Attachment, Loss, and Depression *

SUMMARY The influence of 10 days of maternal separation on behavior and physiology was studied in 8 social group living pigtailed macaque ( M. nemestrina )monkey infants. Maternal separation was accompanied by behavioral changes' included slowing of movement, decreases in play, increases in oral behaviors, and assumption of a characteristic slouched posture and sad facial expression. Physiological changes included decreases in heart rate and body temperature, sleep disturbances that were most pronounced in the Awake and REM sleep systems, and changes in EEG alpha power‐spectra. Individual variability in the behavioral and physiological response to maternal separation was marked, and showed only a minimal correlation with measures of early behavioral development and the early mother‐infant interaction. Some physiological changes appeared to lie relatively long lasting. The data demonstrate that the disruption of an attachment bond may be accompanied by pronounced physiological changes suggestive of d general impairment of autonomic homeostatic regulatory processes. The findings have important implications for our understanding of the Pathophysiology of grief, and the physiological concomitants of. separation, loss, and depression in children.