The development of early vocalizations was investigated with 13 infants who had Down's syndrome and 27 infants developing normally, at bimonthly intervals from 4 to 18 months of age. Both groups demonstrated increased production of mature syllables over time as well as large variations in vocal development, both within and across groups and across…

Examined the relationship between infants' early verbal imitation, when the ability to copy behaviors first emerges, and their lexical development during the second year of life. Twenty infants were examined longitudinally at ages 10, 13, 17, and 21 months. Suggests that infants' early imitation of words not in their repertoires predicts and may…

Investigated developmental change in symbolic representational ability by examining infants' imitation of vocalizations, words, visible motor actions, and nonvisible motor behaviors at ages 10, 13, 17, and 21 months. Results revealed a pattern of increasing imitation, supporting the view that a domain-independent representational capacity develops…

Tested a normally developing child several times between 16 and 27 months of age for his ability to derive the relations between stimuli. Found that the child derived "mutual entailment" relations and showed "nonverbal exclusion" as early as 17 months. "Combinatorial entailment" relations and "verbal…

This research bulletin includes reports of research in progress or recently completed from September 1971 through February 1972. Each entry includes information concerning the investigator, purpose, subjects, methods, duration, cooperating groups, and findings (if available). The reports are listed under several topical headings: (1) Long-Term…