In mechanical reasoning, electronics information, and auto and shop information, boys also performed much better than girls, the study found. In areas such as mechanical comprehension and other vocational talents, 8 to 10 times as many boys as girls scored in the top 10 percent, according to the report.

On the other hand, boys were much more likely than girls to score near the bottom of the scale on tests of reading comprehension, memory and perceptual speed.

Hedges said the differences in scores between boys and girls showed remarkably little change between 1960, when the first survey was conducted, and 1992, the year of the most recent survey.

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That was disappointing, he said. Some people might use that as an argument that these differences are really biological. I think it’s equally plausible that the efforts to change things have been too little.

People who have careers in science and engineering are overwhelmingly more likely to have scored in the 90th percentile or higher on mathematics tests in high school, the study found.

Hedges suggested that if American society wants to achieve equal numbers of men and women in scientific and technical fields, we have to do seven times as good a job in recruiting women.

The study suggests boys are at an alarming disadvantage in their performance on writing tests, a finding with important implications for educational policy.

The generally larger numbers of males who perform near the bottom of the distribution in reading comprehension and writing will have difficulty finding employment in an increasingly information-driven economy, the report said.

Thus, some intervention may be required to enable them to participate constructively in the work force, it suggested.

Differences in the abilities of the sexs are likely to figure increasingly in policy discussions about salary fairness, the report noted. Economists have recently begun to use individual differences in test scores to explain sex differences in wages and occupational advancement.

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But the study sheds little light on the origin of sex difference in aptitude.

I believe the sex differences in abilities are caused by social constraints rather than biology, Hedges said.

Traditionally, there is more encouragement for men to learn math and science while women are encouraged to learn literature, he said. In the long run, we should change the opportunity structure in order to recruit more women to science.