Men and Women: No Big Difference

Studies show that one's sex has little or no bearing on personality, cognition and leadership.

The Truth about Gender "Differences"

Mars-Venus sex differences appear to be as mythical as the Man in the Moon. A 2005 analysis of 46 meta-analyses that were conducted during the last two decades of the 20th century underscores that men and women are basically alike in terms of personality, cognitive ability and leadership. Psychologist Janet Shibley Hyde, PhD, of the University of Wisconsin in Madison, discovered that males and females from childhood to adulthood are more alike than different on most psychological variables, resulting in what she calls a gender similarities hypothesis. Using meta-analytical techniques that revolutionized the study of gender differences starting in the 1980s, she analyzed how prior research assessed the impact of gender on many psychological traits and abilities, including cognitive abilities, verbal and nonverbal communication, aggression, leadership, self-esteem, moral reasoning and motor behaviors.

Hyde observed that across the dozens of studies, consistent with the gender similarities hypothesis, gender differences had either no or a very small effect on most of the psychological variables examined. Only a few main differences appeared: Compared with women, men could throw farther, were more physically aggressive, masturbated more, and held more positive attitudes about sex in uncommitted relationships.

Furthermore, Hyde found that gender differences seem to depend on the context in which they were measured. In studies designed to eliminate gender norms, researchers demonstrated that gender roles and social context strongly determined a person's actions. For example, after participants in one experiment were told that they would not be identified as male or female, nor did they wear any identification, none conformed to stereotypes about their sex when given the chance to be aggressive. In fact, they did the opposite of what would be expected - women were more aggressive and men were more passive.

Finally, Hyde's 2005 report looked into the developmental course of possible gender differences - how any apparent gap may open or close over time. The analysis presented evidence that gender differences fluctuate with age, growing smaller or larger at different times in the life span. This fluctuation indicates again that any differences are not stable.

Learning Gender-Difference Myths

Media depictions of men and women as fundamentally "different" appear to perpetuate misconceptions - despite the lack of evidence. The resulting "urban legends" of gender difference can affect men and women at work and at home, as parents and as partners. As an example, workplace studies show that women who go against the caring, nurturing feminine stereotype may pay dearly for it when being hired or evaluated. And when it comes to personal relationships, best-selling books and popular magazines often claim that women and men don't get along because they communicate too differently. Hyde suggests instead that men and women stop talking prematurely because they have been led to believe that they can't change supposedly "innate" sex-based traits.

Hyde has observed that children also suffer the consequences of exaggerated claims of gender difference -- for example, the widespread belief that boys are better than girls in math. However, according to her meta-analysis, boys and girls perform equally well in math until high school, at which point boys do gain a small advantage. That may not reflect biology as much as social expectations, many psychologists believe. For example, the original Teen Talk Barbie ™, before she was pulled from the market after consumer protest, said, "Math class is tough."

As a result of stereotyped thinking, mathematically talented elementary-school girls may be overlooked by parents who have lower expectations for a daughter's success in math. Hyde cites prior research showing that parents' expectations of their children's success in math relate strongly to the children's self-confidence and performance.

Moving Past Myth

Hyde and her colleagues hope that people use the consistent evidence that males and females are basically alike to alleviate misunderstanding and correct unequal treatment. Hyde is far from alone in her observation that the clear misrepresentation of sex differences, given the lack of evidence, harms men and women of all ages. In a September 2005 press release on her research issued by the American Psychological Association (APA), she said, "The claims [of gender difference] can hurt women's opportunities in the workplace, dissuade couples from trying to resolve conflict and communication problems and cause unnecessary obstacles that hurt children and adolescents' self-esteem."

Psychologist Diane Halpern, PhD, a professor at Claremont College and past-president (2005) of the American Psychological Association, points out that even where there are patterns of cognitive differences between males and females, "differences are not deficiencies." She continues, "Even when differences are found, we cannot conclude that they are immutable because the continuous interplay of biological and environmental influences can change the size and direction of the effects some time in the future."

The differences that are supported by the evidence cause concern, she believes, because they are sometimes used to support prejudicial beliefs and discriminatory actions against girls and women. She suggests that anyone reading about gender differences consider whether the size of the differences are large enough to be meaningful, recognize that biological and environmental variables interact and influence one other, and remember that the conclusions that we accept today could change in the future.

Cited Research

Archer, J. (2004). Sex differences in aggression in real-world settings: A meta-analytic review. Review of General Psychology, 8, 291-322.

Barnett, R. & Rivers, C. (2004). Same difference: How gender myths are hurting our relationships, our children, and our jobs. New York: Basic Books.

Eaton, W. O., & Enns, L. R. (1986). Sex differences in human motor activity level. Psychological Bulletin, 100, 19-28.

Feingold, A. (1994). Gender differences in personality: A meta-analysis. Psychological Bulletin, 116, 429-456.

Halpern, D. F. (2000). Sex Differences in Cognitive Abilities (3rd Edition). Mahwah, NJ: Lawrence Erlbaum, Associates, Inc. Publishers.

Halpern, D. F. (2004). A cognitive-process taxonomy for sex differences in cognitive abilities. Current Directions in Psychological Science, 13 (4), 135-139.

Hyde, J. S., Fennema, E., & Lamon, S. (1990). Gender differences in mathematics performance: A meta-analysis. Psychological Bulletin, 107, 139-155.

Hyde, J. S. (2005). The Gender Similarities Hypothesis. American Psychologist, Vol. 60, No. 6.

Leaper, C. & Smith, T. E. (2004). A meta-analytic review of gender variations in children's language use: Talkativeness, affiliative speech, and assertive speech. Developmental Psychology, 40, 993-1027.

Oliver, M. B. & Hyde, J. S. (1993). Gender differences in sexuality: A meta-analysis. Psychological Bulletin, 114, 29-51.

Spencer, S. J., Steele, C. M. & Quinn, D. M. (1999). Stereotype threat and women's math performance. Journal of Experimental Social Psychology, 35, 4-28.

Voyer, D., Voyer, S., & Bryden, M. P., (1995). Magnitude of sex differences in spatial abilities: A meta-analysis and consideration of critical variables. Psychological Bulletin, 117, 250-270.


American Psychological Association, October 20, 2005