Sex and Gender Differences

Studying Gender Differences

The magnitude of gender differences is typically assessed with a measure called an effect size. The effect size is a standardized measure that denotes how big the difference between the average man and the average woman is, relative to the typical amount of difference seen between different men or different women. If the difference between the average man and average woman is no bigger than what is seen between individuals of the same gender, then the effect size is zero. On the other hand, a “large” effect size would mean that the average man (with 50% of men scoring above him and 50% below him) had a score above or below at least 75% of women. Thus, large effect sizes still have a fair amount of overlap between the genders, but the differences should be noticeable for the population overall.

The most convincing evidence on psychological gender differences is provided by a type of study called meta-analysis. Meta-analysis is a statistical technique that synthesizes the results of dozens (sometimes hundreds) of small studies to give an overall summary of all the research that has been done on a particular topic. A meta-analysis, then, is stronger than any one particular study, because it allows the researchers to discern whether their results are consistent across studies, how big the effect size typically is, and whether gender effects are consistent across different groups and contexts.

Current Evidence about Gender Differences and Similarities

Evidence from the most intensely studied areas of psychological research shows that the differences between men and women are small or nonexistent for most aspects of cognitive function, communication, social behavior and personality, and psychological well-being. However, there are a few exceptions. Most notably, there are moderate to large gender differences in aggression, attitudes about sexuality, and motor behaviors.

Regarding cognitive functioning, men and women are about equal in mathematics performance and most components of verbal ability, such as vocabulary and reading comprehension. However, most research does show a gender difference in spatial abilities, with boys showing moderately better spatial perception and mental rotation than girls show.

Gender differences in communication are minimal. Men and women are about equally talkative and show only slight differences in the propensity to self-disclose or to interrupt another when engaged in conversation. Women are somewhat more likely to smile than men during typical conversations, but the gender difference in smiling is smaller when men and women believe no one is watching.

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