Chimpanzees fail to plan in an exchange task but succeed in a tool-using procedure

Planning has long been considered a uniquely human capacity. Lately, however, it has been shown that apes and a corvid species act now to derive a material future benefit. Since primates are highly social animals and their sociality is considered a strong selective force that resulted in complex cognitive capacities, planning is also expected in social situations. Unfortunately, prompting from social partners cannot be excluded in a social setting. Therefore, we controlled for this factor by testing the capacity to plan in chimpanzees using an exchange paradigm, that involves both a material and a social component, and a tool-use paradigm, similar to the one used on two other ape species. All chimpanzees failed to plan in the exchange task, but three individuals showed planning behavior in the tool-use task. Our methods controlled for the fact that chimpanzees were not prompted by the visibility of the reward at the moment of planning and also could not repeat a previously acquired routine. The best interpretation for our results is that chimpanzees can plan. However, planning was limited to the situation where the action to attain the future benefit only depended on a chimpanzee's own behavior. (c) 2008 Elsevier B.V. All rights reserved.