Chimps, people think alike

Our closest genetic living relatives, the chimps, may not be so different from us after all.

Scientists presented research on Sunday at a talk entitled “Primate Theory of the Mind,” suggesting that chimps may posses many of the same higher-order thinking patterns that humans do. Cognitive scientists have long since debated whether primates have the cognitive ability to understand others in terms of their intentions, such as their beliefs and desires — dubbed “the theory of mind.” Studies presented at the talk about false and true belief, “chimp chess” and moral systems — which reveal behavior contingent on a chimp’s ability to realize others’ mental states — represent strong evidence of the theory of mind, the scientists said.

The final in a series of six lectures, the talk brought a close to the department of Cognitive Science’s workshop series, “The Evolution of Social Psychology,” held this past weekend. The lectures featured speakers from diverse fields such as anthropology, neuroscience and philosophy, who probed questions on emotion, morality and decision-making.

Josep Call, a scientist at the Max Planck Institute for Evolutionary Anthropology in Germany, presented a study using the concept of “chimp chess.”

In the study, two monkeys were shown two boxes containing food that hidden from view. One contained “high-quality” or desirable food, while the other contained low-quality food. The chimps took turns guessing the box in which the desired food was contained, he said. The experimenters found that the chimps would base their guesses on their partner’s behavior — showing that they are cognizant of the other chimp’s mental state, Call said.

“Chimps know what others can and cannot see … in the immediate past,” he said.

In another of Calls’ studies, monkeys were found to prefer eye contact when cooperating to obtain food, but avoid it if they were stealing food. This shows an inherent moral system that is similar to, but less sophisticated than, a human’s, Call said.

“Experiments are like drugs,” he said in a lighter moment of the lecture. “If you use the right one, it can be pleasurable. If you use the wrong one, it can give you a headache.”

But unlike humans, chimps cannot mentally represent a false belief.

Drew Marticorena, a graduate student at Duke University, tested the concepts of true belief and false belief using a “hide the lemon” setup.

“Monkeys like citrus,” he said, referring to the assumption that the monkey would search for the fruit.

In half of trials, the participating chimp knew where the lemon was placed, while in the other half, it was uninformed, he said. The lemon was then moved to another location — which the chimp witnessed in half of the trials and did not witness in the other half, creating a “false belief” about the lemon’s true location. An onlooking chimp was not able to predict where the other chimp would “search” in the misinformed condition, showing that they did not understand their competitor had a false belief, Marticorena said.

Amy Jones ’09, a cognitive science major who attended the conference, said she especially enjoyed the talk “Primate Decision-Making and Irrationality.”

“These are the leading experts in cognitive fields, and to bring them together really provides a coherent picture of cognitive science,” she said.

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