Attempts to identify the point at which prelinguistic vocalizations are used by infants as a means of communication. A significant relationship between Piagetian causal developmental level and the occurrence of intentional vocalizations was found in a study of 46 infants with a mean age of 10.7 months. (JMB)

Two cognitive tasks of physical uncertainty were used to assign 56 subjects (aged 5 to 17 years) to one of three cognitive stages. Two tests for comprehension of speaker uncertainty were then administered to all participants. Results were interpreted as showing that development of cognitive stages is structurally related to comprehension of speech…

Two experiments tracked infants' eye movements to examine use of word-initial information to understand fluent speech. Results indicated that 21- and 18-month-olds recognized partial words as quickly and reliably as whole words. Infants' productive vocabulary and reaction time were related to word recognition accuracy. Results show that…

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)