Original Article
Anticipated verbal feedback induces altruistic behavior

https://doi.org/10.1016/j.evolhumbehav.2007.11.001Get rights and content

Abstract

A distinctive feature of humans compared to other species is the high rate of cooperation with nonkin. One explanation is that humans are motivated by concerns for praise and blame. In this paper we experimentally investigate the impact of anticipated verbal feedback on altruistic behavior. We study pairwise interactions in which one subject, the “divider,” decides how to split a sum of money between herself and a recipient. Thereafter, the recipient can send an unrestricted anonymous message to the divider. The subjects' relationship is anonymous and one-shot to rule out any repeated interaction effects. Compared to a control treatment without feedback messages, donations increase substantially when recipients can communicate. With verbal feedback, the fraction of zero donations decreases from about 40% to about 20%, and there is a corresponding increase in the fraction of equal splits from about 30% to about 50%. Recipients who receive no money almost always express disapproval of the divider, sometimes strongly and in foul language. Following an equal split, almost all recipients praise the divider. The results suggest that anticipated verbal rewards and punishments play a role in promoting altruistic behavior among humans.

Introduction

Human altruism is considered an evolutionary puzzle (Nowak, 2006).1 While repeated interaction and reputation formation can explain altruistic behavior in small closely knit groups, altruism is often considerable among strangers who interact only once. Here, we investigate the hypothesis that altruism is caused by feelings of shame and pride and that these feelings are accentuated by others' verbal evaluation.

Our evidence comes from a dictator game experiment with recipient feedback. We find that the opportunity for verbal feedback substantially increases donations compared to a control treatment without any feedback.

In a typical dictator game, one person (the divider) is in charge of dividing a resource between herself and another person (the recipient). Usually, the resource is an amount of money, and the divider is free to choose any division. While nothing prevents the divider from taking all the money, a substantial fraction of the dividers leaves some money to the recipient. In laboratory experiments in Western cultures, the equal split is the second most common allocation, with the average donation typically falling in the interval 10–30% (Camerer, 2003). Henrich et al. (2004) report similar results from subject pools that are isolated from Western culture.

The (equal) sharing norm is widespread, and there are several reasons for thinking that generosity in dictator games is driven by a desire for social esteem in relation to this norm. When the divider's choice is observable to the experimenter (Hoffman, McCabe, Shachat, & Smith, 1994) and to the recipient (Andreoni and Bernheim, 2007, Dana et al., 2006 ), the division becomes more generous. Even pictures of eyes, subtly triggering a sense of being watched, has a significant positive impact on generosity in both laboratory experiments (Haley & Fessler, 2005) and field settings (Bateson, Nettle & Roberts, 2006). This evidence is congruent with the long-standing view that prosocial behavior is fuelled by the desire to feel justified pride and to avoid feeling shame (Cooley, 1922, Scheff, 1988, Smith, 1790), and more generally with the desire to signal favorable characteristics (Bliege Bird and Smith, 2005, Henrich and Gil-White, 2001). Importantly, these are quite tight associations. Andreoni and Bernheim (2007) formally demonstrate that a signaling model based on an equal sharing norm predicts the observed spikes in dictator game data [see also Ellingsen and Johannesson (in press) and the references therein].

Our preferred interpretation of the result that anticipated verbal feedback matters for behavior is that feelings of shame and pride in connection to norm compliance are accentuated by emotional communication. Knowing that someone is justifiably angry does not arouse the same level of shame as facing the angry person, or even having to read angry messages. The hypothesis that people are motivated by a desire for praise is not new. It can be tracked back at least to Thomas Hobbes (1651, Chapter XI), who wrote: “Desire of praise disposeth to laudable action, such as pleaseth them whose judgment they value.”2 In the paper's final section we discuss evolutionary foundations for Hobbes's hypothesis in light of recent theories and evidence.

Although the applied psychology literature has long been finding significant effects of symbolic rewards in the workplace and in schools (Henderlong and Lepper, 2002, Stajkovic and Luthans, 2003), such studies suffer from the problem that symbolic rewards may be closely correlated with subsequent material rewards. A similar objection may be directed at the few experimental studies that consider symbolic punishment in repeated public goods games (Gächter and Fehr, 1999, Masclet et al., 2003, Noussair and Tucker, 2005). While behavior does tend to become more prosocial when communication is possible, it is difficult to know whether behavior changes in order to reduce the suffering generated directly by the verbal sanction or to mitigate the effect that verbal messages have on future material payoffs. Relatedly, the fact that people are generally more cooperative when they are allowed to interact face to face or merely to see their opponents, as documented by Ostrom and Walker, 1997, Bohnet and Frey, 1999 respectively, could in principle be due either to increased empathy or to reputational effects. Together with Xiao and Houser (2007) (to be discussed below) ours is the first study to isolate the impact of anticipated feedback on altruistic behavior.

Section snippets

Experimental design and procedures

We conducted a one-shot anonymous dictator game experiment with and without ex post recipient communication in the form of an unrestricted written message. The dictator game was chosen over the more popular ultimatum game in order to avoid confounding altruism with risk aversion or false beliefs. Moreover, we wanted to study the generosity of the divider rather than the recipient's willingness to engage in costly punishment. According to Koenigs et al. (2007), charity and punishment engage

Results

Fig. 1 shows the distribution of donations in the two treatments. On average, subjects in the control group donated 24.84% of the endowment to the recipients. In the feedback group the average donation was 34.12% of the endowment, an increase of almost 40%. The difference between the groups is statistically significant at the 5% level (p=.023 according to a nonparametric Mann–Whitney test; two-sided p value).3

Discussion

Our findings demonstrate that anticipated verbal feedback in the form of anonymous written messages induces a substantial increase in altruistic behavior towards otherwise defenseless opponents. Since an anonymous written message is a mild form of feedback compared to naturally occurring personal communication, the identified effect is likely to underestimate the behavioral impact of anticipated emotional feedback in more realistic settings.

Comparing the donation level in our feedback condition

Acknowledgments

We praise Emma Mårtensson and Björn Tyrefors for their research assistance and two anonymous referees and an editor for their helpful comments. We also express our gratitude to the Torsten and Ragnar Söderberg Foundation, the Jan Wallander and Tom Hedelius Foundation, and the Swedish Research Council for financial support. The authors accept blame for any remaining errors or omissions.

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