To bet or not to bet? Decision-making under risk in non-human primates
Résumé
Animals deal with predictable and unpredictable events on a daily basis. Yet
our knowledge of the cognitive processes involved in decisions remains limited. We
tested capuchins, macaques and orang-utans in a food-gambling task to investigate
whether or not individuals estimate the chances of different outcomes. Results
highlighted that gambling decisions were negatively induced by the probability of
losing and the frequency of previous losses, and positively induced by the probability
of gaining. Actual decisions were consistent with first order stochastic dominance. The
study of second order stochastic dominance revealed that macaques were risk-prone
whereas capuchins and orang-utans were risk-adverse. We detected responses comparable
to the hot-hand effect, a bias found in humans. Capuchins and orang-utans
exhibited probability distortion and loss aversion, which were not systematically found
in macaques. Given the heterogeneity among individuals, we implemented mixture models and showed that attitudes towards risk and probabilities play complementary and different roles in the three species