Infant perception of the relative relevance of different manual actions

Abstract

Six- to nine-month-olds have been found to perceive manual actions as object-directed. They apply this interpretation even to unfamiliar, non-purposeful-looking movements if these produce salient object-directed effects. We investigated whether infants engage in a differential weighting of movement – effect instances, perceiving some instances as more “meaningful” than others. Thus, infants might preferentially encode movement – effect couplings involving prehensile movements, in contrast to couplings involving movements like touching, even if these produce salient effects. Seven- and nine-month-olds were habituated to two movement – effect couplings in close succession, a grasp/lift event and a touch/overthrow event, each directed at one of two objects, respectively. Subsequently, one object was exchanged, and looking time to the same events, with one of them involving the novel object, was measured. Preferential encoding of the prehensile action should result in a stronger dishabituation to a change in the object involved in this action (primary object) than to a change in the object involved in the touch/overthrow event (secondary object). Nine-month-olds looked significantly longer at a primary-object change. Seven-month-olds tended to look longer at the secondary-object change. This suggests that a preferential encoding of “meaningful” as compared to salient events develops between 7 and 9 months.

Acknowledgments

We would like to thank Knut Drewing for many helpful comments on the manuscript. Further, we thank the research team for helping to conduct the experiments, especially Dominique Rompf and Katinka Bloemer. Finally, we thank the parents and infants who so generously donated their time and energy to participate in this study.