Task-Specific Dynamics and the Study of Perception and Action: A reaction to von Hofsten (1989)

In a recent discussion of motor development, von Hofsten (1989) distinguished two approaches which he called the perception-action and dynamic systems ap- proaches, respectively. In this reaction, we suggest that the proposed distinction is inappropriate. We argue that research on perception and action in terms of task-specific dynamics is uniquely suited to the characterization of problems inherent to the coupling of perception and action. The problems discussed include the problem of stability and transitions in behavior; the problem of perceptual information about physical properties of the action system; and the role of the brain in the context of the degrees of freedom problem, the problem of multiple scales of analysis, and the heterogeneity of the components of the human action system including the brain.