If you want to call her Slugger, start throwing those fast balls early.

Researchers at the University of Michigan have found that stereotypes based on athletic prowess are firmly established by age 6 -- even though tests show that the skills of boys and girls that age are nearly equal.

The study involved tests of more than 4,000 elementary school students, combined with assessments of their athletic abilities by physical education teachers. These were then compared with children's ratings of their performance.

The boys consistently rated themselves as more skilled, particularly in throwing and catching, and termed sports more important and more enjoyable than girls did. Yet when researchers totaled the scores, boys performed only 2 percent better than did girls.

Self-assessment scores, however, indicated a substantial discrepancy between reality and perception: Six-year-old boys flexed their egos more than their muscles and rated themselves as being far more proficient than their scores indicated.

The gender disparities resembled those seen in children studying math and science, which increase with age.

"Throwing and catching a ball seems to be a fundamental part of how boys perceived themselves in sports," said Rena Harold, a specialist in achievement research at Michigan's Institute for Social Research. "If they can do that well, then they believe they are 'good at sports.' "

Girls indicated that they felt significantly less proficient in sports and rated themselves least confident about throwing and catching.

Parental attitudes strongly influenced how the youngsters rated their skills and how they felt about sports, the researchers found. Children of parents who expected more were likely to be self-confident and to perform better.

"It's not so much that the parents were saying, 'Gee, these girls don't have any talent,' " Harold said. "Instead, they were saying, 'These boys really have talent' . . . Because parents encouraged their boys more, they were providing more opportunities for these children to do better."