Separation distress and attachment in surrogate-reared squirrel monkeys.

Surrogate-reared infant squirrel monkeys were exposed to various conditions of separation from their surrogate. Infants showed significant increases in plasma levels of cortisol when they were placed in an unfamiliar environment during the separation period. Changes in behavior, but not cortisol, were observed under conditions in which the surrogate was removed and the infant left in the home cage. These results differ from those previously obtained with mother-reared infants. It is concluded that surrogate-reared infant squirrel monkeys do not show the same separation response or attachment to their rearing figure as do mother-reared infants.