Sex Differences in Mathematical and Spatial Ability

Background

Camilla Benbow and Julian Stanley in 1983 created a controversy when they published their findings concerning the top-scoring students in their mathematics talent search, who were disproportionately men. Benbow and Stanley suggested men's superiority in mathematical reasoning as one hypothesis to explain their findings. Indeed, at the top 50 universities, the proportion of full professorships held by women in math-intensive fields (engineering, mathematics, physics, computer sciences, chemistry) ranges between 3 percent and 15 percent. Does this underrepresentation [Page 802]reflect innate differences in some kinds of ability, or are nonability accounts such as culture, differential interests, or discrimination to blame? This entry, based on the past few decades of analyses of sex differences research, explores the issues pertinent to answering these questions.

In 1995, Larry Hedges and Amy Nowell examined six studies, each based on a national probability sample of adolescents and young adults. They found that the cognitive ability distributions for men and women differed substantially among the top and bottom 1, 5, and 10 percent: Men excelled over women in science, math, spatial reasoning, and social studies as well as in various mechanical skills. Women excelled over men in verbal abilities, associative memory performance, and perceptual speed. The means for men and women were usually similar, but men's scores had greater variability, which led to large asymmetries at the highest and lowest tails of the distribution. As one of Hedges and Nowell's more dramatic findings, despite only small differences at the midpoint of the distribution, men outnumbered women in the top 1 percent of mathematics and spatial reasoning by a ratio of seven to one.

These findings were consistent with those of many other studies. For example, Benbow and Stanley had reported men–women ratios among the top 0.1 percent of adolescents (i.e., one in a thousand) on the SAT–Mathematics of approximately 10-to-1 and in Stanley's seminal work with 12- to 14-years-olds who were recommended for a gifted program at Johns Hopkins University (the Study of Mathematically Precocious Youth, or SMPY), the highest-scoring girl's score was surpassed by 43 boys.

Biological Explanations

There are some grounds for positing a biologically based account for this apparent sex difference in mathematical giftedness, whether caused by innate differences in ability or other factors such as interests.

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