Monkey See, Monkey Do (If the Price is Right)

New research on chimpanzees' problem-solving skills suggests that rather than conforming to the group, individual apes prefer to maintain their own strategies when confronted with a problem. But if made clear that changing strategies will offer a greater reward, the apes will adjust their behavior accordingly.

The research, which was published in the journal PLOS One by animal behavior experts at Max Planck Institute for Psycholinguistics and Evolutionary Anthropology, indicates that chimpanzees are hesitant to abandon their personal preferences, even if a familiar behavior means not conforming to the group.

Scientists tested groups of captive chimpanzees in Germany and semi-wild chimps at an animal reserve in Zambia to see what it would take to get a stubborn chimp to change a personal problem-solving strategy.

Edwin van Leeuwen, lead researcher for the study, trained the chimps to use two different vending machines placed in their enclosures. A minority of each group was made familiar with one of the machines, and a majority of the group was made familiar with the other.

The machines vended one peanut at a time, which could be obtained by placing a wooden ball into an opening on the machine.

First, the researchers studied the behavior of the minority group, curious if the smaller group of chimps trained on one machine would abandon it for an identical machine being used by the rest of the group. None of the chimps, however, gave up on the machine they were familiar with. The second phase of the study changed the profitability of the machine being used by the minority group so that for every one wooden ball inserted into it, a reward of five peanuts came out. When the majority group learned that the other machine was offering a larger payout, they readily switched to the more profitable machine.

"Where chimpanzees do not readily change their behavior under majority influences, they do change their behavior when they can maximize their payoffs," Van Leeuwen said. "We conclude that chimpanzees may prefer persevering in successful and familiar strategies over adopting the equally effective strategy of the majority, but that chimpanzees find sufficient incentive in changing their behavior when they can obtain higher rewards somewhere else."

However, van Leeuwen noted that the behavior of captive and semi-wild chimps may not be representative of truly wild chimps.

"Conformity could still be a process guiding chimpanzees' behavior," he said. "Chimpanzee females, for instance, disperse to other groups in the wild. For these females, it is of vital importance to integrate into the new group. Conformity to local (foraging) customs might help them to achieve this integration."