Temporal Spacing of Learning:Can It Help Reduce Forgetting?

Hal Pashler

University of California, San Diego

Dept of Psychology

Douglas Rohrer, USFJohn Wixted, UCSD

Nicholas Cepeda, UCSD & Univ of Colorado

Shana Carpenter, UCSD

Michael Mozer, Univ of Colorado Computer Science Dept.

Ed Vul, MIT

Power Function

Days

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Pro

po

rtio

n C

orr

ect

0.0

0.2

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1.0

Study-Test

Study-Study

0.92(.04t + 1)-1.63

0.87(.04t + 1)-1.58

Forgetting: A Classic Topic in Experimental Psychology

Forgetting in K-12 Education

• Educational failure may often reflect forgetting as well asabsence of initial mastery.

• Summer Vacation Set-backs

• “Regression” to partial understanding and initial misunderstandings (Bob Siegler).

“People who went to college can tell you what they learned in just 5 minutes. So, at my college, students learn just the same stuff – all in 5 minutes.”

Father Guido Sarducci’s

5-Minute College

Our Research Aim:

Identify procedures that

• can readily be applied in educational contexts.

• reduce rate of forgetting

2. Temporal Distribution of Study Sessions

4. Form and Timing of Feedback

1. Temporal Distribution of Practice within Study Sessions

3. Overlearning

Topics

5. Testing Effects

Analyzing Temporal Distribution of Study Sessions

Time

StudySomething

Once

StudyIt

AgainTest

Inter-study Interval (ISI)

Retention Interval (RI)

• Scarcely any application in classroom or instructional technology

• Huge Literature showing poor learning with very short ISI (“spacing effect”)

Why no practical translation

if the literature is so huge?

425 papers

Spacing Research with Significant Retention Intervals (> 1 day)

14 papers

(Many with serious methodological problems)

0

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-1 0 1 2 3 4 5 6 7 8

Inter-Study Interval (days)

Pe

rce

nt

Co

rre

ct

Re

ca

llAusubel (1966)

Childers & Tomasello (2002)

Childers & Tomasello (2002)

Edwards (1917)

Edwards (1917)

Glenberg & Lehmann (1980)

RI = 6 days

RI = 7 days

RI = 3 days

RI = 4 days

RI = 1 day

RI = 7 days

10-day Retention Interval Study

Jani? Horse

Interstudy Interval = 0, 1, 2, 4, 7, 14 days

TasksSwahili-English Vocabulary

Session 1: Study to Criterion[0,1,2,4,7, or 14 days]

Session 2: Fixed amount of further study[10 day RI]

Session 3: Test

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-7 0 7 14 21 28 35 42 49 56 63 70 77 84 91

Inter-Study Interval (days)

Per

cen

t C

orr

ect

Rec

all Vocabulary

FactsPictures

Facts

Objects

10-day RI

Data from 182 subjects tested for 3 sessions

6-Month Retention Interval

? Coccolith.

Interstudy Interval = 0, 1, 7, 28, 84, or 168 days

Tasks1. Learn names of little-known objects

2. Learn little-known facts

Who invented snow golf? Rudyard Kipling.

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-7 0 7 14 21 28 35 42 49 56 63 70 77 84 91

Inter-Study Interval (days)

Per

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all Vocabulary

FactsPictures

6-month RI: Facts

Swahili10-day RI

6-month RI: Object Names

Data from 161 subjects tested for 3 sessions

0

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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

ISI/RI Ratio

Per

cent

Cor

rect

Rec

all

VocabularyFactsPictures

Optimum ISI = 10 – 20% of retention interval?

Let’s Plot Performance as a Function of ISI/RI Ratio

Larger Experiment now in Progress

RI = {7, 35, 70, or 350 days}

ISI = {0, 7, 14, 21, or 105 days}

X

• Web-based Learning of Facts

• Session 1: Train to Criterion

• Session 2: 2 Test/Study Repetitions

• Test: Recall, then 5-Alternative Recognition

Recall Data (n ~ 2,000 subjects)

7 days RI

35 days RI

70 days RI

350 days RI

Recognition Data (n ~ 2,000 subjects)7 days RI35 days RI

70 days RI

350 days RI

• Large effects of spacing generalize to learning novel mathematical problem-solving skill (combinatorics) [USF]

Generalizing Beyond Fact & Vocabulary Learning

• Pattern-recognition skills may not show similar spacing effects [www.learnmelanoma.org]

Empirical Conclusions

• Using ISI of about 10-20% of retention interval seem to optimize memory over a wide time range

• Too short an ISI is much worse than too long

• Using appropriate inter-study interval can produce 100% - 200% improvement in ultimate

memory

• To determine optimum spacing, you need to know how long you want the learner to retain the information.

• For most educational goals, 6-mo. delayed reviews likely to be very cost-effective (Preuss School Study)

• Cumulative finals probably have huge effect on what students retain over years.

Tentative Practical Implications