Infant antecedents of cognitive functioning: a longitudinal study.

A follow-up investigation of 35 boys and 33 girls 10 years old who had been assessed originally at 4, 8, 13, and 27 months old did not reveal strong relations between infant variables such as attentiveness, vocal excitability, irritability or activity, on the one hand, and reflection-implusivity, intelligence quotient, or reading ability at age 10. A suggestive relation was found between assimilative smiling during infancy and a reflective attitude on the Matching Familiar Figures Test and between a slow tempo of play during infancy and longer response time on a specially constructed Embedded Figures Test at age 10. Although attentiveness during infancy predicted IQ and reading ability at age 10, both infancy and childhood variables were positively correlated with social class, suggesting that experiences associated with the social class of the parents, rather than particular infant qualities, were the more important predictors of the cognitive variables at age 10. Children with high EMG levels from the flexor forearm tended to be slightly more impulsive at age 10 and less attentive at 27 months, even when the effect of social class was removed.