Chimps solve puzzles for fun

Researchers studying chimpanzees at Whipsnade Zoo have found that the apes like to do puzzles even when they get no reward.

The new paper, published early online in the American Journal of Primatology, comes from a collaboration between the Zoological Society of London and Royal Veterinary College. Fay Clark and Lauren Smith found that not only did the chimpanzees use their cognitive challenge device both when they were rewarded with brazil nuts (a chimp delicacy) and when they were just given a token, they in fact played the game more when they got the token rather than food. The device was made up of a series of tubes through which the chimps had to use tools to manoeuvre the reward to the exit pipe at the end.

That the puzzle enhances their psychological well-being is also supported by the fact that they played with each other more when the puzzle was in their cage compared to when it was not there. Self-directed behaviour, such as rough-scratching and nose-wiping, and aggression to others was also used to assess how content the apes were, the hypothesis being that SDB and aggression would decrease with puzzle use. While rough-scratching increased when the puzzle was present, it then decreased the more the puzzle was used. SDB was also higher at the beginning of the study compared to the end, suggesting that the chimps found the task frustrating at first, but benefitted from it more once they had got used to it.

This study shows that, like humans, chimpanzees benefit from problem-solving exercises as shown by reduced aggression and stress, and increased positive interactions. This is linked to exploration and foraging observed in the wild even when no food is brought back, and has similarities to a previous study showing that chimps will work for food even when they can get it for free (contrafreeloading). Problem-solving can be a highly enriching task and this study supports the continued use of zoo enrichment exercises such as hiding food, as well as providing further insight into the cognition of the great apes.

https://doi.org/10.1002/ajp.22141

Clark, FE and Smith, LJ (2013), Effect of a Cognitive Challenge Device Containing Food and Non‐Food Rewards on Chimpanzee Well‐Being. Am. J. Primatol, 75: 807-816