By Dr. Becker
A study at the University of Stirling in the U.K. demonstrated that capuchin monkeys will refuse food treats offered by selfish humans. According to study author James Anderson, a comparative psychologist, the human trait of developing impressions about others based on our observations of them, is probably found in other species as well.
Monkeys Refuse Treats from Uncooperative Humans
For the study, published recently in Nature Communications1, Anderson selected capuchins because they are known to be highly social and cooperative. The monkeys looked on as one person either agreed or refused to help another person open a jar that held a toy. Then both people offered a food treat to the monkey, who was allowed to take a treat from only one person.
When the capuchins were offered a treat from pairs that included a helpful human, they were just as likely to take a treat from either person. But when offered a treat by people who had refused to help their experiment partner, all seven monkeys were more likely to refuse it.
The researchers tested different scenarios to try to discover what actually caused the capuchins to refuse treats. They instructed the “refusers” to busy themselves opening their own jars as a way of avoiding helping their partners. In this instance, the monkeys showed no bias against those who didn’t help, but continued to avoid accepting treats from people who were available to help but did not.
Can Capuchins Identify Undesirable Social Partners?
According to Kiley Hamlin, a developmental psychologist at the University of British Columbia in Vancouver, “Explicit refusal to help is a signal that you’re dangerous, that you’re negative.” He says this most recent study indicates that the ability to identify undesirable social partners is instinctual for certain species.
Jennifer Vonk, a comparative psychologist and author of a study of chimpanzees published in 2008, believes the capuchin study results shouldn’t be taken as proof that monkeys understand human character traits. Vonk believes additional tests are needed to further explore the capuchins’ preferences and motivations.
She would also like to see more studies on other types of social and even non-social animals as well, to see if watching social interactions impacts their behavior.