Publications [#328850] of Michael Tomasello

Journal Articles

1. Engelmann, JM; Clift, JB; Herrmann, E; Tomasello, M, Social disappointment explains chimpanzees' behaviour in the inequity aversion task., Proceedings. Biological sciences, vol. 284 no. 1861 (August, 2017), pp. 20171502 [doi]
   (last updated on 2024/04/20)

   Abstract:
   Chimpanzees' refusal of less-preferred food when an experimenter has previously provided preferred food to a conspecific has been taken as evidence for a sense of fairness. Here, we present a novel hypothesis-the social disappointment hypothesis-according to which food refusals express chimpanzees' disappointment in the human experimenter for not rewarding them as well as they could have. We tested this hypothesis using a two-by-two design in which food was either distributed by an experimenter or a machine and with a partner present or absent. We found that chimpanzees were more likely to reject food when it was distributed by an experimenter rather than by a machine and that they were not more likely to do so when a partner was present. These results suggest that chimpanzees' refusal of less-preferred food stems from social disappointment in the experimenter and not from a sense of fairness.