Paradoxical decrease of imitation performance with age in children

AbstractWe studied the development of imitation ability in a cohort of 6-11-year-old children (N=174) with specific attention to error types and to their cognitive interpretation. Participants imitated meaningless actions as if they were in front of a mirror (specularly). Actions varied across three levels of complexity (movements of a single limb, of arm and leg of the same body side, or of arm and leg of opposite sides). Overall performance improved with age. Among the most frequent error categories, “side” errors (movement imitated with the left instead of the right limb or vice-versa) paradoxically increased with age (from 9 years), but their sensitivity to complexity decreased with age. Thus, encoding two opposite body sides has high cognitive costs in younger children, and smaller or null costs in older children. We interpreted these results in terms of enhancement of Working Memory (WM) and body knowledge with age. When WM increases, it paradoxically drives older children to apply their superior body knowledge and imitate “anatomically”, producing side errors. Younger children are free from such interference because they still lack the necessary body knowledge and WM capacity. The (fewer) side errors made by younger children would be due to failure to manage the conflict between opposite spatial codes, an effect of limited WM capacity witnessed by their sensitivity to action complexity. In conclusion, this study suggests that anatomical imitation becomes available in children’s cognitive repertoire from age 9, as an effect of increased body knowledge and WM capacity.Research HighlightsThe analysis of error types uncovers/illustrates the role of working memory and body knowledge in imitation.As an effect of little working memory capacity, younger children pay a cognitive cost to encode opposite body sides and make “side errors”.Imitation performance improves with age, but side errors paradoxically increase in frequency due to greater ability to master body knowledge bringing to anatomical imitation.Anatomical imitation is available in childrens’ cognitive repertoire from age 9, as an effect of the development of body knowledge and working memory capacity.