Is early differentiation of human behavior a precursor to the 1-year-old's 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 talk to persons rather than to inanimate objects and to manipulate inanimates rather than persons. They interpreted this ability as a "precursor" to later understanding of intentionality. The present article takes issue with the authors' 2 different levels of interpretation that contradict each other and raise problems in their own right. It is suggested that M. Legerstee et al.'s finding is most parsimoniously explained by associative learning and may not constitute a precursor to later understanding of intentionality in any well-defined sense of the term. The present article argues for the importance of differentiating between associative and inferential processes and reviews evidence that the understanding of goal-directed action around 9 months of age involves principle-based inferences.