Four-year-old children exposed prenatalry to porychlorinated biphenyls (PCBs), an environmental toxin, were assessed on three tasks-two designed to evaluate cognitive processing efficiency and one to evaluate sustained attention. When compared with standardized IQ tests, these tasks provided greater specificity in identifying cognitive deficits. Adapted for 4-year-old children in the present study, these paradigms demonstrated moderate levels of test-retest reliability. Prenatal exposure to PCBs was associated with less efficient visual discrimination processing and more errors in short-term memory scanning but not with sustained attention. Although much larger quantities of these contaminants are transferred postnatally via breastfeeding than prenatally across the placenta, postnatal exposure was unrelated to cognitive performance. The data link intrauterine PCB exposure to two dimensions of cognitive functioning fundamental to learning.

Visual expectation was assessed in 103 black 6.5-month-olds using Haith, Hazan, and Goodman's paradigm and related to performance on standard developmental assessments and tests of information processing skill. As expected, percent anticipations was higher and RT lower than in 3.0-month-olds previously tested. Split-half and left-right correlations for the RT measures were moderate and similar to those previously reported, as was split-half reliability for percent anticipations. The 2 RT measures were related to fixation duration on both visual recognition memory (VRM) and cross-modal transfer, suggesting moderate cross-task and cross-age consistency in processing speed. Percent anticipations and baseline RT each contributed independently to the prediction of VRM novelty preference. Data from a factor analysis suggested 3 dimensions of cognitive function: processing speed, developmental level, and memory/attention. These findings suggest that the visual expectation paradigm provides a reliable new approach for assessing cognitive processing efficiency and attention during infancy.

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1995) applied synchronous and time-series regression techniques to observational data to detect effects of recasted error correction on children's emerging grammar. Results showed that recasts did not facilitate learning but actually impeded it. In this study, a format modeling procedure was used to generate similar time series with known, underlying learning relations. The regression procedures used by Morgan et al. could not discriminate between the data generated by models in which recasts (a) totally determined grammatical learning, (b) supplemented other learning, (c) inhibited learning, or (d) had nothing to do with grammatical learning. These modeling results and review of statistical and conceptual problems indicate that Morgan et al.'s analyses (short term as well as long term) are umnterpretable as regards the role of recasts or any form of negative evidence in children's syntactic acquisition. However, their descriptive data confirm many prior reports on when parents use recasts and raise interesting questions about possible bidirectional influences between adult recasts of a syntactic structure and the acquisition of that structure.

Visual expectation was assessed in 103 black 6.5-month-olds using Haith, Hazan, and Goodman's paradigm and related to performance on standard developmental assessments and tests of information processing skill. As expected, percent anticipations was higher and RT lower than in 3.0-month-olds previously tested. Split-half and left-right correlations for the RT measures were moderate and similar to those previously reported, as was split-half reliability for percent anticipations. The 2 RT measures were related to fixation duration on both visual recognition memory (VRM) and cross-modal transfer, suggesting moderate cross-task and cross-age consistency in processing speed. Percent anticipations and baseline RT each contributed independently to the prediction of VRM novelty preference. Data from a factor analysis suggested 3 dimensions of cognitive function: processing speed, developmental level, and memory/attention. These findings suggest that the visual expectation paradigm provides a reliable new approach for assessing cognitive processing efficiency and attention during infancy.