Chimpanzees consider intent when judging wrongdoing in others

An international team of researchers has found evidence that suggests chimpanzees consider intent when judging the wrongdoing of others. In their paper published in the journal Biology Letters, the group describes two types of experiments they conducted with captive chimpanzees.

Prior research has shown that humans value the role that intent plays in acts of wrongdoing. In most countries, legal rules separate murder from manslaughter, for example. Those judging must decide if the perpetrator truly meant to kill the other person, or if it was an accident due to their negligence. In this new effort, the researchers sought to find out whether chimpanzees make the same sort of judgments.

In the first experiment, chimps were taught to give their handlers a tool that they had received in exchange for a favorite treat. But there was a catch: Sometimes, the researchers would present a less desirable treat and and demonstrate to the chimp that on some occasions, they had no choice between two options, but other times they did. In this experiment, the chimps were tested on whether they were able to judge the intent of the handler—was he or she offering a less favored treat on purpose, or was it beyond his or her control?

In studying the reaction of the chimps, the researchers found that they very clearly understood the difference between being offered a second-rate treat out of malice or indifference, and an inability to provide the best treat. When it was clear a handler could have offered a better treat but chose to not do so, the chimps responded by spitting at him or her.

In the second experiment, the researchers again offered treats, but this time, one handler hid a preferred treat where a second handler could not see it but the chimp could. In some cases, the second handler made it clear to the chimps that he or she knew what was going on when offering a second-rate treat, and in other cases, it was clear the second handler had no knowledge of the hidden treat. In this example, the chimps did not seem to care about the circumstances and behaved the same in either case.

The researchers suggest that chimpanzees consider intent when judging whether they have been wronged by others.