VECTOR SUMMATION IN YOUNG INFANTS

Immaturities in cortical visual processing make the retinocollicular p athway dominant in young infants' saccadic control. The superior colli culus appears to transform retinal position into saccadic commands by the summation or averaging of movement vectors associated with deep la yer neurons. We explored the extent to which infants 2, 4, and 6 month s of age would make saccades equivalent to the sum of individual retin al vectors of two simultaneous visual targets. Consistent with predict ions that increasing cortical influence over saccade generation would diminish the prevalence of vector sum saccades, we observed that the m ean proportions of these responses declined as the age of subjects tes ted increased.