Social Projection and a Quantum Approach for Behavior in Prisoner's Dilemma

In their target article, “Social Projection Can Solve Social Dilemmas,” Krueger, DiDonato, and Freestone (KDF, this issue) provide a detailed and thoughtprovoking critique of existing approaches to understanding human behavior in social dilemmas, including the famous Prisoner’s Dilemma paradigm. In this way, they motivate their own approach, based on the idea of social projection. This commentary establishes some theoretical relations between the social projection hypothesis and a new “quantum inspired” model of behavior for the prisoner’s dilemma game (Pothos & Busemeyer, 2009). Our discussion reveals a subtle difference in the motivation between the social projection hypothesis and the “quantum inspired” model, a commonality of assumptions (despite the obviously different form of the models), and a complementarity of objectives (and strengths). Further elaboration of the two models may well lead to a convergence between them, which will further enhance our insight of both the factors that drive human intuition in social dilemmas and the relevant formal principles. One of the most famous paradigms for studying social dilemmas and human cooperative behavior is Prisoner’s Dilemma (PD), in which a player can decide to cooperate (C) or defect (D) with another (imaginary or otherwise) player, who can also C or D. A payoff matrix determines the reward of the player depending on her choice and on the actions of the other player. The payoff matrix is typically set up in such a way that if both players C they receive a relatively high amount (say, $20) and if they both D a relatively low amount (say, $10). But if the first player chooses to D and the second chooses to C, then the first player receives the highest possible reward ($25) and the second player the lowest possible reward ($5, and vice versa). Perhaps the PD paradigm has attracted the attention it has because it embodies one of the fundamental riddles of why human societies work: Mutual cooperation leads to success (prosperity) for all members, but individuals who choose to D stand to gain the most (as long as the majority C). A classical rationality view simply predicts that each player should D (the Nash equilibrium is for both players to D). In fact, in laboratory versions of the PD task, naive observers often choose to C and so ignore the prescription from classical (selfish) rationality. Understanding the psychological mechanism that makes a C decision more favorable has proved a major theoretical challenge and is the focus of the target article by KDF. KDF provide a detailed overview of alternative theories to account for cooperative behavior in social dilemmas, such as PD. For example, they discuss a morality theory, according to which cooperation is favored because it is considered a more just or fair strategy. A reciprocity theory involves assumptions regarding expectations of how the other player ought to behave. A benevolence (social values) hypothesis computes expected reward for a player as a weighted sum of the player reward and the reward of the other player. Team reasoning approaches consider reward from the point of view of the entire team, not just the individual players. An error approach assumes that the optimal strategy is indeed to D; however, players simply occasionally make errors. Yet another explanation for cooperative behavior has to do with observations (or assumptions) regarding the preponderance of CC situations (i.e., situations in which both players decide to C) in particular types of games. KDF’s critical evaluation of these approaches reveals several weaknesses and so motivates their own explanation. This depends on social projection, that is, the idea that naive observers often believe that others will behave as they do. Social projection allows a naive observer to calculate an estimate of expected gain for cooperating, under particular assumptions of