CHICAGO, March 28 (Xinhua) -- Gender differences in vocational interests increase drastically during puberty but tend to decrease across the lifespan, a study posted Tuesday on the website of the University of Illinois (UI) shows.

Involving more than 20,000 people ranging in age from 11 to 42, UI researchers conducted a meta-analysis of 49 longitudinal studies on vocational interests to explore when gender disparities emerge and how they change across different developmental periods from early adolescence to middle adulthood.

The researchers found that gender differences in these vocational interests widened significantly during early adolescence.

During middle school, both boys' and girls' interest in realistic vocations declined, but girls' interest declined much more steeply than boys' during that time.

Conversely, girls' interest in social-oriented vocations increased slightly during middle school while boys' interest dropped off sharply.

Then, the researchers found that these patterns began to reverse as youths entered late adolescence. Girls' interest in such realistic vocational activities as those that involved using tools or manipulating objects began to increase around age 14 and continued to rise throughout their young and middle adult years.

By contrast, men's interest in realistic work activities remained constant from late adolescence through their early 40s.

Similar trends were found with social interests. Women's interest in people-oriented occupations remained relatively constant from early adolescence onward, while males' interest in working with people increased significantly.

"Vocational interests associated with the opposite gender increased during young adulthood, while interests stereotypically associated with their same gender remained constant," said Kevin A. Hoff, a doctoral student in industrial-organizational psychology at UI.

"Men's interest in people-oriented activities may be influenced by the roles they take on during adulthood, as marital partners, parents and professionals," said co-author James Rounds, a professor of psychology and of educational psychology at UI.

Schools often begin assessing children's interests and aptitudes during middle school. But the study found that might not be the optimal time.

"Children's interests in basically everything plummets during early adolescence," Hoff said. "If we want to spark kids' interest in careers, it may be best to wait until late adolescence when they're in high school, and their interest levels increase again."

The same might be true for gender-diversity programs seeking to attract females to male-dominated fields, Hoff said. These programs might have greater success if their outreach and recruitment efforts targeted females in late adolescence, when girls' interest in realistic activities begins to rise.

The study has been published in the American Psychological Association's journal Psychological Bulletin.