Sex differences in processing speed: Developmental effects in males and females

The purpose of this study was to compare the cognitive abilities and selected achievement performance of females and males across the lifespan on standardization samples of broad cognitive abilities in 1987 participants (1102 females, 885 males) from the WJ III, 4253 participants (2014 males, 2239 females) from the WJ-R, and 4225 participants (1964 males and 2261 females) from the WJ-77. Preschool through adult cohorts were included in the analyses. The results indicated that males scored significantly lower on estimates of Gs (processing speed) in all three normative samples, with the largest difference evident in adolescent subgroups. A secondary finding was significantly higher scores for males on estimates of comprehension knowledge (Gc) in all three samples. Follow-up analyses of the achievement tests also indicated lower performance for males on speeded tests such as reading fluency and writing fluency. There was a high degree of concordance across tests and no sex difference was observed in overall estimates of general intellectual ability (GIA) on the WJ III. The educational implications of these findings are discussed with an emphasis on the adolescent (high school) cohort.