STIMULUS ENHANCEMENT AND SPREAD OF A SPONTANEOUS TOOL USE IN A COLONYOF LONG-TAILED MACAQUES

In a captive group of long-tailed macaques, tool-using behavior by a s ingle competent individual had a significant effect on the synchronous manipulative behavior of naive animals. Group members engaged in mani pulations on the same object class more frequently during times when t he model was working than when it was not. The form of their behavior, however, in no way resembled the technique used by the model. All thr ee animals that later became successful tool users were among the few subjects that exhibited a significant increase in manipulations on the same object class while the model was working. Possible causal relati onships between this stimulus enhancement and the transmission of the new behavior to other group members are analyzed and discussed.