Association for Behavior Analysis International

The Experimental Analysis of Human Behavior Special Interest Group is honored to recognize Dr. Howard Rachlin. Dr. Rachlins pioneering research on intertemporal choice has integrated behavior analysis, experimental economics, and judgment and decision making. His research on delay discounting has informed translational research assessing the role discounting plays in the etiology of impulse control disorders such as substance abuse, gambling, and other addictions. Recently, Dr. Rachlin has extended his research program into social domains. The focus of Dr. Rachlins address will be on the effects of real versus hypothetical outcomes on choice in an iterated Prisoners Dilemma game and on altruistic behavior in a social discounting task. Dr. Rachlin is joined in this symposium by colleagues who have been inspired by him and his work. Dr. Matthew L. Locey will present research on the role of temporal discounting and magnitude of social benefit on behavior in a Prisoners Dilemma game. Dr. Leonard Green will present a paper, co-authored with Dr. Joel Myerson, discussing the relationship between delay and probability discounting of real and hypothetical outcomes. Dr. Eric A. Jacobs will serve as discussant for the session and will present the award. Please join us in celebrating the many achievements of Dr. Howard Rachlin.

In a Prisoner's Dilemma Game (PDG), cooperation benefits the group but is costly to the individual (relative to defection). On the surface, these contingencies appear to favor defection over cooperation. A deeper analysis that considers delay and social discounting might help to explain why anyone might choose to cooperate in such a context. In Experiment 1 participants played a PDG against a computer with perfect reciprocation (tit-for-tat). The tit-for-tat contingency could potentially reinforce the participants cooperation (by computer-cooperation) and punish the participants defection (by computer-defection). The delay from participant-choice to computer-choice was manipulated. Consistent with delay discounting, more cooperation was found with shorter delays than with longer delays. Experiment 2 opposed the personal benefit from defection to the socially discounted benefit to others from cooperation. In Phase 1 the social benefit of cooperating was varied by the number of other players. In Phase 2 the social benefit of cooperating was varied by the amount of money earned by the other player. In both phases, more participants cooperated when the social benefit of doing so was high than when it was low.

Laboratory studies of choice and decision making among real monetary rewards typically use smaller real rewards than those common in real life. When laboratory rewards are large, they are almost always hypothetical. In applying laboratory results meaningfully to real-life situations, it is important to know the extent to which choices among hypothetical rewards correspond to choices among real rewards and whether variation of the magnitude of hypothetical rewards affects behavior in meaningful ways. The present study compared real and hypothetical monetary rewards in two experiments. In Experiment 1, participants played a temporal discounting game that incorporates the logic of a repeated prisoners-dilemma (PD) type game versus tit-for-tat; choice of one alternative (defection in PD terminology) resulted in a small-immediate reward; choice of the other alternative (cooperation in PD terminology) resulted in a larger reward delayed until the following trial. The larger-delayed reward was greater for half of the groups than for the other half. Rewards also differed in type across groups: multiples of real nickels, hypothetical nickels or hypothetical hundred-dollar bills. All groups significantly increased choice of the larger delayed reward over the 40 trials of the experiment. Over the last 10 trials, cooperation was significantly higher when the difference between larger and smaller hypothetical rewards was greater. Reward type (real or hypothetical) made no significant difference in cooperation. In Experiment 2, real and hypothetical rewards were compared in social discounting the decrease in value to the giver of a reward as social distance increases to the receiver of the reward. Social discount rates were well described by a hyperbolic function. Discounting rates for real and hypothetical rewards did not significantly differ. These results add to the evidence that results of experiments with hypothetical rewards validly apply in everyday life.