Abstract

Infant visual performance is much worse than that of adults. According to one account,¹ the striking morphological immaturity of infant foveal cones contributes directly to the poor vision of infants. This explanation depends on the assumption that infants use their immature foveal cones to control visual performance. In another account,² immaturity of the foveal cones contributes indirectly to poor visual performance by forcing the infant to use the (relatively mature) extrafoveal retina to do tasks the adult does foveally. To decide between these two views, I used morphological data on human and macaque infants to estimate the amount of light absorbed by the foveal and extrafoveal cones. The fraction of the retinal surface over which photons may be absorbed was constant with age in the macaque extrafoveal retina, and equal to the fraction for human adults. All other data were from humans.

© 1992 Optical Society of America