Factors influencing imitation of manipulatory actions in chimpanzees (Pan troglodytes)

The purpose of the study was to investigate what kind of factors determine the degree of difficulty for chimpanzees (Pan troglodytes) when they imitat e actions. Five adult chimpanzees were instructed to perform 48 arbitrary m anipulatory actions consisting of different bodily motor patterns and objec t directionality. Results showed that actions in which an object is directe d toward another external location (another object and one's own body) were easier to perform than those that involved manipulating a single object al one. Actions involving unfamiliar motor patterns were more difficult to per form than those involving familiar motor patterns that were already present in the subject's repertoire. Error responses were characterized as perseve rative repetition of previously instructed actions. These findings suggest that chimpanzees find the directionality of manipulated objects a more sali ent cue than details of the demonstrator's body movements performing the ma nipulation.