'Over-imitation': A review and appraisal of a decade of research

After seeing an action sequence children and adults tend to copy causally relevant and, more strikingly, even perceivably unnecessary actions in relation to the given goal. This phenomenon, termed over-imitation, has inspired much empirical research in the past decade as well as lively theoretical debate on its cognitive underpinnings and putative role in the transmission of cultural knowledge. Here, we offer a comprehensive review of the existing literature to date, accompanied by a table including concise information on 54 published studies testing over-imitation in different species, age groups and cultures. We highlight methodological issues related to task and context that influence over-imitation rates and that should be carefully considered in study designs. We discuss the cognitive and motivational processes underlying and contributing to over imitation, including normative action parsing, causal reasoning, motives of affiliation and social learning as well as their complex interplay. We conclude that despite the apparent irrationality of over-imitation behavior, recent studies have shown that its performance depends on the specific task, modeled actions and context variables, suggesting that over-imitation should be conceptualized as a contextually flexible and, in fact, a normally highly functional phenomenon.