The more science reveals about the difference between the male and female brain, one simple fact emerges: We don’t know much. This is especially true when it comes to determining what sexually arouses men and women. While answers to this question have long been divided along gender lines, new research published Monday in Proceedings of the National Academy of Sciences suggests those divisions are not as firmly drawn as scientists thought. In fact, they may not exist at all.
Popular psychology posits that men are more visually oriented, responding to sexually arousing images or to the body of the person in front of them. Women, meanwhile, are thought to be more emotionally driven, experiencing sexual arousal as it relates to an intimate relationship. This thinking would suggest that men and women’s brains actually processed arousal differently. That is, something different was happening in their brains — perhaps even in different areas of their brains — in the time between seeing something sexual and responding with sexual arousal.
But in the new paper, published on Monday, a team from the Max Planck Institute for Biological Cybernetics investigated whether male brains and female brains responded differently to sexually arousing images and videos. In the end, they found no relationship between a person’s sex and how sexual arousal looks in their brain, despite previous research suggesting otherwise.
As the team writes, they “offer strong quantitative evidence that the neuronal response to visual sexual stimuli, contrary to the widely accepted view, is independent of biological sex.”
How Sexual Arousal Looks in the Male and Female Brain
Previous studies used fMRI (functional magnetic resonance imaging) to visualize the parts of the brain that become active when a person is aroused using sexually themed photos or videos. Many of those studies suggested that there are sex-based differences in the way the male and female brains look when they’re turned on, but the team’s new analysis shows that that’s not the case.
In a meta-analysis of 61 of these brain-imaging studies, which spanned 1,850 men and women of different sexual orientations, the team found no evidence that the differences in brain activation when people viewed sexual content were due to their sex.
“Visual sexual stimuli induce activation in the same cortical and subcortical regions in both men and women, while the limited sex differences that have been found and reported previously refer to subjective rating of the content,” they write.
In other words, most differences in brain activation had less to do with the viewer’s sex and more to do with whether they liked what they were seeing or not. Other differences, the team points out, were driven by whether the person was viewing videos or photos, but even these were not biased according to sex.
Accounting for Different Sexual Responses
The findings of the current study stand in opposition to past research showing sex differences in the way male and female brains become activated when they’re sexually aroused. Previous researchers who came to that conclusion suggested that those sex differences are rooted in differences in the gray matter volume between males and females.
Investigating this claim through a systematic review of research on this topic, which spanned 3,723 adults, the authors of the new study could not find any connection between gray matter differences and brain responses to sexual arousal. This area of study has a lot of uncertainty built into it as is, since the research on sex differences in brain mass is also inconclusive.
The findings of the new study are particularly convincing because the meta-analysis captures not only results from a large number of people but also people with diverse sexual orientations and identities, including men and women who are gay, straight, bisexual, and transsexual. Past studies often used too few people to draw meaningful conclusions or relied too heavily on data from heterosexual men, which the authors say may have skewed the results.
Another factor that may have previous biased results are attitudes toward sexual material, the team points out. However, they recognize the research showing that men and women evaluate sexual stimuli differently, which suggests that even if male and female brains respond to sexual content in the same way, sex-linked preferences could still exist.
This latest study just shows that these differences don’t look the way we thought they did.
Abstract: Sexual arousal is a dynamical, highly coordinated neurophysiological process that is often induced by visual stimuli. Numerous studies have proposed that the cognitive processing stage of responding to sexual stimuli is the first stage, in which sex differences occur, and the divergence between men and women has been attributed to differences in the concerted activity of neural networks. The present comprehensive metaanalysis challenges this hypothesis and provides robust quantitative evidence that the neuronal circuitries activated by visual sexual stimuli are independent of biological sex. Sixty-one functional magnetic resonance imaging studies (1,850 individuals) that presented erotic visual stimuli to men and women of different sexual orientation were identified. Coordinate-based activation likelihood estimation was used to conduct metaanalyses. Sensitivity and clustering analyses of averaged neuronal response patterns were performed to investigate robustness of the findings. In contrast to neutral stimuli, sexual pictures and videos induce significant activations in brain regions, including insula, middle occipital, anterior cingulate and fusiform gyrus, amygdala, striatum, pulvinar, and substantia nigra. Cluster analysis suggests stimulus type as the most, and biological sex as the least, predictor for classification. Contrast analysis further shows no significant sex-specific differences within groups. Systematic review of sex differences in gray matter volume of brain regions associated with sexual arousal (3,723 adults) did not show any causal relationship between structural features and functional response to visual sexual stimuli. The neural basis of sexual arousal in humans is associated with sexual orientation yet, contrary to the widely accepted view, is not different between women and men.