Motion coherence in infants.

Two perpendicular square-wave gratings (i.e. plaids) were used to investigate motion coherence in 1-, 2- and 3-month-old infants. The direction of motion of the stimulus was judged by an adult observer, on the basis of the induced optokinetic nystagmus (OKN) in an eight-alternative eye movement voting paradigm. Infants as young as 1 month of age demonstrated OKN in the direction consistent with motion coherence. There was no significant difference among the performances of 1-, 2- or 3-month-old infants. However, the percentage of trials on which infants demonstrated OKN in the coherence direction was less than that obtained from adults tested with the same paradigm. Movshon, Adelson, Gizzi and Newsome (1985) have suggested that the cohered motion of a complex pattern may be processed after the orientation of the components of the pattern, perhaps in the middle temporal area of the visual cortex (MT). The present results suggest that either young infants and adults process the motion of complex patterns similarly or that the OKN consistent with the direction of motion coherence observed in infants involves subcortical nonoriented visual centers rather than the higher level process which is presumed to occur in adults.