Morally good content was transmitted with greater fidelity than neutral or morally bad ones; the communication of moral virtue might serve to avoid negative impression formation & promote social bonding

Social transmission favours the ‘morally good’ over the ‘merely arousing’. Joseph M. Stubbersfield, Lewis G. Dean, Sana Sheikh, Kevin N. Laland & Catharine P. Cross. Palgrave Communications 5, Article number: 3 (2019). https://www.nature.com/articles/s41599-019-0269-y

Abstract: Moral stories are pervasive in human culture, forming the basis of religious texts, folklore, and newspaper articles. We used a linear transmission chain procedure to test three competing hypotheses: (1) that moral content in general is preferentially transmitted between individuals compared to non-moral content; (2) that negativity bias leads specifically to morally bad content being preferentially transmitted; and (3) that a bias towards pro-social information leads specifically to morally good content being preferentially transmitted. While we found no support for a bias for moral content in general, we did find that morally good content was transmitted with greater fidelity than neutral or morally bad content, with ratings of morally good content but not morally bad content predicting transmission. Moral content, therefore, appears to be particularly culturally potent when it describes the ‘virtuous’ rather than the ‘sinful’. A second study repeated the first but also tested the influence of physiological arousal on transmission by measuring the electrodermal activity of participants. This study also found that morally good content was transmitted with greater fidelity than neutral or morally bad content and that physiological arousal had a negative effect on transmission with more arousing material being less faithfully transmitted. These results suggest that the communication of content relating to moral virtue might serve to avoid negative impression formation and promote social bonding, and that this might partially explain the ubiquity of moral content in human culture.



Introduction

Information about morality—defined by Ayala (2010) as “value judgments concerning human behaviour” (p. 9016)— pervades human culture, in religious texts, folklore, fables and news stories. Moral information might be an explicit proclamation of what is moral or amoral, or a more implicit illustration of the moral norms of a social group. Morality is characterised by some authors as an adaptation, built upon emotions that are themselves adaptive, with specific moral codes emerging via gene-culture coevolution (Gintis et al., 2008; Graham et al., 2013; Norenzayan, 2014). While disagreement exists about the sequences of events and selection pressures underpinning the human capacity for morality, there is general agreement that the emergence and evolution of moral codes and norms is only possible through cultural transmission (Ayala, 2010; Haidt and Joseph, 2004, McNamara et al., 2019). The process by which moral content is embedded into culturally transmitted stories and artefacts is poorly understood, however. Here, we present two studies investigating cognitive content biases towards moral information.

A cognitive content bias is a predisposition that humans have for attending to, recalling, or re-producing, certain kinds of information. (Boyd and Richerson, 1985; Barrett and Nyhof, 2001; Henrich and McElreath, 2003). Evolutionary psychologists argue that such biases exist because they were adaptive in ancestral environments (e.g., tracking social relationships in complex groups), and that they modify the content and structure of cultural knowledge and artefacts, which makes them increasingly transmittable (Barrett and Nyhof, 2001; Laland and Brown, 2011; Mesoudi, 2016). Studies have demonstrated biases for a number of types of content: ecological information relevant to health and survival, hereafter survival content (Nairne, 2010; Stubbersfield et al., 2015); information relevant to social relationships and interaction, hereafter social content (Mesoudi et al., 2006; Stubbersfield et al., 2015), and information evoking an emotional response, hereafter emotional content (Eriksson and Coultas, 2014; Heath et al., 2001; Stubbersfield et al., 2017). A number of studies investigating biases in transmission have used the transmission chain, or serial reproduction, paradigm, in which experimental material is passed along a linear ‘chain’ of individuals. First developed by Bartlett (1932), this method allows researchers to assess which types of information are preserved with the greatest fidelity as they are passed along the chain, in turn revealing the biases in social transmission which influence the transmission and evolution of culture (Mesoudi and Whiten, 2008; Mesoudi et al., 2006). While evidence for a number of content biases in transmission has been documented (See Stubbersfield et al., 2018 for a review) a content bias for morally relevant content has yet to be experimentally examined.

Based on Haidt and Joseph’s (2004) moral foundations theory, one might expect a transmission bias for all morally relevant information, because any information relevant to the moral foundations would be salient. This hypothesis has not yet been directly tested but indirect evidence for a bias for moral content comes from the literature on impression formation. Wojciszke et al. (1998) for example, found that morality-related information played a more important role in global impression formation and was more cognitively accessible than competence-related information. Ybarra et al. (2001) found that participants were more sensitive to person-relevant information from the morality domain than the competence domain. Van Leeuwen et al. (2012) used a memory confusion paradigm and found that participants spontaneously categorised along a morality dimension but not along a competence dimension. Morality also influences the perception of specific actions: Pizarro et al. (2006) gave participants one of two vignettes—the first about a man intentionally leaving a restaurant without paying and the second about a man who forgot to pay for his meal. Participants who read the vignette with the intentional— but not the accidental—moral transgression distorted the recalled amount to be larger than it was when asked for the size of the bill. Taken together, these studies suggest that moral content is particularly salient when forming impressions of other people and their actions.

Another known bias which could influence the transmission of moral content is a general negativity bias. Research on memory, perception, decision making and impression formation has suggested that negative entities (such as events, objects or personal traits) are more salient than their positive counterparts (Baumeister et al., 2001; Rozin and Royzman, 2001). It has been suggested that this bias is adaptive, because negative entities are likely to incur greater costs on an individual than positive entities incur benefits (Rozin and Royzman, 2001). A suggestion supported by Fessler et al. (2014), who found that participants were more credulous of negatively framed than positively framed information and that negative content was over-represented in a corpus of online urban legends and supernatural beliefs. Bebbington et al. (2016) also demonstrated a transmission advantage for negatively valenced content over positively valenced content, and found that ambiguous content is more likely to become negative than positive through transmission. Similarly, Walker and Blaine (1991) used a naturalistic “field-experiment” to demonstrate that rumours forecasting unpleasant consequences have an advantage in social transmission over rumours forecasting pleasant consequences. In addition, other studies have found a negativity bias in emotional expression in the arts (see Brand et al., 2019; Morin and Acerbi, 2017). Based on these findings it is feasible that content featuring immoral behaviour will be more salient and better transmitted than content featuring virtuous behaviour, because immoral agents could be perceived as more hazardous than moral agents are beneficial.

Alternatively, a positivity bias might shape the transmission of moral content. Experimental research has found a preference for choosing to transmit positively valenced vignettes over negatively valenced equivalents (van Leeuwen et al., 2018). Studies using “real world” data have found an advantage for positive content, with positively valenced messages being more frequently and more widely shared on social media than negative content (Ferrara and Yang, 2015a; Ferrara and Yang, 2015b; Fu et al., 2016) and urban legends featuring amusing content being more common than those featuring other, negative emotions (Stubbersfield et al., 2018). In addition, research has shown that children seek out and transmit content which supports a positive, pro-social, evaluation of their in-group over other types of information, including negative information about their out-group (Over et al., 2017). Therefore, the possibility of virtuous content being advantaged in transmission should also be considered. We therefore examine the transmission of both morally good content and morally bad content. In Study 1 we test three alternative hypotheses relating to the transmission of moral information in a linear transmission chain. In Study 2 we extend on Study 1 by including a measure of physiological arousal in order to examine the role of emotion in the transmission of moral information.