Chimps Know How to Deceive People

Jan. 24, 2007 — Like a so-called mind reader who is actually just a clever observer of human behavior, chimpanzees can predict our actions by figuring out what we see and hear, according to recent studies.

The research has also determined that chimps may use this skill to their own advantage by intentionally deceiving us, primarily by manipulating whether or not others can or cannot see and hear them.

Scientists have long speculated that these primates are clever and can be sneaky, but the latest findings, published in recent Cognition and Journal of Comparative Psychology issues, indicate they are more aware of others’ perceptions than previously realized.

One chimp tactic is something that young children also use — gaze following.

"Chimpanzees look in the direction someone else is looking and predict future behavior based on that," scientist Vanessa Woods told Discovery News.

Woods, who works on the ongoing project, is a researcher in the Hominoid Psychology Research Group at Germany’s Max Planck Institute for Evolutionary Anthropology and is the author of the forthcoming book, "It’s Every Monkey for Themselves."

The research team devised two experiments to test first, if chimps know what others can see and second, if they know what others hear. The "other" in this case was a human sitting in a windowed ticket taker's-style booth. Holes at the sides of the booth allowed chimps to snatch food, which the person would often grab, as though in competition with the animal.

For the initial series of experiments, the chimps did everything from hiding behind barriers to doing a bit of Academy Awards-worthy acting to get the food. For the latter, they would back away from the food and the person, as though they were not interested. They would then crouch down, sneak away to the side and then snatch the food.

For the second series of experiments, the researchers gave the chimps a choice between sticking their hands through opaque or clear tubes to grab food. The primates always chose the opaque tube, until the scientists made it so that the tube emitted a loud noise whenever the chimps stuck a hand in it. The chimps would then try to deceive the human again, before reaching through the silent tube for their food reward.

Woods pointed out that it’s been known other species, such as ravens, can deceive, but the recent work provides evidence that at least one animal intentionally plans their deception based on their knowledge of what others can and cannot see and hear.

She explained that these skills are useful in the wild when chimps have to quietly patrol their borders or grab food — concealed by a natural barrier such as a tree trunk — while others are watching.

Marc Hauser, director of Harvard’s Cognitive Evolution Lab and co-director of the university’s Mind, Brain & Behavior Program, told Discovery News that the study results are "wonderful," saying, "These results all add to the growing knowledge that animals seem to have far greater awareness of what others know than we had previously anticipated."

Roger Fouts, director of university research at Central Washington University, who has worked with chimps for decades, said he is not surprised by the findings.

"Anyone who has studied free-living or captive chimpanzees who are not in conditions of extreme deprivation, so typical in most laboratories, will not be surprised by these results," he said.

Woods and her colleagues continue to study chimps and other primates, and are now investigating the effects of domestication on chimpanzee social skills, chimp decision-making, temperaments and more.