Chimpanzees have been shown to share another of our core human characteristics: the ability to assess intent after being wronged. When someone hurts us, the issue of whether it was intentional or unintentional is crucial to our reaction. It’s for this reason that murder and manslaughter are two distinct crimes with quite different consequences. Ignoring other people’s intentions and penalizing them for something they couldn’t control is a bad idea. However, considering such difficulties necessitates a complex theory of mind, which is normally reserved for animals.
However, two studies published in Biology Letters show that chimps may occasionally comprehend the distinction, take it into consideration, and apply it to humans as well as their own species. Human experimenters offered food items to chimps in a sanctuary, according to Professor Jan Engelmann of the University of California, Berkeley, and co-authors. The chimps were taught that the meals were theirs in exchange for returning a tool that had been provided to them. They might choose whether or not to accept the meal and complete the mission.
Two foods were displayed in the first experiment. An individual chimp’s favored meal had already been determined by the experimenter. The meals were placed in some cases such that the researcher could access both, but in others, the favored food was locked in a box that the experimenter would unsuccessfully seek to unlock, a fact that the experiment’s design clearly conveyed to the chimp.
Chimpanzees who viewed the experimenter as having no option but to give them the less desired food were more likely to accept it than those who observed the scientist knowingly handing them second-best food. When the chimps believed their deprivation was planned, the researchers monitored their emotional responses and found greater signs of hostility, such as spitting at the experimenter.
“To our knowledge, this is the first indication that chimps, like humans, evaluate social treatment not just in terms of outcome—for example, whether they received a preferred or non-preferred item—but also in terms of causal history,” the researchers write. Prior research yielded similar results, but flaws in the experimental design allowed for alternate interpretations.
The second test was a little more subtle. In half of the trials, one of the researchers hid a favorite food item where no other human could see it but the chimp could. As far as the person supplying the food was aware, they were feeding the chimp with the finest that was available. The experimenter on the other side was well aware of the favored item and decided not to deliver it. On this occasion, the apes were not as forgiving. Their theory of mind didn’t seem to include the fact that the human was unaware of the pleasant reward that the chimp could see but the human couldn’t.
In this experiment, whether the individual knew there was an alternative or not, their reactions to being served the second-best food were the same. Some individuals may be glad to find that chimps’ understanding of human psychology isn’t so advanced that they can understand what humans know and don’t know. They may be closer than we believe, but not by much. Anyone who feels this way should examine how many people would do better on the second test if they understood that the person who disappointed them did it out of ignorance rather than malice.
