The possible role of field independence/dependence on developmental sex differences in general intelligence

Real-life outcomes for men and women suggest the existence of cognitive sex differences, but the evidence for a sex difference in general intelligence is equivocal. Here, we examine the role of spatial ability for IQ test performance, in light of the developmental hypothesis that male performance increases more than female across adolescence. Using longitudinal data from Block and Block data set on the Wechsler scales and the rod-and-frame test (RFT) for ages 4 (N = 108), 11 (N = 101), and 18 years (N = 100), we find that males' performance becomes greater than females' with age, both on IQ and the RFT. At 18 years of age, males' mean IQ and RFT score was 116.4 and 4.05 (lower scores representing less error), as compared to111.5 and 7.85 for females. Importantly, we found that the RFT mediates the sex difference in IQ, and that the factor loadings of the RFT on the g factor increases with age, from −0.06 at age 4 to −0.52 at 11 and −0.67 at age 18. In conclusion, g becomes more integrative of spatial ability across time and this finding may explain sex differences in g after puberty and potentially has interesting implications for the understanding of the development of intelligence. One important direction for future research is to incorporate biologically based pubertal neural changes into our understanding of developmental sex differences in intelligence.