Prisoner’s Dilemma Game with an External Selecting Agent: A Metacontingency Experiment 1

4 participants, can’t see each other, each facing a computer Each player presses either X or Y on each trial Amount of money a press earns depends on whether X or Y is chosen and on what the other players press Value of pressing X and Y depends on all players’ responses on that trial The more players press X - by giving up immediate advantage of Y -, the higher the global gain Each choice is immediately seen by every player. When each player has made a choice everyone receives feedback on how much he’s gained and on how much everybody else has gained Each choice can be seen as an S D for the next one Daniele Ortu, Tomas Woelz & Sigrid Glenn

Points Earned Aggregate Product = YYYY (28) = XYYY (35) = XXYY (46) = XXXY (55) = XXXX (64)

Results of Previous Research Usually, with 2 players, they learn the advantages of pressing X and get into a stable pattern of X presses But as the number of players increases, pressing X generally decreases and stable patterns are unlikely 2

Experimental Design We added an external selecting agent to function as the independent variable in an A-B-A-B design We call the action of the external agent “feedback from the market” The players receive on a VR2 schedule feedback showing how the market is reacting to the product The experimenter decides a maximum gain/loss possible per trial per player, e.g. 10cents (market feedback magnitude) In each condition all four players have to pick the required key to have any gains from market

Condition A : Press X The market feedback is contingent on how many players press X The greater the number of players who press X in the period since last feedback, the more the market pays The more the market pays, the more money the company and the players gain (company money is equally shared) Condition is changed when criterion is reached - 8 consecutive trials of XXXX - or after 15 minutes if criterion is not reached

Points Earned Aggregate Product Cultural Consequence = YYYY (28) = XYYY (35) = XXYY (46) = XXXY (55) = XXXX (64) 10 Condition A: Press X

Condition B : Press Y The market feedback is contingent on how many players press Y The greater the number of players who press Y in the period since last feedback, the more the market pays The more the market pays, the more money the company and the players gain (company money is equally shared) Condition is changed when criterion is reached - 8 consecutive trials of YYYY - or after 15 minutes if criterion is not reached

Points Earned Aggregate Product Cultural Consequence = YYYY (28) = XYYY (35) = XXYY (46) = XXXY (55) = XXXX (64) -10 Condition B: Press Y

Independent Variables Number of X presses in X condition Number of Y presses in Y condition Coordination across time among players, in pressing X or Y (can’t be measured by looking at individual data) Dependent Variables Market delivering positive consequences for all players pressing X or pressing Y Magnitude of Market’s Feedback

X 25 INCREASE 70 X 10 X 10 X 25 X 25X FADE OUT NO X 25 INCREASE 70 X 10 X 10 X 25 X 25X FADE OUT NO x y X Y x y X Y NO x y X Y x y X Y NO EARNINGSEARNINGS P1 P2 P3 P4 $ MARKET M A R K E T F E E D B A C K M A G N I T U D E INCREASE FADE OUT NO MARKET X Y X Y X Y X Y Y FADE OUT NO Conditions

X 25 INCREASE 70 X 10 X 10 X 25 X 25X FADE OUT NO x y X Y x y X Y NO EARNINGSEARNINGS P1 P2 P3 P4 $ MARKET M A R K E T F E E D B A C K M A G N I T U D E INCREASE FADE OUT NO MARKET X Y X Y X Y X Y Y FADE OUT NO Operant Culturant Conditions

References 1Ortu, D., Woelz, T., & Glenn, S. S. Prisoner’s Dilemma Game with an External Selecting Agent: A Metacontingency Experiment (2008) Paper presented at Association for Behavior Analysis Convention, Chicago, IL 2Yi & Rachlin, 2004