Gender Similarities Hypothesis

The Hypothesis

The gender similarities hypothesis was most recently articulated by psychologist Janet Shibley Hyde following decades of research on psychological gender differences and similarities. Hyde echoed the observations of early-20th-century scholars Edward Lee Thorndike, Leta Stetter Hollingworth, and Helen Thompson Woolley—all of whom had previously studied gender differences and concluded that there were minimal differences between the sexes in mental capacities and psychological traits. Similarly, Hyde observed that contemporary popular media tends to focus on and exaggerate gender differences between men and women, despite research evidence that gender differences on most psychological attributes are small or negligible. Hyde argued that overemphasizing gender differences has the potential to harm both men and women. Instead, she argued, researchers and popular media should acknowledge the few key areas in which men and women differ, but on the whole emphasize the evidence that men and women are more alike than they are different.

The Evidence

In support of the gender similarities hypothesis, Hyde reviewed 46 meta-analyses, covering gender differences in six broad areas: cognitive abilities, communication, personality and social behavior, psychological well-being, motor behavior, and miscellaneous. Meta-analysis aggregates all of the research that has been done on a particular question by statistically combining dozens—sometimes hundreds of studies on the topic. Meta-analysis is therefore more reliable than any single study, and it can produce a clear picture of whether a gender difference really exists, how big that difference is, and whether the gender difference appears consistently across all studies or varies depending on context. In addition to the meta-analyses, data from large national probability samples were also reviewed when available because their size and comprehensive sampling strategies also equip them to provide strong evidence about the existence and magnitude of gender differences.

The sources that Hyde reviewed provided 128 estimates of gender differences across a wide variety of attributes. A majority of those estimates (78%) showed small or negligible gender differences. Thus, most psychological variables that have been intensely studied show very small or nonexistent gender differences.

Furthermore, the topics covered by the meta-analyses were often studied precisely because they were widely believed to be areas of gender difference, perhaps making the pattern of gender similarities all the more striking. Among the gender-stereotyped domains where research actually shows gender similarity are mathematics performance, vocabulary, reading comprehension, talkativeness, self-disclosure, helping behavior, self-esteem, and leadership effectiveness.

The Exceptions

Despite the overwhelming evidence of gender similarities, a few areas emerged where gender differences were consistent and substantial. First, the sexes show large differences in motor performance, with men having greater grip strength, throwing velocity, throwing distance, and sprinting speed than women. Second, there are large gender differences in some aspects of sexuality. In particular, men tend to have more permissive attitudes toward casual sex than women do. Third, there are gender differences in patterns of aggression. Men tend to be more physically aggressive than women, and to a lesser extent, men are also more verbally aggressive than women. However, some evidence indicates that women may be more prone to relational aggression than men are.

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