Operant Experimental Strategies

Cultural Experimental Strategies

Hold deprivation constant and manipulate reinforcement contingency (SR+ - Ext - SR+ - Ext)

Hold antecedent conditions for cultural unit constant and manipulate metacontingencies

Hold reinforcement contingency constant and manipulate deprivation levels (Hi dep – low dep – hi dep – low dep)

In this study, metacontingencies were held constant and antecedent conditions for IBCs were manipulated

Manipulating Antecedents

• Independent variable: Availability of survival resources was the antecedent condition manipulated - 2 values = “rich” and “poor” - represented by proportion of

hunts that each player comes home with no rabbits in a condition

• Dependent variable: “Dyadic fitness” - measured by the proportion of trials in a condition that both

players can hunt on the next trial- A player cannot hunt if she has no rabbits to eat- In both conditions there is an equal number of times that a

player must give a rabbit to another player or they will both be unable to hunt and will lose all stored resources

Rich

Poor

Independent Variable: Resource Availability

Measure: Frequency of coming home empty handed

Values

14 trials out of 60

22 trials out of 60

Experimental Session

• Each dyad participated in a single session of about 2 hours

• 6 conditions were run in the session (generally 3 Rich and 3 Poor)

• Conditions ran either 60 (Experiment I) or 100 (Experiment II) trials

• Participants were paid at the end of the session• Participants were not allowed to talk during the

session

“Hunting trial” initiated by pressing “hunt” key.

For you both to go hunting, one of you presses this key marked “HUNT””.

Trial StructureTrial Structure

Each player brings her own rabbits home from the hunt

P 1P 2

Then you each have to decide what you will do with your own rabbits.

Trial StructureTrial Structure

• With any remaining rabbits, players may:- Store a rabbit for future use (one more trial)- Trade a rabbit for another commodity (money)- Give a rabbit to the other player

Trial StructureTrial Structure

• First, in order to proceed to the next trial, a player must have a rabbit to eat

• If one player can’t hunt, the other can continue but will eventually fail to have a rabbit to eat

• Number of trials both can hunt during a condition is measure of “dyadic fitness”

Dyadic Fitness (AP) per Condition%

Dya

dic

Fitn

ess

(AP)

Conditions (60 trials)

Rich (0.23)Poor (0.36)

Rich

Poor

Independent Variable: Environmental Scarcity

Frequency of coming home empty handed

Values

16 trials out of 100

46 trials out of 100

14 trials out of 60

22 trials out of 60

Dyadic Fitness (AP) per Condition%

Dya

dic

Fitn

ess

(AP)

Conditions (100 trials)

Conditions (60 trials)

Rich (0.23)Poor (0.36)