 800# Clusters 80 80 80 80Job Effects Yes Yes Yes Yes

H0 : (δ)7(Col. 1) = (δ)7(Col. 2) χ2(1) = 7.02(p < 0.01)

H0 : (δ)7(Col. 3) = (δ)7(Col. 4) χ2(1) = 4.10(p = 0.04)

Notes: Parameters identified from two-limit Tobit regressions of equation (6) assuming β = 1 foreffort discounting. Parameters recovered via non-linear combinations of regression coefficients.Standard errors clustered at individual level reported in parentheses, recovered via the deltamethod. Effort regressions control for Job Effects (Task 1 vs. Task 2). Tested null hypothesesare equal discounting in Weeks 1 vs. 2 and Weeks 4 and 5, H0 : (δ)7(Col. 1) = (δ)7(Col. 2) andH0 : (δ)7(Col. 3) = (δ)7(Col. 4).

29

E.5 Full Effort Data Set Tables Figures

We reconduct all analyses using Block 1 and Block 2 data to identify effort discounting param-

eters.

Table A11: Parameter Estimates: Full Effort Data Set







# Observations 1500 1125 1600 1600 3200# Clusters 75 75 80 80 80Block Effects Yes Yes YesJob Effects Yes

H0 : β = 1 χ2(1) = 8.77 χ2(1) = 1.96 χ2(1) = 11.1 χ2(1) = 11.9 χ2(1) = 13.94(p < 0.01) (p = 0.16) (p < 0.01) (p < 0.01) (p < 0.01)

H0 : β(Col. 1) = β(Col. 5) χ2(1) = 5.46(p = 0.02)

H0 : β(Col. 2) = β(Col. 5) χ2(1) = 8.61(p < 0.01)

Notes: Parameters identified from two-limit Tobit regressions of equations (4) and (6) formonetary discounting and effort discounting, respectively. Parameters recovered via non-linearcombinations of regression coefficients. Standard errors clustered at individual level reported inparentheses, recovered via the delta method. Effort regressions control for Block Effects (Weeks1,2,3 vs. 4,5,6) and Job Effects (Task 1 vs. Task 2). Tested null hypotheses are zero present bias,H0 : β = 1, and equality of present bias across effort and money, H0 : β(Col. 1) = β(Col. 5)and H0 : β(Col. 2) = β(Col. 5).

30

Table A12: Monetary and Real Effort Discounting by Commitment: Full Effort Data Set


Commit (=0) Commit (=1) Commit (=0) Commit (=1)

(1) (2) (3) (4)Tobit Tobit Tobit Tobit

Present Bias Parameter: β 0.999 0.981 0.989 0.880(0.010) (0.013) (0.018) (0.031)



Cost of Effort Parameter: γ 1.485 1.579(0.123) (0.116)

# Observations# Clusters 28 47 33 47Block Effects Yes YesJob Effects Yes Yes

H0 : β = 1 χ2(1) = 0.01 χ2(1) = 2.15 χ2(1) = 0.34 χ2(1) = 15.12(p = 0.94) (p = 0.14) (p = 0.56) (p < 0.01)

H0 : β(Col. 1) = β(Col. 2) χ2(1) = 1.29(p = 0.26)

H0 : β(Col. 3) = β(Col. 4) χ2(1) = 9.35(p < 0.01)

Notes: Parameters identified from two-limit Tobit regressions of equations (4) and (6) for mon-etary discounting and real effort discounting. Parameters recovered via non-linear combinationsof regression coefficients. Standard errors clustered at individual level reported in parentheses,recovered via the delta method. Commit (=1) or Commit (=0) separates individuals into thosewho did (1) or those who did not (0) choose to commit at a commitment price of zero dollars.Effort regressions control for Block Effects (Weeks 1,2,3 vs. 4,5,6) and Job Effects (Job 1 vs. Job2). Tested null hypotheses are zero present bias, H0 : β = 1, and equality of present bias acrosscommitment and no commitment, H0 : β(Col. 1) = β(Col. 2) and H0 : β(Col. 3) = β(Col. 4).

31

E.6 Replication Exercise Additional Tables

Table A13: Replication Exercise Parameter Estimates, Restricted Sample

Monetary Discounting Effort DiscountingGreek

(1) (2))

Present Bias Parameter: β 0.995 0.934(0.004) (0.035)

Weekly Discount Factor: (δ)7 0.989 1.077(0.005) (0.032)

Monetary Curvature Parameter: α 0.955(0.009)

Cost of Effort Parameter: γ 1.733(0.169)

# Observations 1746 1458# Clusters 97 81

H0 : β = 1 χ2(1) = 1.13 χ2(1) = 3.60(p = 0.29) (p = 0.06)

H0 : β(Col. 1) = β(Col. 2) χ2(1) = 3.07(p = 0.08)



Standard errors clustered at individual level reported in parentheses, recovered via the delta method. Chi-

squared tests used in last two rows. Sample restricted to those individuals with positive variation in experimental

response in both weeks of replication exercise. Excluded subjects noted with ∗ in Appendix Tables A7 and A8

32

Figure A1: Real Effort Discounting Behavior: Full Effort Data Set

1020

3040

.5 1 1.5 .5 1 1.5




Task

s Al

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ted

to E

arly

Dat

e

R(from et+Ret+k=50)

Graphs by task

Figure A2: Individual Estimates of Present Bias: Full Effort Data Set

0.2

.4.6

Frac

tion


0.2

.4.6

Frac

tion

.5 .75 1 1.25 1.5Monetary Present Bias

.8.9

11.

11.2

Mon

etar

y Pr

esen

t Bia

s


33

Figure A3: Commitment Demand: Full Effort Data Set

Panel A: Commit (=0)10

2030

40

.5 1 1.5 .5 1 1.5




Task

s Al

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to E

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Dat

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Graphs by task

Panel B: Commit (=1)

1020

3040

.5 1 1.5 .5 1 1.5




Task

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Graphs by task

34

F Instructions

F.1 Week 1 Effort Instructions

Welcome:

Thank you for participating in our experiment. We will begin shortly.

Eligibility for this study:

To be in this study, you need to meet these criteria: You must be willing to participate for six

consecutive weeks. Participation will require your presence on six consecutive Thursdays for at

least 10 minutes per week for an average of 60 minutes. Weeks 1 (today) and 4 will occur in

the xlab. Weeks 2,3,5, and 6 will occur at any computer that has access to the Internet.

You must be willing to receive your payment from this experiment as one single completion

payment at the end of the study. Payments will be made one week after the final session, on

Thursday, March 22. You will return to the xlab to receive this payment.

If you do not meet these criteria, please inform us of this now.

Informed Consent

Placed in front of you is an informed consent form to protect your rights as a subject. Please

read it. If you would like to choose not to participate in the study you are free to leave at this

point. If you have any questions, we can address those now. We will pick up the forms after

the main points of the study are discussed.

Anonymity

Your anonymity in this study is assured. Your name will never be recorded or connected to

any decision you make here today. Your email will be collected in order to send reminder

emails. After the study, your email information will be destroyed and will not be connected to

your responses in the experiment.

1

Rules

Please turn your cell phones off. If you have a question at any point, just raise your hand.

Please put away any books, papers, computers, etc. There will be a quiz once we have finished

with the instructions. If it is clear that you do not understand the instructions when we review

your answers, you will be emailed and removed from the study.

Your Earnings

If you complete all six weeks of participation, a completion payment of $100 will be provided.

You may receive additional earnings during the experiment. If you choose to end your partic-

ipation before the six weeks are complete, please report this to study administrators, and you

will receive a minimum payment of $10.

All payments will be made one week after the final session, on Thursday March 22. You

will return to the xlab to receive this payment.

Jobs

In this study there are two types of jobs, Job 1 and Job 2. These jobs will be completed over

time. Some portion of the jobs may be completed sooner, and some portion of the jobs may be

completed later depending on your choices and chance. Importantly, some tasks for each job

must be completed in each week. That is, as mentioned before, your participation is required

in each of the six consecutive weeks of the study.

Job 1:

In Job 1 you are asked to transcribe letters from a greek text. Greek text will appear in

the Transcription Box on your screen. For each letter you will need to find and select the

corresponding letter and enter it into the Completion Box on your screen. One task is one row

of greek text. For the task to be complete your accuracy must be 80% or better.

2

Job 2:

In Job 2 you are asked to play a tetris game. Blocks of different shapes drop from the top of

the task screen into a box. Each block is made up of four small squares arranged to make a

larger square, an L-shape or a column. As the blocks fall they can be rotated (by pressing the

up arrow key), moved horizontally (by pressing the left and right arrow keys), or moved down

more quickly (by pressing the down arrow key). Your goal is to fill a entire horizontal line

with parts of the blocks. When a horizontal line is filled, that line is ”destroyed,” moving the

rest of the placed pieces down by one square. If a line remains incomplete, another line must

be finished above it. The more lines that stand incomplete, the higher the blocks above them

stack, reducing the space in which falling shapes can be manipulated. Eventually the blocks

reach the top of the screen and the game ends. One task will be 4 lines of blocks completed. If a

game ends before a task is complete, the completed lines will be counted in the subsequent game.

Practice: We will now spend a few minutes practicing both jobs on the computer. Before

we continue, you will be asked to register using your email by clicking ”register” once you open

the experiment. Make sure that you enter a valid email address.

3

The Experiment Timeline

Now that you’ve tried Job 1 and Job 2, let’s consider the timeline of the study. Along the way

we will discuss a few important details of how the study works.

Note: Minimum Work for each week

In each week (including today), you are required to complete a minimum number of tasks of

both Job 1 and Job 2.

Today (Week 1):

Once your minimum work is complete, you will be asked to make a series of 5 decisions for each

job. In these decisions you are asked to allocate tasks between one week from today (Week 2)

and two weeks from today (Week 3). You will make 5 decisions for both Job 1 and Job 2.

In each decision you are free to allocate your tasks as you choose. Note that this allocation

decision does not include the minimum work for each week, which you must also complete.

You will choose by moving a slider to your desired allocation. We will now practice on the

computer.

4

Task Rates:

In the example decision above every task you allocate to Week 2 reduces the number of tasks

allocated to Week 3 by one. This is what we will refer to as a 1:1 task rate. The task rate

will vary across your decisions. For example, the task rate may be 1:1.5, such that every task

you allocate to Week 2 reduces the number of tasks allocated to Week 3 by 1.5. Or, the task

rate may be 1:0.5, such that every task you allocate to Week 2 reduces the number of tasks

allocated to Week 3 by 0.5. For simplicity, the task rates will always be represented as 1:X,

and you will be fully informed of the value of X when making your decisions. Please practice

with the different allocations using the computer.

5

Week 2 (One Week From Today):

Week 2, one week from today, will occur online. You will receive an email with instructions on

how to access the website with the jobs. You will again complete your minimum work. You

will be asked again to make 5 allocation decisions for each job. Exactly one of your 20 total

allocation decisions will be implemented. That is, we will implement one decision from Week

1 for Job 1, or one decision from Week 2 for Job 1, or one decision from Week 1 for Job 2, or

one decision from Week 2 for Job 2.

We will discuss how this allocation decision is chosen shortly. We refer to this allocation

decision as the ”decision-that-counts.” The tasks you allocated to Week 2 in the decision-

that-counts must be completed. If you do not return or do not complete the tasks in Week

2, you cannot complete the study, and you will receive only the minimum payment of $10.

In order for your tasks in Week 2 to be counted, they must be submitted by midnight on

February 16th, 2012.

6

Week 3, Two Weeks From Today:

Week 3, two weeks from today, will occur online. You will receive an email with instructions

on how to access the website with the jobs. You will again complete your minimum work.

Then, you must complete the tasks you allocated in the decision-that-counts. If you do not

return or do not complete the tasks in Week 3, you cannot complete the study, and you will

receive only the minimum payment of $10. In order for your tasks in Week 3 to be counted,

they must be submitted by midnight on February 23rd, 2012.

Choosing the Decision-That-Counts:

To summarize: In Week 1 (today), you will make 5 allocation decisions for both Job 1 and Job

2 for different task rates. In Week 2, you will also make 5 allocation decisions for both Job 1

and Job 2 for different task rates.

Therefore, you will make 20 total allocation decisions. As stated above, we will choose

only one of these decisions as the decisions-that-counts. That is, we will either implement one

decision from Job 1 or one decision from Job 2, but not both.

There are three stages to determine the decision-that-counts.

1. First, we will choose if the decision-that-counts will come from Week 1 or Week 2. To do

this, we will pick a random number from 1 to 10. If the number is 1, then the decision-

that-counts will come from your Week 1 allocations. If the number is 2,3,4,5,6,7,8,9 or

10, then the decision-that-counts will come from your Week 2 allocations. Therefore, the

decision-that-counts will come from Week 1 with a 10 percent chance and the decision-

that-counts will come from Week 2 with a 90 percent chance.

2. Second, we will choose if the decision-that-counts will come from Job 1 or Job 2. To

do this we will pick a second random number from 1 to 2. If the number is 1 then the

decision-that-counts will come from Job 1. If the number is 2, then the decision-that-

counts will come from Job 2. Therefore, the decision-that-counts is equally likely to come

7

from Job 1 and Job 2.

3. Third, we will choose the decision-that-counts from the 5 allocations you made in the

chosen week and the chosen job. To do this, we will pick a third random number from 1

to 5. Therefore, within the chosen week and chosen job, every allocation is equally likely

to be chosen as the decision-that-counts.

For example, consider the following allocation examples. Imagine that your allocations

were shown in the following diagram for Weeks 1 and 2. Now, imagine that we determine the

decision-that-counts.

Week 1 Allocations

Week 2 Allocations

1. Following the first step above, we would first generate a random number from 1 to 10

to determine whether the Week 1 or the Week 2 allocations will be implemented. If the

8

number is 1, then the decision-that-counts will come from your Week 1 allocations. If

the number is 2,3,4,5,6,7,8,9 or 10, then the decision-that-counts will come from your

Week 2 allocations. Imagine the number is 7, such that your Week 2 allocations will be

implemented.

2. Following the second step above, we would generate a random number from 1 to 2 to

determine the job of the decision-that-counts. If the number is 1 then the decision that

counts will come from Job 1. If the number is 2, then the decision that counts will

come from Job 2. Imagine the number is 1, such that the your Job 1 allocations will be

implemented.

3. Following the third step above, we would generate a random number from 1 to 5 to

determine the decision-that-counts from your Week 2 allocations for Job 1. Imagine this

number is 3 such that the decision-that-counts would then be third allocation

decision from your Week 2 allocations for Job 1

In Week 2, you would be required to complete 27 tasks of Job 1 and in Week

3 you would be required to complete 23 tasks of Job 1.

Note that these tasks will be in addition to the minimum work that you will

be required to complete for both jobs in both weeks.

REMEMBER: EACH DECISION COULD BE THE

DECISION-THAT-COUNTS SO TREAT EACH DECISION AS IF IT WAS

THE ONE DETERMINING YOUR TASKS.

9

Recap:

• You will be participating in a six week study that requires participation one day per week

on six consecutive weeks.

• You will receive a completion payment of $100 at the end of the study by check one week

after Week 6. You will return to the xlab on March 22, 2012 to receive this payment.

• If you choose to no longer participate, or do not complete the jobs you chose, you will

receive only a minimum payment of $10 by check one week after Week 6. You will return

to the xlab on March 22, 2012 to receive this payment.

• There are two possible jobs in the study. Job 1 is transcription of greek letters. Job 2 is

a tetris game.

• In each week, you will be asked to complete minimum work for each job.

• In Week 1, today, you will be asked to make a series of allocation decisions for both Job

1 and Job 2. You will allocate tasks to Weeks 2 and 3 at various task rates.

• In Week 2, you will again make allocation decisions.

• One of your allocation decisions will be chosen at random as the decision-that-counts and

your allocation will determine the tasks that you complete in Weeks 2 and 3.

• One of your Week 1 allocations will be implemented with 10 percent chance while one of

your Week 2 allocations will be implemented with 90 percent chance.

• Weeks 4, 5, and 6 will mirror Weeks 1, 2, and 3. In Week 4 you will make allocation

decisions. In Week 5, you will again make allocation decisions and one of your allocation

decisions will be chosen at random as the decision-that-counts. Your allocation will

determine the jobs that you complete in Weeks 5 and 6.

10

• One week after week 6, you will receive your completion payment of $100. You will return


11

Consent

Now that we have explained the study, you are free to leave if you would like to choose not to

participate in the study. Otherwise, please sign the consent form and we will pick these up now.

Minimum Work

Now you will complete your minimum work for each job for this week. For each job, we ask

that you complete 10 tasks.

Reminder of Timeline

Today you will be asked to make a series of 5 allocation decisions for both Job 1 and Job 2. In

these decisions you are asked to allocate tasks between one week from today (Week 2) and two

weeks from today (Week 3).

In each decision you are free to allocate your tasks as you choose. The allocations do not

include the minimum amount of work for each job. You will choose by moving a slider to your

desired allocation.

Allocations

In the sliders on the screen, you will be asked to make 5 allocations for Job 1. Then, you will

be asked to make 5 allocation decisions for Job 2.

Remember each decision could be the decision-that-counts, so please make each decision as

if it were the one that determines your tasks.

12

F.2 Week 1 Money Instructions

Thank you for completing your allocations. On the following screens we would like to ask

you several additional questions allocating money over time. Your decisions in this portion of

the study are completely unrelated to your allocations over Job 1 and Job 2 and will be paid

separately.

You must be willing to receive your payment for this study by cash provided to you in the

xlab by Professor Ned Augenblick of the Haas School of Business. You will be required to

return to the xlab on the dates indicated to complete the study and so your choice of payments

will not require you to arrive any extra times.

Earning Money

To begin, you will be given a $10 thank-you payment, just for participating in this study! You

will receive this thank-you payment in two equally sized payments of $5 each. The two $5

payments will come to you at two different times. These times will be determined in the way

described below.

In this portion of the study, you will make 15 choices over how to allocate money between

three possible dates:

1) February 9th (today - week 1),

2) March 1st (three weeks from today - week 4)

3) March 22nd (six weeks from today - week 7).

Note that these are all days that you will be in the xlab. In each decision, you will allocate

money between two of these dates. In the first set of five decisions, you will allocate money

between week 1 (today) and week 4. In the second set, you will allocate money between week

1 (today) and week 7. In the third set, you will allocate money between week 4 and week 7.

This means you could be receiving payments as early as today, and as late as the week 7.

Once all 15 decisions have been made, we will randomly select one of the 15 decisions as the

decision-that-counts. We will use the decision-that-counts to determine your actual earnings.

13

Note, since all decisions are equally likely to be chosen, you should make each decision as if it

will be the decision-that-counts.

When calculating your earnings from the decision-that-counts, we will add to your earnings

the two $5 thank you payments. Thus, you will always get paid at least $5 at the chosen

earlier time, and at least $5 at the chosen later time.

IMPORTANT: All payments you receive will be paid in cash in the xlab. On the

scheduled day of payment, you will come to the xlab for the regular schedule of the study.

Hence, you will not be asked to make any special arrangements to receive payment from this

portion of the study. You will receive your payment from Professor Ned Augenblick.

On your desk are two envelopes: one for the sooner payment and one for the later payment.

Please take the time now to write your participant ID on them.

14

How It Works:

In the following three screens you are asked to make 15 decisions involving payments over time.

Each row is a decision and is numbered from 1 to 15.

Each row will feature a series of options. Each option consists of a sooner payment AND a

later payment. You are asked to pick your favorite option in each row by moving the slider to

your desired location. You should pick the combination of sooner payment AND later payment

that you prefer the most.

Note that there is a trade-off between the sooner payment and the later payment. As the

sooner payment goes down, the later payment goes up. All you have to do for each decision

is choose which combination of sooner and later payment you prefer the most by moving the

slider to that location.

Once all 15 of your decisions are complete, we will choose one at random to be the decision-

that-counts. Your chosen allocation will be implemented.

Consider if the decision-that-counts was the third decision, and in that decision, you

allocated $11 on February 9th and $10.50 on March 1st. Then, on February 9th, we would

place $11 along with your $5 minimum payment, making $16.00, into your first envelope. This

envelope will be given to you on February 9th (today) in the xlab. On March 1st, we would

place $10.50 along with your $5 minimum payment, making $15.50, into your second envelope.

This envelope will be given to you on March 1st when you return to the xlab. Recall that

this will not require you to make any special arrangements to receive payment as you will be

returning to the laboratory as part of the regular schedule of the study.

Once your payments have been determined, you will write the amounts and dates on the

inside of the two envelopes. When you receive your payments you can guarantee there have

been no clerical errors by checking against the amounts and dates you wrote.

15

Remember that each decision could be the decision-that-counts! It is in your in-

terest to treat each decision as if it could be the one that determines your payment.

16

F.3 Week 1 Quiz

Quiz

Please complete the quiz in order to make sure that you understand the allocation decisions

and the timeline of the study.

Participant #

1. How many weeks are you required to participate?

2. In which weeks are you asked to come to the xlab to participate?

3. In which weeks are you asked to participate online and not come to the xlab?

4. Will you have to complete minimum work for each job in each week?

5. You will make allocation decisions for Weeks 2 and 3 both today and in Week 2. What

is the percent chance that one of your Week 2 allocations will be implemented?

6. If you face a 1:2 task rate for allocations between Weeks 2 and 3, every task you allocate

to Week 2 decreases by how many the number of tasks you allocate to Week 3?

7. You will make allocations for each job. Apart from your minimum work, will you complete

any tetris tasks if a transcription job allocation is chosen as the decision-that-counts.

17

F.4 Week 4 Effort Instructions

Welcome:

Thank you for returning to the experiment. We will begin shortly.

Eligibility for this study:

To continue in this study, you need to meet these criteria: You must be willing to participate for

three consecutive weeks. Participation will require your presence on three consecutive Fridays

for at least 10 minutes per week for an average of 60 minutes. Week 4 (today) will occur in the

xlab. Weeks 5 and 6 will occur at any computer that has access to the Internet.

You must be willing to receive your payment from this experiment as one single completion

payment at the end of the study. Payments will be made one week after the final session, on

Friday, March 23. You will return to the xlab to receive this payment.

If you do not meet these criteria, please inform us of this now.

Your Earnings

If you complete all six weeks of participation, a completion payment of $100 will be provided.

You may receive additional earnings during the experiment. If you choose to end your partic-

ipation before the six weeks are complete, please report this to study administrators, and you

will receive a minimum payment of $10.

All payments will be made one week after the final session, on Friday March 23. You will

return to the xlab to receive this payment.

Jobs

In this study there are two types of jobs, Job 1 and Job 2. These jobs will be completed over

time. Some portion of the jobs may be completed sooner, and some portion of the jobs may be

completed later depending on your choices and chance. Importantly, some tasks for each job

must be completed in each week. That is, as mentioned before, your participation is required

18

in each of the six consecutive weeks of the study.

Job 1:

In Job 1 you are asked to transcribe letters from a greek text.

Job 2:

In Job 2 you are asked to play a tetris game.

19

The Experiment Timeline

Note: Minimum Work for each week

In each week (including today), you are required to complete a minimum number of tasks of

both Job 1 and Job 2.

Today (Week 4):

Once your minimum work is complete, you will be asked to make a series of 5 decisions for each

job. In these decisions you are asked to allocate tasks between one week from today (Week 5)

and two weeks from today (Week 6). You will make 5 decisions for both Job 1 and Job 2.

In each decision you are free to allocate your tasks as you choose. Note that this allocation

decision does not include the minimum work for each week, which you must also complete.

Task Rates:

For one example task rate, every task you allocate to Week 6 reduces the number of tasks

allocated to Week 5 by one. This is what we will refer to as a 1:1 task rate. The task rate

will vary across your decisions. For example, the task rate may be 1:1.5, such that every task

you allocate to Week 6 reduces the number of tasks allocated to Week 5 by 1.5. Or, the task

rate may be 1:0.5, such that every task you allocate to Week 6 reduces the number of tasks

allocated to Week 5 by 0.5. For simplicity, the task rates will always be represented as 1:X,

and you will be fully informed of the value of X when making your decisions.

Week 5 (One Week From Today):

Week 5, one week from today, will occur online and follows week 2 of the experiment. You will

receive an email with instructions on how to access the website with the jobs. You will again

complete your minimum work. You will be asked again to make 5 allocation decisions for each

job. Exactly one of your 20 total allocation decisions will be implemented. That is, we will

implement one decision from Week 4 for Job 1, or one decision from Week 5 for Job 1, or one

decision from Week 4 for Job 2, or one decision from Week 5 for Job 2.

We will discuss how this allocation decision is chosen shortly. We refer to this allocation

20

decision as the ”decision-that-counts.” The tasks you allocated to Week 5 in the decision-

that-counts must be completed. If you do not return or do not complete the tasks in Week 5,

you cannot complete the study, and you will receive only the minimum payment of $10. In order

for your tasks in Week 5 to be counted, they must be submitted by midnight on March 9th, 2012.

Week 6, Two Weeks From Today:

Week 6, two weeks from today, will occur online and follows week 3 of the experiment. You

will receive an email with instructions on how to access the website with the jobs. You will

again complete your minimum work. Then, you must complete the tasks you allocated in the

decision-that-counts. If you do not return or do not complete the tasks in Week 6, you cannot

complete the study, and you will receive only the minimum payment of $10. In order for your

tasks in Week 6 to be counted, they must be submitted by midnight on March 16th, 2012.

Choosing the Decision-That-Counts:

To summarize: In Week 4 (today), you will make 5 allocation decisions for both Job 1 and Job

2 for different task rates. In Week 5, you will also make 5 allocation decisions for both Job 1

and Job 2 for different task rates.

Therefore, you will make 20 total allocation decisions. As stated above, we will choose

only one of these decisions as the decisions-that-counts. That is, we will either implement one

decision from Job 1 or one decision from Job 2, but not both.

The decision-that-counts will be chosen using a similar method to the one used in Week 2.

However, this week, you will make a set of new decisions that affect the precise

way that the decision-that-counts is chosen. To understand these new decisions, please

recall how the decision-that-counts was chosen in Week 2:

How the decision-that-counts was chosen in Week 2

We used 3 steps to choose the decision-that-counts in Week 2.

21

1. First, we chose if the decision-that-counts came from the sooner week (Week 1) or the later

week (Week 2) allocations. To do this, we picked a random number from 1 to 10. If the

number was 1, then the decision-that-counts came from the allocations from the sooner

week (Week 1). If the number is 2,3,4,5,6,7,8,9 or 10, then the decision-that-counts came

from the allocations from the later week (Week 2). Therefore, the decision-that-counts

came from the sooner week with a 10 percent chance and the decision-that-counts came

from the later week with a 90 percent chance. This is the part of the choosing the

decision-that-counts that you will be able to affect in the new set of decisions

this week.

2. Second, we chose if the decision-that-counts came from Job 1 or Job 2. To do this, we

picked a second random number from 1 to 2. If the number was 1 then the decision-that-

counts came from Job 1. If the number was 2, then the decision-that-counts came from

Job 2. Therefore, the decision-that-counts was equally likely to come from Job 1 and Job

2.

3. Third, we chose the decision-that-counts from the 5 allocations you made in the chosen

week and the chosen job. To do this, we picked a third random number from 1 to 5.

Therefore, within the chosen week and chosen job, every allocation was equally likely to

be chosen as the decision-that-counts.

How the decision-that-counts will be chosen in Week 5

In Week 5, the decision that counts will be chosen in a similar way to Week 2 with one

important difference. Today, you will make a set of 15 decisions that can affect the first step

of the process. In Week 2, there was a 10 percent chance that the decision-that-counts

would come from your sooner (Week 1) allocations. In Week 5, based on your decisions, there

will either be a 10 percent chance or a 90 percent chance that decision-that-counts will come

from your sooner (Week 4) allocations. That is, your decisions will change the likelihood that

one of your Week 4 allocations is chosen as the decision-that-counts.

22

For example, in one of the decisions, you will simply be asked to choose which option you

prefer:

1) a 10 percent chance that decision-that-counts will come from your Week 4 allocations

(and 90 percent chance that it comes from Week 5).


(and 10 percent chance that it comes from Week 5)

This decision measures your preference about which choices will be allocated. For example,

if you would prefer that one of your week 5 allocations were chosen rather than a week 4

allocation, you should choose the first option. Please take a second to think about this

decision.

The other decisions measure the strength of your preference about which choices will be

allocated. In these decisions, you will make this same decision but with additional payments

added to one of the two options. So, for example, you will be asked to choose which option

you prefer:


(and 90 percent chance that it comes from Week 5).


(and 10 percent chance that it comes from Week 5) plus $3.

For example, if you would very strongly prefer that one of your Week 5 allocations were

chosen rather than a Week 4 allocation, you might still choose the first option, even though

you could get an extra $3 for choosing the second option. We will choose one of your 15

percentage decisions to be implemented at random. This implemented decision will be used

to determine the percentage chance that the decision-that-counts comes from your Week 4

allocations. Furthermore, if your implemented decision includes an additional payment, this

additional payment will be added to your final $100 completion check.

23

REMEMBER: EACH DECISION COULD BE IMPLEMENTED SO TREAT

EACH DECISION AS IF IT WAS GOING TO BE IMPLEMENTED.

24

Recap:

• You will be continuing in a study that requires participation one day per week on three

consecutive weeks.

• You will receive a completion payment of $100 at the end of the study by check one week

after Week 6. You will return to the xlab on March 23, 2012 to receive this payment.

• If you choose to no longer participate, or do not complete the jobs you chose, you will

receive only a minimum payment of $10 by check one week after Week 6. You will return


• There are two possible jobs in the study. Job 1 is transcription of greek letters. Job 2 is

a tetris game.

• In each week, you will be asked to complete minimum work for each job.

• In Week 4, today, you will be asked to make a series of allocation decisions for both Job

1 and Job 2. You will allocate tasks to Weeks 5 and 6 at various task rates.

• In Week 5, you will again make allocation decisions.

• One of your allocation decisions will be chosen at random as the decision-that-counts and

your allocation will determine the tasks that you complete in Weeks 5 and 6.

• You will be asked to make decisions about the percentage chance that the decision-

that-counts will come from your Week 4 allocations. You will make a series of 15

decisions between (10% Week 4) and (90% Week 4) with additional payments potentially

added to the options. One of these decisions will be implemented. If the decision that

is implemented includes an additional payment, this will be added to your completion

payment.

• One week after Week 6, you will receive your completion payment. You will return to the

xlab on March 23, 2012 to receive this payment.

25

Minimum Work

Now you will complete your minimum work for each job for this week. For each job, we ask

that you complete 10 tasks.

Allocations

Today you will be asked to make a series of 5 allocation decisions for both Job 1 and Job 2. In

these decisions you are asked to allocate tasks between one week from today (Week 5) and two

weeks from today (Week 6).

In each decision you are free to allocate your tasks as you choose. The allocations do not

include the minimum amount of work for each job. You will choose by moving a slider to your

desired allocation.

In the sliders on the screen, you will be asked to make 5 allocations for Job 1. Then, you

will be asked to make 5 allocation decisions for Job. Remember each decision could be the

decision-that-counts, so please make each decision as if it were the one that determines your

tasks.

Determining how the decision-that-counts will be chosen

in Week 5

On the screen you will be asked to choose between a 10% or a 90% chance that the decision-

that-counts comes from today’s allocations (Week 4) rather than the allocations you will make

next week (Week 5). In each decision, you are also given an additional payment for choosing

one of the two options. Remember each decision could be implemented, so please make the

decision as if it was determining the percent chance and your additional payment.

26

F.5 Week 4 Money Instructions

Thank you for completing your allocations. On the following screen we would like to ask you

several additional questions allocating money over time. Your decisions in this portion of the

study are completely unrelated to your allocations over Job 1 and Job 2 and will be paid

separately.

You must be willing to receive your payment for this study by cash provided to you in the

xlab by Professor Ned Augenblick of the Haas School of Business. You will be required to

return to the xlab on the dates indicated to complete the study and so your choice of payments

will not require you to arrive any extra times.

Earning Money

To begin, you will be given a $10 thank-you payment, just for participating in this study! You

will receive this thank-you payment in two equally sized payments of $5 each. The two $5

payments will come to you at two different times. These times will be determined in the way

described below.

In this portion of the study, you will make 5 choices over how to allocate money between

two points in time:

1) March 2nd

2) March 23rd

Note that these are days that you will be in the xlab.

In each decision, you will allocate money between these dates. Once all 5 decisions have

been made, we will randomly select one of the 5 decisions as the decision-that-counts. We will

use the decision-that-counts to determine your actual earnings. Note, since all decisions are

equally likely to be chosen, you should make each decision as if it will be the decision-that-

counts.

When calculating your earnings from the decision-that-counts, we will add to your earnings

the two $5 thank you payments. Thus, you will always get paid at least $5 on March 2st, and

27

at least $5 on March 23nd.

IMPORTANT: All payments you receive will be paid in cash in the xlab. On the

scheduled day of payment, you will come to the xlab for the regular schedule of the study.

Hence, you will not be asked to make any special arrangements to receive payment from this

portion of the study. You will receive your payment from Professor Ned Augenblick.

On your desk are two envelopes: one for the sooner payment and one for the later payment.

Please take the time now to write your participant ID on them and study time/date on them.

28

How It Works:

In the following screen you are asked to make 5 decisions involving payments over time. Each

row is a decision and is numbered from 1 to 5.

Each row will feature a series of options. Each option consists of a sooner payment AND a

later payment. You are asked to pick your favorite option in each row by moving the slider to

your desired location. You should pick the combination of sooner payment AND later payment

that you prefer the most.

Note that there is a trade-off between the sooner payment and the later payment. As the

sooner payment goes down, the later payment goes up. All you have to do for each decision

is choose which combination of sooner and later payment you prefer the most by moving the

slider to that location.

Once all 5 of your decisions are complete, we will choose one at random to be the decision-

that-counts. Your chosen allocation will be implemented.

Consider for example the first decision. If this was chosen as the decision that counts and

your preferred allocation was $11 on March 2st and $10.50 on March 23nd, this would then

be implemented. On March 2st, we would place $11 along with your $5 minimum payment,

making $16.00, into your first envelope. This envelope will be given to you on March 2st in the

xlab. On March 23nd, we would place $10.50 along with your $5 minimum payment, making

$15.50, into your second envelope. This envelope will be given to you on March 23nd when

you return to the xlab. Recall that this will not require you to make any special arrangements

to receive payment as you will be returning to the laboratory as part of the regular schedule

of the study.

Once your payments have been determined, you will write the amounts and dates on the

inside of the two envelopes. When you receive your payments you can guarantee there have

been no clerical errors by checking against the amounts and dates you wrote.

29

Remember that each decision could be the decision-that-counts! It is in your

interest to treat each decision as if it could be the one that determines your pay-

ment.

G Replication Study Instructions

INSTRUCTIONS

Welcome

Thank you for participating in our study. We will begin shortly.

Eligibility and Study RequirementsParticipation in this study will require activities lasting at least 30 minutes on four consec-

utive Thursdays, beginning today and ending three weeks from today: Apr-10, Apr-17, Apr-24,

May-1.

Your first activity for this study is choosing amounts of money to be received one week

from today, Thursday, Apr-17, and two weeks from today Thursday, Apr-24. You will make

nine such choices today and you will make nine such choices one week from today on Thursday,

Apr-17. The choices you make today will be referred to as your Week 1 choices. The choices

you make one week from today on Thursday, Apr-17, will be referred to as your Week 2 choices.

You will make your Week 1 choices today in the laboratory via the study website.

Next week, on Wednesday night, you will receive an email with the study website. This link

will be active at 9am on Thursday morning. You can then login and make your Week 2 choices

using any computer that has internet access. You must make these decisions by 4pm that day.

Your second activity for this study is collecting your chosen payments. Payments will be

collected at a table setup directly outside of the xlab. The Apr-17th payments must be collected

within 2 hours of making your decisions. The Apr-24th payments must be collected between

9am and 6pm.

In order to complete this study you must be willing to both choose amounts of money and

to collect these amounts on Thursday, Apr-17 and Thursday, Apr-24. If you complete these

elements, you will be eligible to receive a completion payment of $30. This can be collected

on Thursday, May-1 outside the xlab between the hours of 9 a.m. and 6 p.m. If you do not

complete all elements of the study, you will be eligible to receive only a payment of $5. This

can also be collected on Thursday, May-1 at the xlab between the hours of 9 a.m. and 6 p.m.

30

If you do not meet or understand the study requirements, please inform us of this now.

Your EarningsAll payments will be made by Professor Ned Augenblick and his assistants. All payments

will be made in cash. You will receive your payments only in designated locations, at

designated times, on designated dates.

Informed ConsentPlaced in front of you is an informed consent form to protect your rights as a subject.

Please read it. If you would like to choose not to participate in the study you are free to leave

at this point. If you have any questions, we can address those now. We will pick up the forms

after the main points of the study are discussed.

AnonymityYour anonymity in this study is assured. Your name will never be recorded or connected

to any decision you make here today. Your email will be collected in order to communicate

with you during the study. After the study, your email information will be destroyed and will

not be connected to your responses in the experiment.

RulesPlease turn your cell phones off. If you have a question at any point, just raise your hand.

Please put away any books, papers, computers, etc.

RegistrationWe will now begin the study. Please open the study interface and enter your e-mail address.

Make sure that you enter a valid e-mail address as this will be the method by which we contact

you throughout the study.

Study ActivitiesWe will now discuss in detail the study activities. In this study there are two activities. The

first activity is choosing payments over time. You will make 9 such choices today, Thursday,

Apr-10. The choices you make today will be referred to as your Week 1 choices. You will make

9 such choices one week from today, Thursday, Apr-17. The choices you make one week from

today will be referred to as your Week 2 choices. In both your Week 1 and Week 2 choices, you

will be choosing an amount of money to be received on Thursday, Apr-17 AND an amount of

money to be received on Thursday, Apr-24.

31

Each choice is a series of options. Each option consists of a sooner payment (to be collected

on Thursday, Apr-17) AND a later payment (to be collected on Thursday, Apr-24). You are

asked to pick your favorite option in each choice by moving a slider to your desired location.

In the example sliders on the website, please explore the potential choices.

Note that there is a trade-off between the sooner payment and the later payment. When

the sooner payment goes down, the later payment goes up and vice versa. In each choice, the

trade-off will be summarized by an “exchange rate,” and will be expressed as a number 1 : X.

This means that if you increase the sooner payment by $1, the later payment will be decreased

by $X. In the example, the exchange rate was 1 : 1, meaning that if you increase the sooner

payment by $1, the later payment is decreased by $1.

Remember, all you have to do for each decision is choose which combination of sooner and

later payment you prefer the most by moving the slider to that location.

The second activity is collecting payments. You will collect the payments from one of

your choices. This means you will collect some amount of money on Thursday, Apr-17

and some amount of money on Thursday, Apr-24. The payment on Apr-17 must be col-

lected within 2 hours of making your decision. The payment on Apr-24 can be collected

anytime between 9am and 6pm. Payments will be collected at a table setup outside of the xlab.

The Experiment TimelineWe will now discuss the timeline of the study. Along the way we will discuss a few

important details of how the study works.

Note: Minimum Payments for Each Week. With the exception of the final completion

payment date, on each day of study participation (including today), you will receive a

minimum payment of $5. These payments are in addition to your chosen payments. This

payment will be paid in cash and be added to your experimental earnings. These payments

must be collected for successful completion of the study.

Week 1(Today: Apr-10)Today you will make 9 choices. Each choice is a series of options. Each option will consist of

a sooner payment (to be collected on Thursday, Apr-17) AND a later payment (to be collected

on Thursday, Apr-24). In each choice, the “exchange rate” will be different.

You will be asked to pick your favorite option in each choice by moving a slider to your

desired location. You should pick the combination of sooner payment AND later payment that

you prefer the most.

Once your 9 choices are complete, you will receive your minimum payment of $5 and depart.

32

Week 2 (One Week From Today: Apr-17)Next week, on Wednesday night, you will receive an email with the study website. This

link will be active at 9am on Thursday morning. You must log in to the study website between

9am and 4pm of next Thursday, Apr-17. You will also receive a reminder email on Thursday.

You will again make 9 choices. Each choice is a series of options. Each option will consist of

a sooner payment (to be collected on Thursday, Apr-17) AND a later payment (to be collected



desired location. You should pick the combination of sooner payment AND later payment that

you prefer the most.

Once your 9 Week 2 choices are complete, you will have made a total of 18 choices: 9 Week

1 choices and 9 Week 2 choices. We will then pick one of your 18 total choices at random

to be the decision-that-counts. Your earnings will be determined by your decision in the

decision-that-counts. You will receive the amounts specified in the decision-that-counts on the

designated dates, Thursday, Apr-17 and Thursday, Apr-24. Recall that these earnings are in

addition to your two $5 minimum payments. Thus, you will always pick up a payment on

Thursday, Apr-17 and $5 on Thursday, Apr-24 of at least $5.

REMEMBER: EACH DECISION COULD BE THE

DECISION-THAT-COUNTS SO TREAT EACH CHOICE AS IF IT WAS THE

ONE DETERMINING YOUR EARNINGS.

Consider if in the decision-that-counts your preferred choice was an $11 sooner payment (to

be collected on Thursday, Apr-17) AND a $10.50 later payment (to be collected on Thursday,

Apr-24). Then, on Thursday, Apr-17 outside the xlab, you would collect $11 along with your $5

minimum payment, making $16.00 in cash. On Thursday, Apr-24 outside the xlab, you would

collect $10.50 along with your $5 minimum payment, making $15.50 in cash.

You must collect your earnings on Apr-17 within two hours of making your decisions online.

You must collect your earnings on Apr-24 between 9am and 6pm.. If you do not collect your

payment on either Thursday, Apr-17 or Thursday, Apr-24, you will be removed from the study

and forfeit all future payments including your completion payment of $30. You will be eligible

only for the reduced payment of $5 at the end of the study. There will be no exceptions to this

rule.

REMEMBER:YOU MUST PICK UP YOUR PAYMENTS BETWEEN 9AM

AND 6PM.

33

YOU MUST PICK UP YOUR PAYMENT NEXT WEEK WITHIN 2 HOURS

OF LOGGING INTO THE WEBSITE.

Week 3, (Two Weeks From Today: Apr-24)In Week 3, you will make no decisions. You will receive an e-mail the night before reminding

you of the study. You must pick up your payment for Thursday, Apr-24 along with your $5

minimum payment outside the xlab between 9am and 6pm. If you do not pick up your payment,

you will be removed from the study and forfeit your completion payment of $30. You will be

eligible only for the reduced payment of $5 at the end of the study. There will be no exceptions

to this rule.

34

Week 4, (Three Weeks From Today: May-1)In Week 4, you will make no decisions. You will receive an email reminding you to pick up

your completion payment outside the xlab between 9am and 6pm on Thursday, May-1. If you

have completed all elements of the study you are eligible to receive a $30 completion payment.

If you have not completed all elements of the study you are eligible to receive a $5 completion

payment.

35

Recap:

• You will be participating in a four week study that requires participation for at least 30minutes on four consecutive Thursdays.

• On Thursday, April-10, Thursday, Apr-17 and Thursday, Apr-24, you will receive mini-mum payments of $5. These minimum payments are in addition to your chosen paymentsfrom the decision-that-counts. These payments must be collected for successful comple-tion of the study.

• In Week 1, today, Thursday, Apr-10, you will be asked to make 9 choices. Each choiceis a series of options. Each option will consist of a sooner payment (to be collected onThursday, Apr-17) AND a later payment (to be collected on Thursday, Apr-24). In eachchoice, the “exchange rate” will be different.

• In Week 2, one week from today, Thursday, Apr-17, you will again be asked to make9 choices. These decisions will be made online between 9am and 4pm. Each choice isa series of options. Each option will consist of a sooner payment (to be collected onThursday, Apr-17) AND a later payment (to be collected on Thursday, Apr-24). In eachchoice, the “exchange rate” will be different.

• You will be asked to pick your favorite option in each choice by moving a slider to yourdesired location. You should pick the combination of sooner payment AND later paymentthat you prefer the most.

• You will make 18 total choices: 9 in Week 1 and 9 in Week 2. We will pick one of your18 total choices at random to be the decision-that-counts.

• Once your Week 2 decisions have been made on Thursday, Apr-17 and the decision-that-counts has been determined, a two hour window will begin. You must collect yourearnings for Thursday, Apr-17 from the decision-that-counts outside of the xlab withinthis two hour window (and between 9 am and 6pm).

• In Week 3, two weeks from today Thursday, Apr-24, you must collect your earnings forThursday, Apr-24 from the decision-that-counts outside the xlab between 9am and 6pm.

• If you fail to collect your earnings from the decision-that-counts you will be removedfrom the study and forfeit all future payments. You will be eligible only for the reducedpayment of $5 at the end of the study.

• In Week 4, three weeks from today Thursday, May-1, you will pick up your completionpayment outside the xlab between the hours of 9 a.m. and 6 p.m. to receive yourcompletion payment. If you have completed all elements of the study you are eligible fora $30 completion payment. If you have not completed all elements of the study you areeligible only for the reduced amount of $5.

36

ConsentNow that we have explained the study, you are free to leave if you would like to choose not to


AllocationsIn the sliders on the screen, you will be asked to make 9 allocations.


if it were the one that determines your payment.

37

INSTRUCTIONS

Welcome:Thank you for participating in our study. We will begin shortly.

Eligibility and Study RequirementsParticipation in this study will require activities lasting at least 30 minutes on four consec-

utive Thursdays, beginning today and ending three weeks from today: Apr-10, Apr-17, Apr-24,

May-1.

Your first activity for this study is choosing amounts of work to be completed one week

from today, Thursday, Apr-17, and two weeks from today Thursday, Apr-24. You will make

nine such choices today and you will make nine such choices one week from today on Thursday,

Apr-17. The choices you make today will be referred to as your Week 1 choices. The choices

you make one week from today on Thursday, Apr-17, will be referred to as your Week 2 choices.

You will make your Week 1 choices today in the laboratory via the study website.

Next week, on Wednesday night, you will receive an email with the study website. This link

will be active at 9am on Thursday morning. You can then login and make your Week 2 choices

using any computer that has internet access. You must make these decisions by 4pm that day.

Your second activity for this study is completing your chosen work. The work in this study

will be completed via the study website and can be completed on any computer that has internet

access. The Apr-17th work must be completed within 2 hours of making your decisions. The

Apr-24th work must be completed between 9am and 6pm.

In order to complete this study you must be willing to both choose amounts of tasks and

to complete these tasks on Thursday, Apr-17 and Thursday, Apr-24. If you complete these

elements, you will be eligible to receive a completion payment of $60. This can be collected

on Thursday, May-1 outside the xlab between the hours of 9 a.m. and 6 p.m. If you do not

complete all elements of the study, you will be eligible to receive only a payment of $5. This

can also be collected on Thursday, May-1 at the xlab between the hours of 9 a.m. and 6 p.m.

If you do not meet or understand the study requirements, please inform us of this now.

Your EarningsThe completion payment will be made by check by Professor Ned Augenblick and his

assistants. You will receive your payment only in designated locations, at designated times, on

designated dates.

38

TasksThe tasks in this study are transcriptions of letters from a greek text. Greek text will

appear in a Transcription Box on your screen. For each letter, you will need to find and select

the corresponding letter and enter it into the Completion Box on your screen. One task is one

row of greek text. For a task to be complete, your accuracy must be 80% or better. Each task

takes an average student between 40-60 seconds.

Informed ConsentPlaced in front of you is an informed consent form to protect your rights as a subject.

Please read it. If you would like to choose not to participate in the study you are free to leave

at this point. If you have any questions, we can address those now. We will pick up the forms

after the main points of the study are discussed.

AnonymityYour anonymity in this study is assured. Your name will never be recorded or connected

to any decision you make here today. Your email will be collected in order to communicate

with you during the study. After the study, your email information will be destroyed and will

not be connected to your responses in the experiment.

RulesPlease turn your cell phones off. If you have a question at any point, just raise your hand.

Please put away any books, papers, computers, etc.

RegistrationWe will now begin the study. Please open the study interface and enter your e-mail address.

Make sure that you enter a valid e-mail address as this will be the method by which we contact

you throughout the study.

39

Study ActivitiesWe will now discuss in detail the study activities. In this study there are two activities.

The first activity is choosing amounts of work over time. You will make 9 such choices today,

Thursday, Apr-10. The choices you make today will be referred to as your Week 1 choices. You

will make 9 such choices one week from today, Thursday, Apr-17. The choices you make one

week from today will be referred to as your Week 2 choices. In both your Week 1 and Week 2

choices, you will be choosing an amount of work to be completed on Thursday, Apr-17 AND

an amount of work to be completed on Thursday, Apr-24. The amount of work on each date is

expressed as a number of tasks.

Each choice is a series of options. Each option consists of a sooner number of tasks (to be

completed on Thursday, Apr-17) AND a later number of tasks (to be completed on Thursday,

Apr-24). You are asked to pick your favorite option in each choice by moving a slider to your

desired location. In the example sliders on the website, please explore the potential choices.

Note that there is a trade-off between the sooner number of tasks and the later number of

tasks. When the sooner number of tasks goes down, the later number of tasks goes up and

vice versa. In each choice, the trade-off will be summarized by an “exchange rate,” and will be

expressed as a number 1 : X. This means that if you increase the sooner number of tasks by

1 task, the later number of tasks will be decreased by X tasks. In the example, the exchange

rate was 1 : 1, meaning that if you increase the sooner number of tasks by 1, the later number

of tasks is decreased by 1.

Remember, all you have to do for each decision is choose which combination of sooner and

later tasks you prefer the most by moving the slider to that location.

The second activity is completing work. This means you will complete some tasks on

Thursday, Apr-17 and some tasks on Thursday, Apr-24. The tasks on Apr-17 must be

completed within 2 hours of making your decision. The tasks on Apr-24 can be completed

anytime between 9am and 6pm. Tasks will be completed online using any computer that has

access to the Internet.

The Experiment TimelineWe will now discuss the timeline of the study. Along the way we will discuss a few

important details of how the study works.

Note: Minimum Work for Each Week. With the exception of the final completion payment

date, on each day of study participation (including today), you are required to complete a

minimum number of 10 tasks. These tasks are in addition to your chosen numbers of tasks.

These tasks must be completed for successful completion of the study.

40

Week 1(Today: Apr-10)Today you will make 9 choices. Each choice is a series of options. Each option will consist of

a sooner number of tasks (to be completed on Thursday, Apr-17) AND a later number of tasks

(to be completed on Thursday, Apr-24). In each choice, the “exchange rate” will be different.


desired location. You should pick the combination of sooner tasks AND later tasks that you

prefer the most.

Today you will complete your minimum work of 10 tasks, then make your 9 choices, and

depart.

Week 2 (One Week From Today Apr-17)Next week, on Wednesday night, you will receive an email with the study website. This

link will be active at 9am on Thursday morning. You must log in to the study website between

9am and 4pm of next Thursday, Apr-17. You will also receive a reminder email on Thursday.

You will again complete minimum work of 10 tasks. Then, you will again make your 9

choices. Each choice is a series of options. Each option will consist of a sooner number of

tasks (to be completed on Thursday, Apr-17) AND a later number of tasks (to be completed



desired location. You should pick the combination of sooner tasks AND later tasks that you

prefer the most.

Once your 9 Week 2 choices are complete, you will have made a total of 18 choices: 9 Week

1 choices and 9 Week 2 choices. We will then pick one of your 18 total choices at random to

be the decision-that-counts. Your tasks will be determined by your decision in the decision-

that-counts. You will complete the tasks specified in the decision-that-counts on the designated

dates, Thursday, Apr-17 and Thursday, Apr-24. Recall that these tasks are in addition to your

10 tasks of minimum work. Thus, you will always login into the website and complete at least

10 tasks on Thursday, Apr-17 and 10 tasks on Thursday, Apr-24.

REMEMBER: EACH CHOICE COULD BE THE DECISION-THAT-COUNTS

SO TREAT EACH CHOICE AS IF IT WAS THE ONE DETERMINING YOUR

TASKS.

Consider if in the decision-that-counts your preferred choice was 30 sooner tasks (to be

completed on Thursday, Apr-17) AND 25 later tasks (to be completed on Thursday, Apr-24).

Then, on the study website, on Thursday, Apr-17, you would complete 30 tasks along with

41

your 10 tasks of minimum work, making 40 tasks. On Thursday, Apr-24, on the study website,

you would complete 25 tasks along with your 10 tasks of minimum work, making 35 tasks.

You must complete your tasks on Apr-17 within two hours of making your decisions online.

You must complete your tasks on Apr-24 between 9am and 6pm. If you do not complete your

tasks on either Thursday, Apr-17 or Thursday, Apr-24, you will be removed from the study and

forfeit the completion payment of $60. You will be eligible only for the reduced payment of $5

at the end of the study. There will be no exceptions to this rule.

REMEMBER:YOU MUST COMPLETE YOUR TASKS BETWEEN 9AM AND

6PM.

YOU MUST COMPLETE YOUR TASKS NEXT WEEK WITHIN 2 HOURS

OF LOGGING INTO THE WEBSITE.

Week 3, (Two Weeks From Today: Apr-24)In Week 3, you will make no decisions. You will receive an e-mail the night before

reminding you of the study. You must login into the website between 9am and 6pm and you

must complete your tasks from the decision-that-counts for Thursday, Apr-24 along with your

10 tasks of minimum work on the study website. If you do not complete your tasks by 6pm,

you will be removed from the study and forfeit your completion payment of $60. You will be

eligible only for the reduced payment of $5 at the end of the study. There will be no exceptions

to this rule.

Week 4, (Three Weeks From Today: May-1)In Week 4, you will make no decisions. You will receive an email reminding you to pick up

your completion payment in the xlab. If you have completed all elements of the study you are

eligible to receive a $60 completion payment. If you have not completed all elements of the

study you are eligible to receive a $5 completion payment. These payments will be available

outside of the xlab on Thursday, May-1 between the hours of 9 a.m and 6 p.m.

42

Recap:

• You will be participating in a four week study that requires participation for at least 30minutes on four consecutive Thursdays.

• On Thursday, April-10, Thursday, Apr-17 and Thursday, Apr-24, you are required tocomplete minimum work of 10 tasks. These tasks are in addition to your chosen tasksfrom the decision-that-counts. These tasks must be completed for successful completionof the study.

• In Week 1, today Thursday, Apr-10, you will be asked to make 9 choices. Each choice is aseries of options. Each option will consist of a sooner number of tasks (to be completed onThursday, Apr-17) AND a later number of tasks (to be completed on Thursday, Apr-24).In each choice, the “exchange rate” will be different.

• In Week 2, one week from today Thursday, Apr-17, you will again be asked to make 9choices. Each choice is a series of options. Each option will consist of a sooner numberof tasks (to be completed on Thursday, Apr-17) AND a later number of tasks (to becompleted on Thursday, Apr-24). In each choice, the “exchange rate” will be different.

• You will be asked to pick your favorite option in each choice by moving a slider to yourdesired location. You should pick the combination of sooner tasks AND later tasks thatyou prefer the most.

• You will make 18 total choices: 9 in Week 1 and 9 in Week 2. We will pick one of your18 total choices at random to be the decision-that-counts.

• Once your Week 2 decisions have been made on Thursday, Apr-17 and the decision-that-counts has been determined, a two hour window will begin. You must complete your tasksfor Thursday, Apr-17 from the decision-that-counts on the study website within this twohour window (and between 9 am and 6pm).

• In Week 3, two weeks from today Thursday, Apr-24, you will again login to the website.You must complete your tasks for Thursday, Apr-24 from the decision-that-counts on thestudy website within two hours of logging in (and between 9am and 6pm).

• If you fail to complete your tasks from the decision-that-counts you will be removed fromthe study. You will be eligible only for the reduced payment of $5 at the end of the study.

• In Week 4, three weeks from today Thursday, May-1, you will come outside the xlabbetween the hours of 9 a.m. and 6 p.m. to receive your completion payment. If you havecompleted all elements of the study you are eligible for a $60 completion payment. If youhave not completed all elements of the study you are eligible only for the reduced amountof $5.

43

ConsentNow that we have explained the study, you are free to leave if you would like to choose not to


Minimum WorkRecall that, each week, you must complete a mandatory number of 10 tasks. We will not

complete those tasks.

AllocationsIn the sliders on the screen, you will be asked to make 9 allocations.


if it were the one that determines your payment.

44

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