Corter, C. M. (1976). The nature of the mother's absence and the infant's response to brief separations. Developmental Psychology, 12(5), 428-434.
http://dx.doi.org/10.1037/0012-1649.12.5.428
During a brief play period away from the mother, the responses of 40 10-mo-old infants were observed as a function of 2 factors: first, whether the mother or the infant initiated the separation and, second, whether the mother was visible during the separation. When the mother was visible in another room the infant was content to stay and play longer than when she was out of sight. Whether the infant left the mother or was left by her had no effects. In all conditions, distress away from the mother was rare. Results show that separation distress is not inevitable and suggest that manipulations of separation situations may elucidate the interplay between exploratory and attachment responses. (20 ref) (PsycINFO Database Record (c) 2016 APA, all rights reserved)