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We evaluated over 200 participants semiannually from 12 to 48 months of age on measures of intellectual (Bayley Scales, Stanford-Binet Scale) and verbal (MacArthur-Bates Inventory, Peabody Picture Vocabulary Test) status. Structural equation modeling and hierarchical linear (growth curve) analyses were applied to address the nature of development and individual differences during this time. Structural analyses showed a strong and robust simplex model from infancy to the preschool period, with no evidence of qualitative reorganizations or discontinuities. Growth-curve modeling revealed significant associations between level factors across the early and later measures of cognition, providing further evidence of continuity; the growth trajectory from the Bayley through 24 months predicted growth in a nonverbal factor, but not in a verbal factor. Altogether, the findings reveal continuous and stable development in intellectual function from late infancy through the preschool years. Additionally, the high level of continuity demonstrated across these ages was observed to be largely independent of growth in vocabulary. (Contains 2 figures and 3 tables.)

Young infants have repeatedly been shown to be slower than older infants to shift fixation from a midline stimulus to a peripheral stimulus. This is generally thought to reflect maturation of the neural substrates that mediate the disengagement of attention, but this developmental difference may also be attributable to young infants' slower processing of the midline stimulus. This possibility was tested with 3- and 7-month-old infants in 2 experiments in which the degree of familiarity of the midline stimulus was manipulated across repeated trials. The results of these experiments demonstrated that the processing of midline content does affect infants' ocular latencies to a peripheral stimulus but that developmental differences in such processing do not account for developmental differences in disengagement seen across the 1st year.

A longitudinal sample of 226 infants were tested monthly on habituation and novelty preference tasks, augmented with simultaneous heart rate recording from 3 to 9 months of age. Infants were then administered the Bayley Scales of Infant Development II (BSID) and MacArthur Communicative Development Inventory (MCDI) at 12, 18, and 24 months. Prior findings regarding the decline in look duration with age were replicated. Age-based factors were extracted from the monthly assessments, an early attention factor from 3 to 6 months and a late attention factor from 7 to 9 months. A novelty preference factor, which grouped recognition performance at 4 and 6 months of age, was also derived. The late attention factor correlated negatively with a factor score derived from the BSID mental index, and the novelty preference aggregate was correlated positively with a factor score derived from the MCDI production scores. Two clusters of infants were derived based on the developmental course of change from the early attention to late attention look duration aggregates: One cluster (n= 150) decreased strongly, and another (n= 50) increased. Infants belonging to these clusters subsequently differed on both the BSID and MCDI outcomes, with the former cluster showing distinct advantages that increased as the outcome assessments progressed from 12 to 24 months of age. This finding was bolstered by subsequent analyses of data from infants who completed all tests run from 3 to 9 months. The results of this study suggest that the developmental course of attention during infancy is an important clue to cognitive and language outcomes in early childhood. (Contains 11 tables, 5 footnotes and 5 figures.)

Young infants have repeatedly been shown to be slower than older infants to shift fixation from a midline stimulus to a peripheral stimulus. This is generally thought to reflect maturation of the neural substrates that mediate the disengagement of attention, but this developmental difference may also be attributable to young infants' slower processing of the midline stimulus. This possibility was tested with 3- and 7-month-old infants in 2 experiments in which the degree of familiarity of the midline stimulus was manipulated across repeated trials. The results of these experiments demonstrated that the processing of midline content does affect infants' ocular latencies to a peripheral stimulus but that developmental differences in such processing do not account for developmental differences in disengagement seen across the 1st year. Keywords: ocular latencies, information processing, disengagement, attention, infants