Spatial-mechanical reasoning skills versus mathematics self-confidence as mediators of gender differences on mathematics subtests using cross-national gender-based items

For 187 Grade 8 students, we compared spatial-mechanical skills with mathematics self-confidence as mediators of gender differences in mathematics. Using items showing the largest male and female advantage, respectively, on the Third International Mathematics and Science Study (TIMSS) U.S. data, we created mathematics Male and Female subtests from items on the 8th-grade TIMSS. Using path-analytic techniques, we decomposed a significant gender/mathematics correlation, favoring males, on the MISS-Male subtest into direct and indirect effects. We found only indirect effects. A spatial-mechanical composite accounted for 74% of the total indirect effects, whereas mathematics self-confidence accounted for 26%. By 8th grade, girls' relatively poorer spatial-mechanical skills contribute to lower scores on types of mathematics at which boys typically excel.