An evolved cognitive bias for social norms

Abstract

Social norms are a widely used concept for explaining human behavior, but there are few studies exploring how we cognitively utilize them. We incorporate here an evolutionary approach to studying social norms, predicting that if norms have been critical to biological fitness, then individuals should have adaptive mechanisms to conform to, and avoid violating, norms. A cognitive bias toward norms is one specific means by which individuals could achieve this. To test this, we assessed whether individuals have greater recall for normative information than for nonnormative information. Three experiments were performed in which participants read a text and were then tested on their recall of behavioral content. The data suggest that individuals have superior recall for normative social information and that performance is not related to rated importance. We discuss how such a cognitive bias may ontogenetically develop and identify possible hypotheses that distinguish between alternative explanatory accounts for social norms.

Introduction

The social life of humans is guided by social norms. These cultural rules shape and structure our daily behaviors, guiding much of what we do and do not do by prescribing what behavior is acceptable (Cialdini & Trost, 1998). Yet despite their widespread use in psychological theories (e.g., Hechter & Opp, 2001), the functions of normative behavior are not empirically well established from either an evolutionary or a proximate perspective and have tended to be taken for granted as a social phenomenon. Of course, some social patterns of behavior that are labeled as social norms may not be learned behaviors at all (e.g., incest avoidance), but a vast array of social patterns of behavior are self-evidently learned.

There are a number of theoretical models that may account for the functions of social norms that we can outline briefly here. One simple account of social norms is that they are the result of social learning (Bandura, 1977), with some behaviors becoming particularly prevalent in a population, perhaps due to, in some sense, a “tipping-point” effect (Gladwell, 2000) in which their distributions are curtailed only by group boundaries. A slightly varied version of this model views some norms as a result of a corresponding meme (Dawkins, 1976). Alternatively, “normative conformity” (Henrich, 2004) may have an ancient phylogenetic history; many gregarious animal species demonstrate a simple version of conforming behavior, “following the herd” to avoid exposure to predators (Hamilton, 1971). However, people's responses to social norms, violations of norms, and changes in norms suggest that norms are not due solely to incidental group boundaries or selfish herds, although these may play a role.

A second more sophisticated account of norms suggests that they may result from an evolved strategy to avoid the costs of individual learning: If successful behaviors tend to become widespread, then adopting widespread behaviors should tend to result in the acquisition of beneficial behaviors (Boyd & Richerson, 1985). Furthermore, Richerson and Boyd (2005) have argued that a conformism bias can reduce the chances of individuals making errors when sampling for prevalent beneficial behaviors. Henrich and Boyd (1998) have shown that a conformity bias can evolve if humans existed in an environment that fluctuated (although not too rapidly), provided inference by individuals from environmental cues is neither too accurate nor too error prone. In fact, they show that a conformity bias is likely to evolve even when reliance on social learning is limited, and that a conformity bias can enhance reliance on social learning. Empirically, it has been shown that individuals increasingly rely on a conformist tendency as task importance increases (Baron, Vandello, & Brunsman, 1996).

A third account is that certain behaviors may achieve some form of symbolic status for a group, such that adopting the behavior is required to be considered part of the ingroup (Boyd & Richerson, 1987, Fitch, 2000). The ingroup mechanism is powerful in humans and is easily elicited, and once a behavior is seen as a badge for the group, adopting it would be critical to full group membership. Prapavessis and Carron (1997) have shown that an increased sense of rapport and trust can be facilitated from perceptible similarity due to norms. Public signals could enhance and stabilize this effect, either by requiring group members to invest resources of time and/or energy in displaying membership cues (e.g., religious rituals; Sosis, 2003) or by at least publicly advertising group allegiance, making switching membership costly by virtue of having to convince the new group that the individual's allegiance is substantial. In relation to this, Fessler (2004) has argued that behavioral correlates of shame indicate an individual's awareness of violating a norm, signaling both awareness and contrition. A fourth possible cause of social norms, group coordination and cohesiveness, driven by intergroup competition for resources and direct conflict (Bugental, 2000), would benefit from tangible markers showing group allegiance. Such coordination may be the result of Nash-equilibrium-type situations, where one particular goal or behavior requires group coordination to attain and represents a stable optimal choice for the group as a whole.

Finally, norms may be the product of cooperative group behavior, perhaps even being elevated to moral norms or rules (Boehm, 1999, Sober & Wilson, 1998, Wilson, 2002). Wilson and Kniffin (1999) have shown that a conformity bias can evolve due to between-group selection, while Richerson and Boyd (2005) have argued that a conformity bias can serve as a means at the cultural level to filter errors that individuals make when acquiring prevalent behaviors. Conformism plays an important theoretical role in the evolution and maintenance of cultural evolution, and of cooperative behaviors so derived (Richerson & Boyd, 2005). In such cases, nonconformity constitutes a form of free riding and requires a deterrent. Punishment of norm violators appears to be a near-universal trait of humans (Brown, 1991). Violations of norms often carry negative consequences ranging from social disapproval and gossip (Acheson, 1988, Ellickson, 1991, Kniffin & Wilson, 2005) to exclusion and expulsion from groups (Boehm, 1999, Brown, 1991), even extending to murder on occasions (Boehm, 1993, Boehm, 1999, Brown, 1991). Studies such as those by O'Gorman, Wilson, and Miller (2005), Price, Cosmides, and Tooby (2002), and Wilson and O'Gorman (2003) provide support for the view that humans are predisposed to react negatively to norm violations, while laboratory experiments show that individuals willingly incur costs to punish, even when there are no further opportunities to interact with the same individuals (Fehr & Gachter, 2002).

Centrally, each of these accounts of norms, with the exception of “viral” and selfish herd accounts, leads to the prediction of a conformity bias in human cognition facilitating enhanced recall of normative information. Of course, behavioral conformity is a well-established finding in social behavior, demonstrated to be quite powerful when activated (e.g., Asch, 1956, Sherif, 1936). However, a cognitive bias that increases access to knowledge of normative behaviors following the observation of such behaviors is only required if there is some inherent value in the normative behaviors. That is, norms due to viral processes should not obviously produce a cognitive bias for normative behavior, whereas selfish herd conformity is beneficial only while a norm is being manifested behaviorally. Only the gene-culture, membership, and cooperative norms models consistently predict a cognitive bias for recall of normative information.

The goal of the present study was to test the hypothesis that humans have enhanced cognitive access to normative information, specifically that individuals have better recall of normative than nonnormative information. To examine the hypothesis, we conducted three experiments in which participants were asked to read through a text and were then tested on their recollection of diverse social information in the text, which differed in whether it was normative or not. Across these experiments, we varied how we tested recall, with the assessment of participants taking the form of multiple-choice responses in Experiment 1 and cued-recall responses in Experiments 2 and 3. In addition, in Experiment 3, we examined whether perceived importance of normative information affected recall success.

The text that we used was an aggregated set of passages derived from an ethnographic account of people living on the Polynesian island of Tikopia (Firth, 1936). This was chosen because it was presumably unfamiliar to the participants due to its content being highly distal from their own cultural knowledge, thus reducing the likelihood of participants extrapolating their own norms to interpret the specific behaviors of individuals recounted in the text. If the material had been based on Western cultural norms, participants would have been aware of normative behaviors, even if no normative information was presented. Thus, it was critical to present unfamiliar social information.

Using text as the stimulus medium may seem to be an evolutionarily incongruous means of presenting social information, but given that reading is a successful medium for evoking imagery and experiences in humans (Gottschall & Wilson, 2005), as exemplified by the popularity of novels, it was considered a more tractable and pragmatic procedure than alternatives such as creating a complex social environment in which to immerse participants. Furthermore, Nairne, Thompson, and Pandeirada (2007) have shown that even recall of specific words can be affected by the fitness relevance of those words, demonstrating that text-based stimuli can be valid for testing evolutionary hypotheses.

We also examined whether there is a sex difference in the recall performance of normative information. Research generally shows that females have a greater aptitude for, and display a greater orientation toward, social affairs (Geary, 1998). However, we did not expect a sex difference for the processing of novel social norms. Both males and females should be equally vigilant in attending to social norms because ignorance of norms is likely to have had similar effects on the fitness of males and females in the environment of evolutionary adaptedness (Bowlby, 1969, Tooby & Cosmides, 1992). Even though males might seem more likely to cognitively attend to outgroup norms due to their more immediate involvement in group conflicts (and perhaps other-group contacts), females in hunter–gatherer societies often move to a new group when they reach marriageable age (Geary, 1998), which suggests a need for females to also have an ability to attend to novel social norms.