"Coordination between infant and adult is thought to be essential to development... The research in this Monograph -- grounded in a dyadic systems perspective and relational psychoanalysis -- addresses the issue of vocal coordination. The research employs an automated apparatus to examine the micro-second vocal coordinations of 4-month old infants with their mothers and with strangers. These coordinations are then used to predict infant attachment and cognition at 12 months. The results demonstrate that coordination is related to the contexts of partner (mother/stranger), site (home/lab) and outcome (attachment/cognition)... a midrange of coordination was found to be optimal for attachment... for cognition a high degree of coordination between stranger and infant was optimal"--Back cover.