Infant predictors of preschool and adult IQ: a study of infant twins and their parents

Recent infant research in attention and information processing has shown that individual differences in infancy can predict later intelligence quotient (IQ). To assess the best predictors of IQ later on, healthy same-sex infant twins (208 pairs) and their parents were studied. Parents were given an IQ test and a battery of other tests assessing cognitive ability, and twins were given tests of visual expectations. Twins' IQs were then retested at one, two and three years of age. All analyses were repeated separately for boys and girls. Girls scored significantly higher on IQ scores at ages one, two and three years. This finding is attributed to early gender differences in temperament. Average scores of individual twin-sets (midtwin scores) for all the early study measures were correlated with midtwin IQ scores assessed at ages one, two and three years. Overall, results contribute to the body of evidence pointing to stability in intellectual development from infancy on. The best predictors of later IQ, and of midparent IQ scores were found to be: (1) the visual expectations test administered at eight months; (2) Fagan's Test of Infant Intelligence, which measures infant novelty preference and recognition memory; and, (3) testing at nine-months with the Bayley's Infant Behavior Record, which assesses social orientation, cooperativeness, fearfulness, and level of responsiveness. (Consumer Summary produced by Reliance Medical Information, Inc.)