Study looks at pigtailed macaque in the context of visual recognition problems adapted from a standardized test developed for use with human infants. Results demonstrate that the low-risk group easily differentiated novel from previously seen targets; the high-risk group gave no evidence of recognition. (Author/RWB)

Four-month-old rhesus monkeys were removed from their social group under three different conditions of perceptual isolation from their mothers and peers. Infant behavior was recorded and blood samples were obtained for analysis of plasma cortisol. Infants never showed signs of depression; their responses following separation were seen as attempts…