Explored relation between infants' early spontaneous imitation of novel and familiar words and subsequent lexicons in longitudinal sample between 13 and 21 months. Found marked contrasts in quantity and proportions of nouns between reported and observed lexicons. When earlier vocabulary levels were controlled, infants' early replication of novel…

Home movies of eight normal children and eight children later diagnosed as autistic were analyzed based on: (1) Piagetian criteria of sensorimotor development and semiotic functioning, and (2) developmental levels of action competencies. The age range covered was 4 to 42 months of age. The analysis showed that, from the second year of life, timing…