Are irrational reactions to unfairness truly emotionally-driven? Dissociated behavioural and emotional responses in the Ultimatum Game task

Abstract

The “irrational” rejections of unfair offers by people playing the Ultimatum Game (UG), a widely used laboratory model of economical decision-making, have traditionally been associated with negative emotions, such as frustration, elicited by unfairness (Sanfey et al., 2003, van’t Wout et al., 2006). We recorded skin conductance responses as a measure of emotional activation while participants performed a modified version of the UG, in which they were asked to play both for themselves and on behalf of a third-party. Our findings show that even unfair offers are rejected when participants’ payoff is not affected (third-party condition); however, they show an increase in the emotional activation specifically when they are rejecting offers directed towards themselves (myself condition). These results suggest that theories emphasizing negative emotions as the critical factor of “irrational” rejections (Pillutla & Murninghan, 1996) should be re-discussed. Psychological mechanisms other than emotions might be better candidates for explaining this behaviour.

Introduction

In recent years the study of the role of emotions in decision-making has become an increasingly prominent issue in cognitive neuroscience. A wealth of studies have hypothesized an emotional pathway in the brain that seems to operate in many types of decisional processes, including moral judgment (Moll, Zahn, de Oliveira-Souza, Krueger, & Grafman, 2005, for a review) and economical decision-making (Pillutla and Murninghan, 1996, Sanfey et al., 2003), that have traditionally been linked to rational thinking and choices (Kohlberg, 1969, von Neumann and Morgestern, 1947).

The Ultimatum Game (UG), a model of economical decision-making employed in the laboratory, has always been thought of as a classical example of emotionally-driven behaviour. In this task, one player (the proposer) makes offers to a second player (the responder) of how to split an amount of money given by the experimenter; the responder, in turn, can either accept or reject the offers. If the responder accepts, the money will be divided as the proposer has decided, otherwise both players will receive nothing. Classical economical theories posit that, to maximize his/her own gain, the proposer should always offer the smallest amount of money, whilst the responder, following the principle that “few is better than nothing”, should accept every offer. However, the behavioural findings clearly show that the proposer typically divides the money equally, and that the responder rejects offers which favor the proposer too much, and those that he/she considers unfair (Bolton & Zwick, 1995). Importantly, this behavioural pattern has also been observed in both the single-shot UG, in which the two players interact only once, and in the covered UG, in which the proposer is not informed about the responder’s reaction (Abbink et al., 1999, Zamir, 2001), both of which are paradigms where rejections lose their role as negotiating tools.

Individuals’ “irrational” choices have been explained in terms of altruistic punishment (Fehr & Gachter, 2002). According to this theory, the punishment, even if costly and yielding no direct benefit for the punisher (as in the case of single-shot UG), is used to penalize selfish behaviour of others, as it leads them to cooperate in future interactions (Fehr & Gachter, 2002). It has been suggested that irrational rejections might be best explained by negative emotions, such as frustration, that drive participants to punish rather than making an utilitarian choice (Fehr and Gachter, 2002, Pillutla and Murninghan, 1996). Consistent with this view, Sanfey et al. (2003) have recently associated the rejection of unfair offers with an increase of both the neural activity in anterior insula, traditionally correlated with feelings of anger and disgust (Calder et al., 2001, Phillips et al., 1997), and the skin conductance response (van’t Wout et al., 2006), a measure of emotional activation (Bouscein, 1992).

It has also been argued that only self-centered emotions, for instance anger and frustration, play some role in the UG, as individual payoff is heavily involved in this task (Moll & de Oliveira-Souza, 2007). However, it has also been proved that individuals choose an act of punishment even though their payoffs are not directly affected by a violation of fairness and cooperation norms (i.e. the third-party punishment). Fehr and Fischbacher (2004), for instance, found that participants decided to give up some of their own money to punish the unfair behaviour of one player towards another. Thus, altruistic punishment also occurs in conditions in which unfairness should not elicit, at least in principle, any self-centered emotion. This raises the question of whether, in the UG task, the “irrational” punishing behaviour and negative emotions are always causally related, or whether they can operate separately depending on the myself/third-party distinction.

In the present study, we investigated the role of emotions in the UG by measuring skin conductance responses (SCR) while participants played as responders in a modified version of the UG and by collecting emotional ratings after they completed the task to measure the valence of the hypothetical arousal. Participants carried out both the classical version of the UG and a modified version of the task in which any putative monetary income was not going into the participants’ own pocket, but into a third-party’s (see Section 2). Indeed, in the latter condition the proposer’s offer did not directly address the participant’s payoff, unfairness should in principle, elicit neither self-centered emotions (Moll & de Oliveira-Souza, 2007), nor, as consequence, SCR increases when the offer is about to be rejected (van’t Wout et al., 2006). Thus, the account according to which the punishing behaviour and the negative emotions are causally related (Fehr and Gachter, 2002, Pillutla and Murninghan, 1996), also predicts that such emotional decrease should be associated with a similar decrease in the amount of punishing choices (rejections) (van’t Wout et al., 2006). However, based on previous studies of altruistic punishment (e.g. Fehr & Fischbacher, 2004), we predicted that participants should reject unfair offers addressing a third-party; if this were indeed the case, we expected a significant increase in SCR for offers about to be rejected even in the third-party condition as well.