Sex differences in spatial and mechanical tilt: Support for investment theories

Tilt refers to a pattern of specific abilities and is based on within subject differences in two abilities (spatial and academic), yielding relative strength in one ability (spatial) and weakness in another ability (academic). The current study examined sex differences in spatial and mechanical tilt. Tilt was measured using the Armed Services Vocational Aptitude Battery in the National Longitudinal Survey of Youth. Tilt was based on spatial and mechanical abilities contrasted with academic abilities (math or verbal), producing spatial and mechanical tilt (spatial/mechanical > academic) and academic tilt (academic > spatial/mechanical). For males and females, spatial and mechanical tilt correlated negatively with verbal and math scores on college tests (SAT, ACT, PSAT), indicating that spatial and mechanical tilt predicted low scores on the college tests. In addition, for males and females, spatial and mechanical tilt predicted jobs and college majors in science, technology, engineering, and math (STEM), with stronger effects for spatial and mechanical tilt contrasted with verbal ability. Although levels of mechanical tilt were higher for males, levels of spatial tilt showed no sex differences, a pattern that could be attributed to the spatial ability measured (visualization). In addition, no consistent sex differences in tilt relations with diverse criteria (tests, jobs, majors) were found. The results support investment theories and research on sex differences in vocational preferences for people versus things. Such theories assume that males prefer working with things and machines, boosting mechanical tilt, whereas females prefer working with people and in (non-technical) humanities fields, boosting academic tilt. Future research should consider tilt patterns in other developmental periods and examine whether tilt varies with ability level, as predicted by differentiation theories.