Chimps do not give in to peer pressure

Chimpanzees are sensitive to social influences but they maintain their own strategy to solve a problem rather than conform to what the majority of group members are doing, a new study has found.
However, chimpanzees do change their strategy when they can obtain greater rewards, researchers found.
Edwin van Leeuwen and colleagues from the Max Planck Institute for Psycholinguistics conducted a series of experiments on chimpanzees in Germany and Zambia.
The researchers studied 16 captive chimpanzees at the Wolfgang Kohler Primate Research Center in Germany (Leipzig) and 12 semi-wild chimpanzees at the Chimfunshi Wildlife Orphanage Trust, a sanctuary that houses more than a hundred chimpanzees under nearly natural conditions in the north-western part of Zambia.

Chimpanzees were trained on two different vending machines. A minority of the group was made familiar with one machine and the majority of group members with the other machine.
Wooden balls were thrown into their enclosure; the chimpanzees could insert these balls into the machines to receive one peanut for each ball.

Van Leeuwen and his colleagues first aimed to replicate previous research and looked whether the chimpanzees in the minority group would change their behaviour toward using the vending machine that the majority of group members used.
However, neither the German nor the Zambian chimpanzees gave up their strategy to join the majority.

In the second study, the profitability of the vending machines was changed so that the vending machine that the minority used became more profitable, now spitting out five rewards for every ball inserted.
Over time, the majority chimpanzees observed that the minority chimpanzees received more peanuts for the same effort and all but one gradually switched to using this more profitable machine.
"Where chimpanzees do not readily change their behaviour under majority influences, they do change their behaviour when they can maximise 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 behaviour when they can obtain higher rewards somewhere else," he said.

The researchers emphasised that these results may be dependent upon the specific trade-offs that were created by the experimental design and that chimpanzees could act differently under the pressures of life in the wild.
"Conformity could still be a process guiding chimpanzees' behaviour," Van Leeuwen 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," he said.
The study was published in journal PLOS ONE.