The presence of a potential competitor modulates risk preferences in rats

Although both human and non-human animals, in everyday life, deal with risky decisions in a social environment, few studies investigated how social dimension influences risk preferences (i.e., if consequences on others feeds back over own choice). Here, we assessed whether the presence of a conspecific, acting as a potential competitor for the same food resource, influenced risky decision-making in male rats. Subjects received a series of choices between a safe option (always yielding a small yet optimal reward, solely to itself) and a risky option (yielding a larger but suboptimal reward, one third of times to itself and two third of times delivered to the other half cage); rats were tested twice, both alone and paired with a conspecific, recipient of own-lost food and hence acting as potential competitor. Results showed that focal subjects were more risk-prone when paired with a conspecific than when tested alone. However, rats exhibited also a higher motivational conflict with a competing bystander present than alone: data suggest that the primary drive was to increase "own" food rather than either a competitive or prosocial tendency. Overall, for rats tested in a risky-choice task, a competitive social context increased the salience and attractiveness of larger food outcomes, as observed in humans and great apes. This led to the economically irrational response of selecting the "binge-but-risky" option, notwithstanding uncertainty about the actual recipient of such food.