Infants' Perception of Biomechanical Motions: Intrinsic Image and Knowledge-Based Constraints
Bennett I. Bertenthal
University of Virginia
One of the most notable contributions of the infant research literature over the past decade has been its revolutionary impact on our thinking about perceptual and cognitive development ( J. M. Mandler, 1990). No longer can we assume that basic concepts about number, people, causality, and so forth must await the development of concrete operational thinking ( Piaget, 1970), or, for that matter, even preoperational thinking. Much of the recent research points to the conclusion that the infant comes into the world with a set of fundamental constraints on, or processing heuristics relating to, how information can be organized or extracted ( Keil, 1981; Rozin, 1976).
The presence of constraints on information extraction is nowhere better demonstrated than in recent studies on infants' sensitivity to motion-carried information. During the past few years, my colleagues and I have been centrally concerned with this issue while studying infants' sensitivity to biomechanical motions. These are the motions that correspond to the movements of a person, and are typically depicted by an array of point-lights moving as if attached to the major joints and head of a person walking.
Biomechanical displays provide a unique opportunity for studying the development of structure from motion. In contrast to most displays shown to infants, these displays depict objects that are functionally important and frequently seen. Moreover, the jointed motions that are depicted in these displays are morphologically equivalent to some of the same motions that are produced by infants. Thus, there is the rather unusual opportunity for "knowledge by acquaintance" in the perception of biomechanical motions by infants.