Development of vision in infant primates.

A systematic programme of research on the development of spatial vision (acuity and contrast-sensitivity functions or CSFs) in human and macaque monkey infants (Macaca nemestrina) is described. A forced-choice preferential looking technique has been used to follow the development of acuity in both species. Acuity development is similar across the two species, with the infant monkeys progressing about four times faster than the human infants. Operant conditioning has been used to trace the development of CSFs in monkey infants. Changes in the shape of the CSF are shown for at least 20 postnatal weeks in the macaque infants. Strabismic and meridional amblyopias have also been mimicked in infant monkeys, and the time course of development of strabismic amblyopia in a monkey is described. It is argued that closely parallel behavioural studies, carried out on both species, are important in establishing the monkey as a model for human visual development.