Like some humans, chimpanzees and bonobos exhibit emotional
responses to outcomes of their decisions by pouting or throwing angry tantrums
when a risk-taking strategy fails to pay off, according to research published in the open access journal PLOS ONE by Alexandra Rosati from Yale
University and Brian Hare from Duke University.
The researchers assessed the emotional responses and
motivation of chimpanzees and bonobos living in African sanctuaries. Rosati
explains, "Psychologists and economists have found that emotions play a
critical role in shaping how humans make complex decisions, such as decisions
about saving or investing money. But it was not known if these processes are
shared with other animals when they make decisions about their important resources--such
How the study was
The apes in this study faced two different types of
problems: one where they made choices about whether to wait to obtain larger
rewards, and one where they made choices about whether to take a chance to
obtain a high-quality treat, but risk obtaining a non-preferred food item if
their gamble did not pay off.
The scientists found that both species displayed emotional
responses to the outcome of their choice, but chimpanzees were more patient and
likely to take risks than bonobos.
When their choice yielded the less preferred outcome, both
species displayed negative emotional responses including vocalizations similar
to pouts and moans, scratching, and banging--a type of tantrum thought to
reflect anger in apes. In the risky choice task, the apes even tried to switch
their choice after the fact when they realised they had made a losing gamble,
but never did so when their risk-taking paid off.
Some of the emotional and motivational responses displayed
by the apes were species-specific while others reflected individual differences
in the animals.
Based on their results, the authors conclude that apes do
exhibit emotional responses to decision-making, like humans. They add that
further research is needed to determine whether these emotional responses to
outcomes can change the apes' future choices and decisions.