On the Nature and Evolution of Imitation in the Animal Kingdom: Reappraisal of a Century of Research

Systematic research on imitation has been pursued for over a century, but methods and conclusions generated in this time have come under strong attack in recent years. Among the most influential ideas have been several that date back to the beginnings of the field in the nineteenth century. In the present article, four of these are distinguished and their consequences and reappraisal in the present century are examined. First, despite early recognition of varieties of imitation, distinctions now made between a greater number of processes by which one animal can come to act like another mean that many conclusions drawn in the first half of this century require revision. Second (and closely related to these theoretical distinctions), experimental paradigms developed in the nineteenth century have been adhered to for much of the present one; only relatively recently have techniques been invented that can adequately distinguish imitation from a range of imitative-like processes. This is important because the latter have important social and cognitive implications in their own right. Third, early assumptions about phylogenetic differences in imitative ability-particularly the superiority of primates-have been reinforced by both observational and experimental studies for much of the present century. Results obtained in recent studies have combined with reappraisal of earlier ones to question these phylogenetic differences. We argue that imitation is as yet unproved in monkeys, whereas chimpanzees (and possibly other apes) share with humans an imitative capacity consistent with other aspects of social cognition examined in recent research. Fourth, it was early argued that auditory-vocal imitation (characteristic of many birds) is distinct from visual imitation (shown by mammals). We use recent research findings to suggest why visual imitation may exert greater computational demands, but also review new studies suggesting that a dichotomy between the vocal imitation of birds and the visual imitation of encephalized mammals is too simplistic to accommodate all the phenomena.