There’s no such thing as the “male” and “female” brain, according to psychologist Gina Rippon. They are one and the same, she argues in her new book, “Gender and Our Brains: How New Neuroscience Explodes the Myths of the Male and Female Minds.”

In her new book “Gender and Our Brains,” cognitive neuroimaging professor Gina Rippon explains that brains aren’t gendered, but research can be.

Rippon sifts through centuries of research into supposed differences in areas such as behavior, skills, and personality, and shows that external factors like gender stereotypes and real-world experiences are the likely cause of any detectable differences in mental processing. And she demonstrates that the differences among women as a group, or among men as a group, are much greater than the differences between men and women.

She cites a 2015 study looking at 1,400 brain scans as an example. Comparing 160 brain structures in the scans — identifying areas that were, on average, larger in men or in women — researchers could not find any scans that had all “male” traits, or all “female” traits — physical attributes such as weight or tissue thickness. “The images were, literally, of a mosaic,” she says. “We’re trying to force a difference into data that doesn’t exist.”

Rippon teaches cognitive neuroimaging — the study of behavior through brain images — at Aston University in England. For this installment of the Undark Five, I spoke with her about how neuroimages are misinterpreted and whether PMS is real, among other topics. Here is our conversation, edited for length and clarity.

Undark: Scientists have been trying to find differences in the brains of men and women for years. What are some examples of how the cherry-picking approach is problematic?

Gina Rippon: It’s what I call the “hunt the differences” agenda, which started about 200 years ago when scientists were starting to understand the importance of the brain in explaining human behavior and human ability.

And they looked at society and they saw that women were … inferior to men in their place in society, access to education achievements. And they took that status quo and then said, “Well, we’re researchers entering an amazing new world of understanding the brain, so we’ll show that these differences between men and women come from differences in their brains.”

And that’s really very overtly informed their research agenda from the beginning — they were trying to explain the status quo and not just trying to see what brains were like.

That continues to this day, in that the very name of their research is about sex differences. And so, psychologists are saying, “Men and women are different, so let’s have a look at the brain, see if we can find where in the brain these differences come from.”

One of the very first studies was a language study, by a researcher called Shaywitz, who was trying to demonstrate that men and women processed language differently. They used four different tasks, and one of the tasks showed glimmerings of a sex difference — [in a] very small group of participants in this case — and women processed language using both sides of their brain, and men processed language using one side of their brain. And that fitted in neatly with existing preconceptions about differences in language abilities and language use. That particular finding has proved to have remarkable stickability: People still think that there is this sort of very profound sex difference in how men and women process language.

UD: You teach cognitive neuroimaging, yet you write about the problems in the early days of neuroimaging with how the pictures were interpreted. When certain areas of the brain that are activated are color-coded, for instance, we often perceive a greater change than really exists. How does this happen?

GR: We’ve got this really complex data — hundreds of channels of brain-imaging data collected over an hour, say — and there was a need to explain what this was showing. The color-coding was really a way of highlighting the differences that people found — they weren’t a representation of what was actually going on in the brain.

So if you were carrying out, for example a brain-imaging study, and you’re interested in memory, you would put your female or male participants in your scanner and give them a task such as just reading different words. Once you’d tidied up your data, you’d try and find some kind of difference in brain activity associated with your task. But the differences you find are very tiny and buried in all the other “brain chatter” which is pretty much continuous.

So you set a particular threshold saying “I’m only interested in differences, which are bigger than this amount. And gradually, you focus in on those differences”. And then you allocate them, you select an agreed upon standard of differences, “I’m going to call it red. It’s an increase. And I’m going to call it blue, if it’s a decrease.” You’ve got very compelling images, which show a distribution of a different color.

But what you’re really looking at is the end product of a very complicated series of image manipulation and statistical analysis, which isn’t fraudulent, but it’s just saying, “We found a way of showing you the differences that we’re interested in.” But people will say, “This part of the brain lights up when somebody’s memorizing words” — which isn’t really what happens.

UD: There are certain mental tasks in information processing, such as spatial skills, map reading, or constructing and manipulating three-dimensional objects, in which men, on average, outperform women. How have these differences emerged?

GR: Spatial skills supposedly [show] a robust sex difference — that men on average perform better on tasks involving spatial thinking than women. Because this is such an apparently reliable finding, it is claimed that it is evidence of an innate, biologically-based aptitude.

But if you take into account spatial experience — people who’ve played with construction toys or play high-action videogames or have hobbies which involve some kind of spatial processing such as building cars or playing darts — that’s a much better predictor of who’s going to be a better spatial thinker.

If you match women with high levels of visuospatial experience with men with the same level, the differences between men and women disappear. What looks like a sex difference has actually arisen from something different — that difference is the gendered opportunities that society may offer to individuals.

UD: You write that sex differences in the brain, or behavior, are often attributed to hormones. For instance, PMS is often associated with “dramatic outbursts of negative mood, poor performance in school or at work, overall decline in cognitive competence.” How do hormones relate to the brain?

GR: With the PMS example, I was tapping into the old idea that women are inferior because of their “biological vulnerability,” because of the physical differences associated with their role in the reproductive cycle. In the 19th century, the suggestion was that they shouldn’t be exposed to education because it could affect their reproductive system.

In talking about the way that beliefs in biological vulnerability might be challenged, I joked about the only questionnaire associated with menstruation: the “menstrual distress questionnaire.” I said there should be an “ovulation euphoria questionnaire” as well. [I found] research which demonstrated that at the point of ovulation, there are some very positive effects on women’s perceptual skills and behaviors — but we don’t tend to hear so much about those. That’s an imbalance in how these findings are reported.

If you believe a particular syndrome exists, you will attribute differences you’re experiencing to that syndrome.

Of course, hormones do affect our behavior. The brain is very flexible throughout our lives, and the human brain is more affected by external demands, including social attitudes and expectations, than any other species. It’s good for us to be social beings, but it’s bad for us if the expectations and attitudes are negative.

We now know that hormones are as flexible and responsive to social situations as the brain. We know that testosterone levels reflect the kind of social situation a man finds himself in. So testosterone levels of new fathers are much lower than testosterone levels of fathers who are not primary carers of new children.

UD: Can we learn anything from looking at the brains of people who are non-gender-identifying? Or trans?

GR: I’m trying to break the idea that there’s an inevitable link between being male [or female], having XX or XY chromosomes and the particular kind of brain you have. But it’s a well-entrenched belief, and informs a lot of expectations we have.

With transgender individuals, or individuals who don’t adhere to the standard binary of male/female, it’s quite clear that the link is not inevitable. [Many] claim, “I was born with a female brain in a male body.” It’s quite challenging if someone like me comes along and says, “There’s no such thing as a female brain.”

But every brain is different from every other brain, and our brains are mosaics of all sorts of different characteristics. No brain is wholly “male” or wholly “female.” We’re starting to unpack that equation.

Hope Reese is a writer and editor in Louisville, Kentucky. Her writing has appeared in Undark, The Atlantic, The Boston Globe, The Chicago Tribune, Playboy, Vox, and other publications.