Behavioral Development in a Cynomolgus Monkey Infant with Congenital Cataracts

Abstract

Vision is very important for primates in their physical and social lives. The present investigation was conducted to clarify characteristics of behavioral development of a cynomolgus monkey (Macaca fascicularis) infant with congenital cataracts and to study the infant's interactions with its mother and other cage mates. Subjects were five pairs of mothers and infants, includung a pair in which the infant had congenital cataracts. Observations were made once or twice a week for 15 minutes each. Observations were made of interactions between the congenital cataract infant and its mother for the infant's first 18 weeks of life. At eight months the infant was separated from its mother and placed with a peer until it was two and a half years old. It was then housed with a youger infant.

The infant with congenital cataracts showed slight retardation in behavioral development, but, on the whole, its locomotion and filial behavior developed normally. The infant did not develop any stereotyped behaviors which might have been caused by social isolation. However, the animal did show maladjustment in interaction with a peer. It appears that a severe visual defect does not produce problems in the simple mother-infant situation. On the other hand, it may have an important negative effect in more complex peer interactions.