Photo: AMC

Neuroscientists, for obvious reasons, are really interested in finding out what’s different about the brains of people with unpleasant personalities, such as narcissists, or unsavory habits, like porn addiction. Their hope is that by studying these people’s brains we might learn more about the causes of bad character, and ways to helpfully intervene. Now to the list of character flaws that’ve received the brain-scanner treatment we can apparently add sexism — a new Japanese study published in Scientific Reports claims to have found its neurological imprint.

The researchers wanted to know whether there is something different about certain individuals’ brains that potentially predisposes them to sexist beliefs and attitudes (of course, as with so much neuroscience research like this, it’s very hard to disentangle whether any observed brain differences are the cause or consequence of the trait or behavior that’s being studied, a point I’ll come back to). More specifically, they were looking to see if people who publicly endorse gender inequality have brains that are anatomically different from people who believe in gender equality.

In short, it seems the answer is yes. Neuroscientist Hikaru Takeuchi at Tohoku University and his colleagues have identified two brain areas where people who hold sexist attitudes have different levels of gray-matter density (basically, a measure of how many brain cells are packed into a given area), as compared with people who profess a belief in gender equality (their study doesn’t speak to any subconsciously held sexist beliefs). What’s more, these neural differences were correlated with psychological characteristics that could help explain some people’s sexist beliefs.

The researchers scanned the brains of 681 students — the average age was 21, and 306 of the participants were women — and also asked them to complete a measure of their belief in “Sex Role Egalitarianism” (SRE). The scale is basically a series of statements that participants rate their agreement with — two examples are “Domestic chores should be shared between husband and wife” (agreement would be a sign of high SRE) and “Bringing up children is the most important job for a woman” (agreeing with this would suggest low SRE). People who score highly on this trait believe that “the sex of an individual should not influence the perception of his or her rights, abilities, obligations, and opportunities,” as the authors of the new study put it. The participants also completed a host of other psych measures, including IQ and personality tests and a questionnaire about aggressive tendencies.

Takeuchi’s team found that lower scores on the SRE scale (that is, holding more sexist or gender-discriminating beliefs) tended to correlate, in men and women, with having more dense gray matter in the posterior cingulate cortex, an area in the brain associated with processing things like anger, fear, and pain; and with reduced gray-matter density in the right amygdala, another brain area that’s very important to emotions, especially fear. In terms of their broader psychological profile, people who espoused sexist beliefs tended to score higher in their anger, depression-proneness, and competitiveness, which fits previously published research into the personality correlates of sexism.

These new brain-scan results suggest there’s something different about the brain structure of people with sexist beliefs, but what to make of these differences? It’s very difficult to interpret simple anatomical differences because less volume in certain brain areas can sometimes be a good thing — for example, as a mark of chess expertise — while other times it can be suggestive of lost function, such as when the brain shrinks in Alzheimer’s disease.

In the current context, we can at least look for clues in the other psychological scores the researchers collected. For example, they found that having more gray matter in the posterior cingulate didn’t just correlate with sexist beliefs but also (albeit weakly) with being more prone to anger and hostility, and with being competitive. Meanwhile, having less gray matter in the right amygdala correlated weakly with higher scores on neuroticism (among women) and being more depressive. There’s also some relevant prior research that’s shown that reduced amygdala volume is associated with stress, anxiety, and depression (though note that other research has linked an enlarged amygdala with emotional problems — unfortunately, neuroscience is rarely straightforward!).

The new findings paint a picture of people (men and women) who hold sexist beliefs as psychologically vulnerable folk who are fearful and competitive. We need to be aware that this study hasn’t proved that having a certain brain anatomy causes people to be sexist (it’s just as plausible that holding sexist beliefs changes the brain, or that other factors, such as one’s upbringing or social circumstances, shape one’s beliefs and brain structure). But it’s probably fair to speculate that some people may have a brain anatomy that predisposes them to be afraid of competition and cultural changes that could imperil their own interests, thus laying the foundation for their endorsement of gender inequality.

However, the researchers don’t stop there. They go so far as to suggest their findings could hint at ways of intervening to combat sexist attitudes. For example, they say there’s evidence that when people successfully reduce their negative emotions, this results in increases to the gray matter in the right amygdala. “Therefore,” the researchers write, “improving negative mood may prevent stereotype on sex role [i.e. reduce gender discrimination] and may mitigate a wide range of problems associated with lower Sex Role Egalitarianism.”

Their message seems to be this: If you want to do your little bit to help achieve gender equality, try hugging a sexist. Or at least listen to their problems. You’ll cheer them up, calm them down, their amygdala might grow a bit, and — who knows? — maybe women might start to get equal pay with men a little bit sooner. Just one problem: I checked out that study they cited for showing that the amgydala grows as people manage to reduce their stress levels, and actually it found the very opposite, that “the more participants’ stress levels decreased, the greater the decrease of gray matter density in the right amygdala [emphasis added].” So maybe hold off on hugging your favorite sexist for now.

Dr. Christian Jarrett (@Psych_Writer), a Science of Us contributing writer, is editor of the British Psychological Society’s Research Digest blog. His latest book is Great Myths of the Brain.