Examines whether three-month-old infants can detect variations within the single expression category of smiling and whether individual differences in infants' sensitivities are related to identifiable mother or infant behaviors. (HOD)

Addressing methodological limitations, Study One compared parent-child interactions of normal and language-delayed children; Study Two investigated whether mothers adjust the length of their utterances to the child's ability to comprehend or to produce language; Study Three probed interactional variables associated with variations in the…

Using a longitudinal design, investigates the interactive behaviors of mothers of normal infants and mothers of infants who are known to differ on a host of cognitive, behavioral, and biological parameters. Examines the developmental course of emotional expressivity in these infants. (HOD)