Social disappointment explains chimpanzees' behaviour in the inequity aversion task.


Journal Article

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.

Full Text

Duke Authors

Cited Authors

  • Engelmann, JM; Clift, JB; Herrmann, E; Tomasello, M

Published Date

  • August 2017

Published In

Volume / Issue

  • 284 / 1861

PubMed ID

  • 28835562

Pubmed Central ID

  • 28835562

Electronic International Standard Serial Number (EISSN)

  • 1471-2954

International Standard Serial Number (ISSN)

  • 0962-8452

Digital Object Identifier (DOI)

  • 10.1098/rspb.2017.1502


  • eng