Comments on Thelen and Ulrich's monograph in this issue. Examines theoretical and empirical sections and findings, concluding that the authors have taken a major step forward by introducing the dynamic systems perspective to the study of behavioral coordination in infants, thus opening the way for experimental investigation of phenomena that could…

Differences in 3-month-old infants' vocal responsiveness to vocal-visual stimulation by mothers and strangers has been shown to be related to performance on both the Stanford-Binet at 3 years of age and the Illinois Test of Psycholinguistics at 5 years of age. The present retesting of 12 of the original 14 normal, first-born male subjects, now 12…