hide
Free keywords:
-
Abstract:
Recently, Mendes et al. [1] described the use of a liquid tool (water) in captive orangutans. Here, we tested chimpanzees and
gorillas for the first time with the same ‘‘floating peanut task.’’ None of the subjects solved the task. In order to better
understand the cognitive demands of the task, we further tested other populations of chimpanzees and orangutans with
the variation of the peanut initially floating or not. Twenty percent of the chimpanzees but none of the orangutans were
successful. Additional controls revealed that successful subjects added water only if it was necessary to obtain the nut.
Another experiment was conducted to investigate the reason for the differences in performance between the unsuccessful
(Experiment 1) and the successful (Experiment 2) chimpanzee populations. We found suggestive evidence for the view that
functional fixedness might have impaired the chimpanzees’ strategies in the first experiment. Finally, we tested how human
children of different age classes perform in an analogous experimental setting. Within the oldest group (8 years), 58 percent
of the children solved the problem, whereas in the youngest group (4 years), only 8 percent were able to find the solution.
