Effects of different training histories upon manufacturing a tool to solve a problem: insight in capuchin monkeys (Sapajus spp.).

The emergence of novel behavior is a multilayered phenomenon that comprehends distinct processes. One such process is known as insightful problem solving. "Insight" can be explained as the spontaneous interconnection of previously acquired behavioral repertoires. The objective of this study was to investigate: (1) whether capuchin monkeys (Sapajus spp.) do show the interconnection of repertoires, and (2) whether different performances of problem solving could be produced by different training histories. Two repertoires were independently trained: (a) joining two pieces of a tool to manufacture a new tool and (b) raking food with one tool. In the test situation, food was out of reach, and two joinable pieces of a tool, different from the ones used in training, were presented. To solve the problem, the monkeys had to join the two pieces and rake the food with the new manufactured tool. In Experiment 1, one monkey received symmetric training (equal number of sessions) of both repertoires and solved the task, but not in an insightful manner. In Experiment 2, six monkeys were divided into two groups: one group received symmetric training, and the second group had asymmetrical training of the repertoires (unequal number of sessions). Subjects from the symmetric group performed as the monkey in Experiment 1; subjects from the other group showed a sudden insightful solution of the problem. The different performances in the same problem situation can be explained in terms of the behavioral history provided to each group of subjects.