Sex Differences in Personality are Large and Important

By Alex Tabarrok

Men and women are different. A seemingly obvious fact to most of humanity but a long-time subject of controversy within psychology. New large-scale results using better empirical methods are resolving the debate, however, in favor of the person in the street. The basic story is that at the broadest level (OCEAN) differences are relatively small but that is because there are large offsetting differences between men and women at lower levels of aggregation. Scott Barry Kaufman, writing at Scientific American, has a very good review of the evidence:

At the broad level, we have traits such as extraversion, neuroticism, and agreeableness. But when you look at the specific facets of each of these broad factors, you realize that there are some traits that males score higher on (on average), and some traits that females score higher on (on average), so the differences cancel each other out. This canceling out gives the appearance that sex differences in personality don’t exist when in reality they very much do exist.

For instance, males and females on average don’t differ much on extraversion. However, at the narrow level, you can see that males on average are more assertive (an aspect of extraversion) whereas females on average are more sociable and friendly (another aspect of extraversion). So what does the overall picture look like for males and females on average when going deeper than the broad level of personality?

On average, males tend to be more dominant, assertive, risk-prone, thrill-seeking, tough-minded, emotionally stable, utilitarian, and open to abstract ideas. Males also tend to score higher on self-estimates of intelligence, even though sex differences in general intelligence measured as an ability are negligible [2]. Men also tend to form larger, competitive groups in which hierarchies tend to be stable and in which individual relationships tend to require little emotional investment. In terms of communication style, males tend to use more assertive speech and are more likely to interrupt people (both men and women) more often– especially intrusive interruptions– which can be interpreted as a form of dominant behavior.

…In contrast, females, on average, tend to be more sociable, sensitive, warm, compassionate, polite, anxious, self-doubting, and more open to aesthetics. On average, women are more interested in intimate, cooperative dyadic relationships that are more emotion-focused and characterized by unstable hierarchies and strong egalitarian norms. Where aggression does arise, it tends to be more indirect and less openly confrontational. Females also tend to display better communication skills, displaying higher verbal ability and the ability to decode other people’s nonverbal behavior. Women also tend to use more affiliative and tentative speech in their language, and tend to be more expressive in both their facial expressions and bodily language (although men tend to adopt a more expansive, open posture). On average, women also tend to smile and cry more frequently than men, although these effects are very contextual and the differences are substantially larger when males and females believe they are being observed than when they believe they are alone.

Moreover, the differences in the subcategories are all correlated so while one might argue that even among the subcategories the differences are small on any single category when you put them all together the differences in male and female personalities are large and systematic.

Relatively small differences across multiple traits can add up to substantial differences when considered as a whole profile of traits. Take the human face, for example. If you were to just take a particular feature of the face– such as mouth width, forehead height, or eye size– you would have difficult differentiating between a male face and a female face. You simply can’t tell a male eyeball from a female eyeball, for instance. However, a look at the combination of facial features produces two very distinct clusters of male vs. female faces. In fact, observers can correctly determine sex from pictures with greater than 95% accuracy [4]. Here’s an interesting question: does the same apply to the domain of personality?

…There now exists four large-scale studies that use this multivariate methodology (see here, here, here, and here). All four studies are conducted cross-culturally and report on an analysis of narrow personality traits (which, as you may recall, is where most of the action is when it comes to sex differences). Critically, all four studies converge on the same basic finding: when looking at the overall gestalt of human personality, there is a truly striking difference between the typical male and female personality profiles.

Just how striking? Well, actually, really striking. In one recent study, Tim Kaiser, Marco Del Giudice, and Tom Booth analyzed personality data from 31,637 people across a number of English-speaking countries. The size of global sex differences was D = 2.10 (it was D = 2.06 for just the United States). To put this number in context, a D= 2.10 means a classification accuracy of 85%. In other words, their data suggests that the probability that a randomly picked individual will be correctly classified as male or female based on knowledge of their global personality profile is 85% (after correcting for the unreliability of the personality tests).

In other words, you can predict whether a person is male of female from their personality traits almost as well as by looking at their face. Overall, the big differences are as follows:

Consistent with prior research, the researchers found that the following traits are most exaggerated among females when considered separately from the rest of the gestalt: sensitivity, tender-mindedness, warmth, anxiety, appreciation of beauty, and openness to change. For males, the most exaggerated traits were emotional stability, assertiveness/dominance, dutifulness, conservatism, and conformity to social hierarchy and traditional structure.

I have also pointed out that gender equality magnifies differences in gender choices and behavior which is probably one reason why fewer women enter STEM fields in societies with greater equality. Consistent with this, personality differences between the sexes are large in all cultures but “for all of these personality effects the sex differences tend to be larger– not smaller– in more individualistic, gender-egalitarian countries.”