Decision making across social contexts: competition increases preferences for risk in chimpanzees and bonobos

Abstract

Context can have a powerful influence on decision-making strategies in humans. In particular, people sometimes shift their economic preferences depending on the broader social context, such as the presence of potential competitors or mating partners. Despite the important role of competition in primate conspecific interactions, as well as evidence that competitive social contexts impact primates' social cognitive skills, there has been little study of how social context influences the strategies that nonhumans show when making decisions about the value of resources. Here we investigate the impact of social context on preferences for risk (variability in payoffs) in our two closest phylogenetic relatives, chimpanzees, Pan troglodytes, and bonobos, Pan paniscus. In a first study, we examine the impact of competition on patterns of risky choice. In a second study, we examine whether a positive play context affects risky choices. We find that (1) apes are more likely to choose the risky option when making decisions in a competitive context; and (2) the play context did not influence their risk preferences. Overall these results suggest that some types of social contexts can shift patterns of decision making in nonhuman apes, much like in humans. Comparative studies of chimpanzees and bonobos can therefore help illuminate the evolutionary processes shaping human economic behaviour. . Understanding the role of social context in shaping decision-making strategies is particularly important for biologists and psychologists who are interested in understanding behaviour in the real world, as gregarious species like primates must constantly make value-based decisions in the company of others. While cooperation in nonhumans has received increasing attention, little comparative research has examined the role of social context in shaping decisions when an individual's payoffs do not directly depend on their partner's behaviour. In the current study we therefore examine the impact of social context on risk preferences in chimpanzees, Pan troglodytes, and bonobos, Pan paniscus, our closest phylogenetic relatives.Studies of social context and decision making in humans have generally been motivated by evolutionary hypotheses concerning how the presence or absence of certain social partners might alter how decision makers value resources. In one study, Wilson & Daly (2004) found that men who viewed images of attractive women had steeper temporal discounting rates, devaluing the future much more heavily than men who viewed unattractive women or cars. That is, looking at attractive women made men more impulsive or present oriented, possibly because the attractive women cued men into the possibility that current possession of goods could increase mating opportunities. Social context also modulates people's willingness to take economic risks (or accept variability in payoffs). For example, men became more likely to choose risky options when their choices were watched by an observer of equal status, compared to when relative status was ...

Bonobos and chimpanzees exhibit human-like framing effects

“…Together with comparative studies of the endowment effect [13,14], risk sensitivity [15] and ambiguity aversion [16,17], our work suggests that core features of human decision-making may reflect biological predispositions and that experience with monetary markets may not be necessary for components of human economic behaviour to emerge. Although chimpanzees and bonobos exhibited differences in risk preferences in previous studies [18][19][20][21], we found no differences in their responses to framing. This aligns with previous work indicating that chimpanzees and bonobos may differ specifically in cognitive capacities relevant to their natural socioecology but show broad commonalities in cognition across many other contexts [22].…”

Gambling primates: reactions to a modified Iowa Gambling Task in humans, chimpanzees and capuchin monkeys

“…Most of the work on risk preferences in primates has used a payoff structure where the “risky” and constant options had equivalent overall rewards and only varied in the way those rewards were distributed, as in our EPGT condition (Rosati and Hare 2012; Heilbronner et al 2008). Typically, the “risky” option involves a 50 % probability of getting the highest value reward and a 50 % chance of getting the lowest value reward; the average payoff was the same between this and the “safe” option.…”

“…Chimpanzees present a more complex picture. In the “risky” payoff structure described above, chimpanzees have been classified as risk-prone, preferentially selecting the more variable option with this payout structure (Heilbronner et al 2008; Rosati and Hare 2012). In contrast, in our EPGT condition, where both options also had the same average payoff, chimpanzees were either variance avoidant or indifferent.…”

Comparative Developmental Psychology: How is Human Cognitive Development Unique?

“…Increasing evidence suggests that adult chimpanzees and bonobos actually differ in a set of cognitive traits related to foraging, including levels of feeding tolerance (Hare, Melis, Woods, Hastings, and Wrangham, 2007;Wobber, Wrangham, and Hare, 2010b), tool use abilities , spatial memory (Rosati and Hare, 2012b), and patterns of value-based decision-making (Heilbronner, Rosati, Hare, and Hauser, 2008;Rosati and Hare, 2011, 2012a …”