Growth parameters and attention to faces at 4 to 6 months of age

Duration of attention to faces and response decrement were studied in 57 full-term infants between 15.1 and 28.5 weeks of age during a health maintenance clinic visit. Six measures of growth, obtained from the medical record, included weight, length, and head circumference at birth, and weight, length, and head circumference at the time of the clinic visit. Correlation analysis revealed that longer average initial fixation time was associated with male sex, shorter birth length, and larger ponderal index. Multiple regression analysis indicated that together these three variables accounted for 17% of the variance in average initial fixation time (p <0.05). Length at the time of the health maintenance visit and male sex also were associated with longer average initial fixation time and, together, accounted for 13% of the variance (p <0.05). Response decrement was larger in children with larger head circumference at birth, in girls, and in infants with a larger ponderal index at birth. Together, these three variables accounted for 27% of the variance (p <0.001). Results suggest that more efficient processing of visual information may be related to neurophysiological maturity at term, and raises the possibility that neurophysiological maturity may account for a substantial portion of the correlation between attention behavior and later intelligence.