A model's natural group membership affects over-imitation in 6-year-olds.

The phenomenon of "over-imitation"-the copying of causally irrelevant actions-has influenced research of the past decade. Yet, the mechanisms underlying and factors affecting over-imitation are still under debate. This study aimed to contribute to this debate by investigating the role of the model's natural group membership in children's tendency to imitate irrelevant actions using a two-phase design. In Phase 1, 6-year-olds (N = 64) observed either an in-group model or an out-group model presenting a sequence of irrelevant actions, with only the last action bringing about the goal (target action) and retrieving a token. In Phase 2, the alternative model-the one that children had not seen in Phase 1-retrieved the token by performing the target action only. After the presentation in each phase, children were given the chance to retrieve the token themselves. Results indicated that children imitated the irrelevant actions to comparable levels from both models in Phase 1. In Phase 2, in contrast, over-imitation declined in children who observed the in-group model being successful with the target action only but not in children who observed the out-group model do so. Thus, children adapted their imitative behavior after observing the model of their own cultural group demonstrating a more efficient strategy. These findings speak for an integration of both social and instrumental accounts to explain the phenomenon of over-imitation.