Social facilitation of eating familiar foods might serve to synchronize eating activities within groups. We aimed to assess whether capuchin monkeys (Cebus apella) are prompted to eat when observing other conspecifics eating a familiar food. Subjects were eight male captive-born tufted capuchin monkeys. One pair of capuchins acted as the demonstrators for other six observer subjects. The input provided by the demonstrators differed in the two experimental conditions. In the Experimental condition, the demonstrator pair was given fresh chow in addition to having access to the leftover food and ate continuously. In the Control condition, the demonstrator pair had access to food leftover from the morning feed and ate very little. The initiation of feeding by the demonstrator pair prompted the initiation of feeding behavior in the observers, and the latter ate significantly more of their leftovers in the Experimental than in the Control condition. The tempo of the social facilitation of eating familiar foods in capuchins support isomorphic coordination, a process that occurs when one individual's activity focuses the attention of another individual to the same activity, thereby increasing behavioral similarity in a group
