 The results indicate that vocalizations did significantly correlate with girls’ later intelligence, increasingly so with age, and more highly with verbal then performance scores.In 1983, 25 low-risk mother-infant pairs participated in a research project to predict the performance of 21 month olds on the Mental Scale of the Bayley Scale of Infant Development (BSID-1) from characteristics of infants and mothers.Questionnaires given assessed maternal responsive attitude during the prenatal period, the Neonatal Behavioral Assessment Scale was administered at 5 and 10 days, and mothers and infants were observed together at 3 months.