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.

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This study investigates the association between home computer experience and cognitive development among preschool children in inner-city Head Start programs. Approximately 200 children enrolled in four Head Start centers in Detroit, Michigan were recruited to participate in this study. Data was collected from parents regarding the children's experience with computers in the home environment, including their access to a computer, the amount of time spent on the computer, and types of programs used on the computer. Each child was assessed using the McCarthy Scales of Children's Abilities (MSCA) and the Boehm Test of Basic Concepts, Third Edition Preschool (Boehm-3). Results suggest that using a computer is positively correlated with some aspects of cognitive development. After controlling for parent's education and household income, children who had access to a computer in their home had significantly higher scores of the Verbal, Perceptual-Performance, and General Cognitive scales of the MSCA. Furthermore, frequency of children's computer use was related to scores on the Boehm-3. These results suggest that early computer use at home may be a positive influence in young children's cognitive development. 97

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