Behavioral and hormonal responses to separation in infant rhesus monkeys and mothers.

Examined the effects of social stimuli on behavioral and physiological responses in 9 infant rhesus monkeys, 8 Ss at 4–6 mo (Exp I) and 7 of the original Ss and an additional S at age 8–10 mo (Exp II). Infants and mothers were removed from the social group and housed as dyads. Following this period, infants were removed and separated under 4 counterbalanced conditions: (a) totally isolated—placed in a holding cage for 24 hrs; (b) mother present, no contact—housed in a single cage in view of their mother, no contact; (c) mother present, contact—similar to above, with mother in proximity to the infant; and (d) peer present—separated but in proximity to a peer. In Exp I, infants rarely vocalized when totally isolated but showed high rates of vocalization in the presence of the mother, both with and without contact. In the mother-present conditions, they failed to show a plasma cortisol response. In contrast, totally isolated infants showed a significant elevation in plasma cortisol. In Exp II, these infants were separated for 3 days under 2 conditions: mother present and totally isolated. Results support and extend the findings of Exp I, indicating that age was not a factor in modulating response to separation. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)