Untrained chimpanzees (Pan troglodytes schweinfurthii) fail to imitate novel actions

Abstract

Background: Social learning research in apes has focused on social learning in the technical (problem solving) domain - an approach that confounds action and physical information. Successful subjects in such studies may have been able to perform target actions not as a result of imitation learning but because they had learnt some technical aspect, for example, copying the movements of an apparatus (i.e., different forms of emulation learning).

Methods: Here we present data on action copying by non-enculturated and untrained chimpanzees when physical information is removed from demonstrations. To date, only one such study (on gesture copying in a begging context) has been conducted--with negative results. Here we have improved this methodology and have also added non-begging test situations (a possible confound of the earlier study). Both familiar and novel actions were used as targets. Prior to testing, a trained conspecific demonstrator was rewarded for performing target actions in view of observers. All but one of the tested chimpanzees already failed to copy familiar actions. When retested with a novel target action, also the previously successful subject failed to copy--and he did so across several contexts.

Conclusion: Chimpanzees do not seem to copy novel actions, and only some ever copy familiar ones. Due to our having tested only non-enculturated and untrained chimpanzees, the performance of our test subjects speak more than most other studies of the general (dis-)ability of chimpanzees to copy actions, and especially novel actions.

Figure 1. Picture of the food dispenser apparatus, as seen from the ape area.

The apparatus was composed of three parts: the board (left bottom), the peanut holder (left middle, behind the mesh) as well as the trigger (right middle).

Figure 2. Schematic drawings of the target action presenting; used in Study 1 and 2.

Figure 3. Picture of Baluku’s performance of the target action (i.e., presenting) in Study 1.

Figure 4. Schematic drawings of the target action chimpanzee praying; used in Study 3, 4 and 5.