The notion of internalization put forth by Roger Shepard continues to be appealing and challenging. He suggests that we have internalized, during our evolutionary development, environmental regularities, or constraints. Internalization solves one of the hardest problems of perceptual psychology: the underspecification problem. That is the problem of how well-defined perceptual experience is generated from the often ambiguous and incomplete sensory stimulation. Yet, the notion of internalization creates new problems that may outweigh the solution of the underspecification problem. To support this (...) claim, I first examine the concept of internalization, breaking it down into several distinct interpretations. These range from well-resolved dynamic regularities to ill-resolved statistical regularities. As a function of the interpretation the researcher selects, an empirical test of the internalization hypothesis may be straightforward or it may become virtually impossible. I then attempt to cover the range of interpretations by drawing on examples from different domains of visual event perception. Unfortunately, the experimental tests regarding most candidate regularities, such as gravitational acceleration, fail to support the concept of internalization. This suggests that narrow interpretations of the concept should be given up in favor of more abstract interpretations. However, the latter are not easily amenable to empirical testing. There is nonetheless a way to test these abstract interpretations by contrasting internalization with the opposite concept: externalization of body dynamics. I summarize evidence for such a projection of body constraints onto external objects. Based on the combined evidence of well-resolved and ill- resolved regularities, the value of the notion of internalization has to be reassessed. Key Words: event perception; evolution; internalization. (shrink)

Empirical research on the perception of physical events is rarely designed to test a particular theory. The research often fails to be embedded in a larger theoretical context or it is carried out with the implicit goal to support a particular theoretical approach. I argue that this is not very productive. While three theories are relevant for our understanding of events, their limits have rarely been addressed. I expose these limits. The three theories or approaches are direct or ecological perception, (...) inference theory, and the concept of internalization. I demonstrate that all three fail empirically and/or theoretically with respect to explaining the perception of events. They fail because they adhere to simplistic stationary views or because they remain too vague. An adequate theory of event perception has to include three factors at the level of the explanans, namely the stimulus, the purpose of the action to which the percept belongs, and the appraisal of this action's success. Examples from the domains of arrival-time judgment and perception of events involving classical mechanics are used to support the claims. I suggest that a new pragmatic theory of event perception ought to modify and to incorporate the three concepts of affordances, thought-like processes, and evolutionary principles. (shrink)

We share the authors' general approach to the study of perception and action, but rather than singling out a particular level of “late perceptual” and “early motor” processing for sensorimotor interactions, we argue that these can arise at multiple levels during action preparation and execution. Recent data on action-perception transfer are used to illustrate this perspective.