Visual and social responses in infant rhesus monkeys.

This paper reviews a program of research on the development of visual functions and social responsiveness in infant rhesus monkeys (Macaca mulatta). One study involved a clinical examination of simple visual reflexes (e.g., orienting) and more complex visuo-motor responses (e.g., gaze aversion and reaching). Such responses changed dramatically over the first two weeks of life. Two other studies used infrared corneal-reflection techniques to monitor visual scanning: One determined when infant monkeys become sensitive to the direction of aconspecific's gaza. By week three, rhesus monkeys scanned faces looking back at them less than faces looking away. The other study investigated whether, like human infants, Young monkeys shift from scanning external contours of a pattern to scanning internal details. Unlike human infants, however, young monkeys shifted from proportionally more internal scanning to proportionally more external scanning. As a whole, the studies demonstrated rapid development of visual functions and visually cued social responses and raised important questions for future research.