Infants' Sensitivity to Motion-Carried Information for Depth and Object Properties
Martha E. Arterberry Gettysburg College
Lincoln G. Craton Trinity University
Albert Yonas University of Minnesota
Since the early 1980s, research on infants' sensitivity to motion-carried information has typically reported early competence. For example, Yonas and his colleagues ( Yonas, Pettersen, & Lockman, 1979) and Nanez ( 1988) found that infants between 3 weeks and 3 months of age respond to optical expansion information specifying impending collision. Kellman and his colleagues ( Kellman & Spelke, 1983; Kellman, Spelke, & Short, 1986) found that 4-month-old infants perceive the unity of a partially occluded object only when the visible ends of the object undergo a rigid translation. Moreover, several researchers have found evidence that 4-month-olds perceive the three-dimensional shape of moving objects ( Arterberry & Yonas, 1988; Kellman, 1984; Kellman & Short, 1987; Owsley, 1983; Yonas, Arterberry, & Granrud, 1987a), but infants provide no evidence of perceiving the three-dimensional shape when presented with successive static views of a rotating object ( Kellman, 1984).
These findings have led to a widespread view that motion-carried information is the primary information used by young infants. Sensitivity to some types of motion-carried information is present before sensitivity to binocular disparity (which emerges around 4 months of age) and pictorial depth cues (which emerge between 5 and 7 months of age). Thus, before 4 months it is likely that infants' spatial perception is based on motion cues ( Yonas & Granrud, 1984; see Yonas , Arterberry, & Granrud, 1987b for a review). In addition, Kellman's work ( Kellman, 1984; Kellman & Spelke, 1983) suggests that motion information provides for the perception of three-dimensional object shape and object unity before static cues. These findings are consistent with a Gibsonian ( 1950, 1966,