Social disappointment explains chimpanzees' behaviour in the inequity aversion task.
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.
Type
Journal articleSubject
chimpanzeesevolution
fairness
inequity aversion
social disappointment
Animals
Choice Behavior
Emotions
Pan troglodytes
Reward
Social Behavior
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https://hdl.handle.net/10161/16123Published Version (Please cite this version)
10.1098/rspb.2017.1502Publication Info
Engelmann, Jan M; Clift, Jeremy B; Herrmann, Esther; & Tomasello, Michael (2017). Social disappointment explains chimpanzees' behaviour in the inequity aversion task.
Proc Biol Sci, 284(1861). 10.1098/rspb.2017.1502. Retrieved from https://hdl.handle.net/10161/16123.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Michael Tomasello
James F. Bonk Distinguished Professor
Major research interests in processes of social cognition, social learning, cooperation,
and communication from developmental, comparative, and cultural perspectives. Current
theoretical focus on processes of shared intentionality. Empirical research mainly
with human children from 1 to 4 years of age and great apes.

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