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(Phys.org)—A team of researchers from Kyoto University has found that dogs and capuchin monkeys watch how humans interact with one another and react less positively to those that are less willing to help or share. In their paper published in the journal Neuroscience & Biobehavioral Reviews, the team describes a series of experiments they carried out with several dogs and capuchin monkeys and what they discovered about both species social preferences.

Common sense suggests that most people prefer to deal with other people who are fair and in some cases, helpful. In this new effort, the researchers sought to learn if the same might be true of dogs and capuchin monkeys regarding human interactions. To that end, they set up three experiments designed to test how dogs and monkeys reacted to humans behaving rudely.

In the first experiment, a capuchin monkey was allowed to watch a scene in which a person was trying to open a can. After failing, the person asked another person for help—in some cases, the other person complied, and in some cases, they did not. Also in some cases, there was another person present who did nothing, serving as a passive actor in the scene.

In the second experiment, the researchers positioned a capuchin monkey to watch as two people arrived with three balls each. One of the people then asked the other person to give them all of their balls and the other person complied. Next, the person who had given up their balls asked the other to return them—in some cases the other person complied, and in other cases refused.

The third experiment was nearly identical to the second, except it involved dogs, their owners and another person unknown to the dog.

At the conclusion of all three experiments, the people involved (including passive actors) all offered a treat to the monkey or dog that had been observing the action. The researchers report that in all three scenarios, the animals showed a clear disinclination to accept a treat from a person that refused to help with the can or refused to give back the balls, as compared to those that were helpful or fair or were passive actors. The researchers claim this shows that capuchin monkeys and dogs make social judgments in ways similar to human infants, and that it might even offer clues regarding the development of morals in humans.

Explore further Study shows capuchins less receptive to others who refuse to help when asked

More information: James R. Anderson et al, Third-party social evaluations of humans by monkeys and dogs, Neuroscience & Biobehavioral Reviews (2017). James R. Anderson et al, Third-party social evaluations of humans by monkeys and dogs,(2017). DOI: 10.1016/j.neubiorev.2017.01.003 Abstract

Developmental psychologists are increasingly interested in young children's evaluations of individuals based on third-party interactions. Studies have shown that infants react negatively to agents who display harmful intentions toward others, and to those who behave unfairly. We describe experimental studies of capuchin monkeys' and pet dogs' differential reactions to people who are helpful or unhelpful in third-party contexts, and monkeys' responses to people who behave unfairly in exchanges of objects with a third party. We also present evidence that capuchin monkeys monitor the context of failures to help and violations of reciprocity, and that intentionality is one factor underlying their social evaluations of individuals whom they see interacting with others. We conclude by proposing some questions for studies of nonhuman species' third party-based social evaluations.

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