Is early differentiation of human behavior a precursor to the 1-year-olds understanding of intentional action? Comment on Legerstee, Barna, and DiAdamo (2000)

In a recent issue of Developmental Psychology, M. Legerstee, J. Barna, and C. DiAdamo (2000) reported a study showing that 6-month-olds expect people to tally to persons rather than to inanimate objects and to manipulate inan imates rather than persons. They interpreted this ability as a "precursor" to later understanding of intentionality. The present article takes issue w ith the authors' 2 different levels of interpretation that contradict each other and raise problems in their own right. It is suggested that M. Legers tee et al.'s finding is most parsimoniously explained by associative teamin g and may not constitute a precursor to later understanding of intentionali ty in any well-defined sense of the term. The present article argues for th e importance of differentiating between associative and inferential process es and reviews evidence that the understanding,of goal-directed action arou nd 9 months of age involves principle-based inferences.