In the test, the apes were given the chance to obtain a banana while risking a lettuce leaf. When their risk paid off, the apes were happy, but when it failed they pouted and sulked like humans.
"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," said Alexandra Rosati, from Yale's Department of Psychology. "But it was not known if these processes are shared with other animals when they make decisions about their important resources - such as food."
The study appears in the open-access science journal PLOS ONE.