Male-to-female transsexuals have "male" brains

People with "gender dysphoria" feel as though their sexual identity doesn't match their biological sex. A popular theory is that such people have a brain with physical characteristics that match the sex they identify with. So, for a man who feels like he is a woman - a male-to-female transsexual - the proposal is that he has a female brain "trapped" in a male body. Now in one of the first studies of its kind, Ivanak Savic and Stefan Arver have scanned the brains of 24 heterosexual, pre-operative male-to-female transsexuals and compared their structure to the brains of 24 heterosexual male and 24 heterosexual female controls. Homosexual transsexuals were omitted to help avoid the complicating influence of sexuality on the results. None of the transsexual participants had taken any hormone treatments, which is another factor that could have skewed the findings.

The scans threw up several of the structural brain differences associated with biological sex that have been reported before. For example, the men's brains had more grey matter in the cerebellum (involved in motor control) and lingual gyrus (involved in vision) and less gray matter and white matter in the precentral sulcus (part of the frontal lobe), compared with the women's brains. The men also had smaller hippocampi (involved in memory) than the women. In all these respects the brains of the male-to-female transexuals resembled the brains of the male control group. Likewise, the male-to-female transsexuals, like the male controls, had more asymmetric brains than the female controls. "The present study does not support the dogma that male-to-female transsexuals have atypical sex dimorphism in the brain but confirms the previously reported sex differences in structural volumes, gray, and white matter fractions," the researchers said. In other words, the male-to-female transsexuals may have felt like women, but their brains had structural characteristics typical of men.

But that's not to say that the male-to-female transsexual participants had brains that were unremarkable. Compared with the male and female controls, they had a smaller thalamus (the brain's relay centre) and putamen (an area involved in motor control) and increased gray matter in the right insula and inferior frontal cortex (regions involved in representing the body, among other functions). Savic and Arver advised treating these differences with caution. They've never been found before so need to be replicated with a larger sample. And even if confirmed, it's not clear what these differences mean, or whether they are a cause or consequence of gender dysphoria. "One highly speculative thought is that the enlargement of the ... insular and inferior frontal cortex ... could derive from a constant rumination about one's own body," the researchers said.

More research is needed, with larger samples and including studies of homosexual transsexuals and female-to-male transsexuals. "Any interpretation must, therefore, proceed cautiously and can at this point only be highly speculative," the researchers said.
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Savic, I., and Arver, S. (2011). Sex Dimorphism of the Brain in Male-to-Female Transsexuals. Cerebral Cortex, 21 (11), 2525-2533 DOI: 10.1093/cercor/bhr032

Post written by Christian Jarrett for the BPS Research Digest.

Hour-glass figure activates the neural reward centre of the male brain

There's little doubt that many conceptions of attractiveness are faddish - the size zero female model being an obvious example. However, other notions of beauty are more hard-wired, perhaps reflecting an evolutionary adaptation. These aspects of appearance have come to be associated with fertility, signifying 'reproductive fitness' to potential mates. Male facial symmetry is one example. Another is the hour-glass female form. Men in cultures across the world report a preference for women with a lower waist-to-hip ratio. And women with this body shape tend to be more fecund.

Now Steven Platek and Devendra Singh have provided brain imaging evidence to complete the picture. They've shown that the reward centres of men's brains fired up in response to the sight of naked women who'd chosen to have cosmetic surgery to accentuate the curviness of their figures. By contrast, changes to the women's body mass index - including increased slimness - had no such effect. Platek and Devendra said the finding could explain 'some men's proclivity to develop preoccupation with stimuli depicting optimally designed women' - i.e. porn. The weaker neural response to slimness, by contrast, suggests 'BMIs role in [attractiveness] evaluations is less the product of evolved psychological mechanisms and more the part of culturally driven, or societal based norms and perceptions.'

Platek and Singh made their observations after asking men to look at photographs of women taken before and after they'd undergone surgery in pursuit of an hour-glass figure. The post-op pictures triggered more brain activity in reward-evaluation areas such as the orbitofrontal cortex. The surgery had the effect of lowering the women's waist-to-hip ratio and there were also slight changes to their BMI scores. The former change was associated with more reward-related activity in the men's brains whereas changes to BMI was only associated with activity adjustments in lower-level visual brain areas. Finally, increases in the attractiveness ratings given by the men to the post-op pictures were associated with activation in neural reward areas, such as the nucleus accumbens, which are also involved in drug-based reward and craving.
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Platek, S., & Singh, D. (2010). Optimal Waist-to-Hip Ratios in Women Activate Neural Reward Centers in Men. PLoS ONE, 5 (2) DOI: 10.1371/journal.pone.0009042

Evidence-based tips for Valentine's

Need to woo a partner in time for Valentine's? Follow these simple, evidence-based instructions for boosting your irresistibility ...

When asking a lady for a dance or for her number, your chances will be improved by lightly touching her on the arm. Try not to do it in a creepy way.

Use mimicry, bodily and verbal. Use mimicry, bodily and verbal (see what I did there?)

If you're male, try to make yourself look taller and vice versa for women.

Hire a sports car, if you're a man, but don't bother if you're a woman. Both sexes should avoid Toyotas - that's a joke, please don't sue, they're lovely cars.

When flirting with a man, use direct, no-nonsense chat up lines rather than the subtle or witty approach. Men are very easily confused you know.

When wooing a woman, use chat-up lines that demonstrate your helpfulness, generosity, athleticism, ‘culture’ and wealth. Don't bother with jokes, empty compliments and sexual references. This ought to do it - 'Hey gorgeous, sorry I'm late: the opera over-ran, then I had to race to my neighbour's to help carry her piano upstairs - the one I bought her as a moving-in present'.

Try not to come across as too desperate. Don't, whatever you do, admit to reading this blog post.

If you're a really handsome man, don't show off your wealth too much - women might just conclude that you're likely to be unfaithful in the future. And anyway Mr Clooney, I'm sure you don't need these tips.

You hunky smile magnet! Here's a good one for heterosexual men: get friends of the opposite sex to smile at you. Women apparently find a man's face more attractive after it's been smiled at by a woman.

If you're a larger woman, keep your chosen man hungry and he's more likely to find you attractive.

Don't flirt and drive! Remember gentleman, interacting with a lady can impair your cognitive faculties.

Wear red. If nothing else, your little scarlet number will match your blushing cheeks as you smile with bashful pride at the compliment your date (hopefully) just paid you.

Desperate situations require desperate measures. If, despite all your romantic efforts, your date remains decidedly unfrisky, you could try reminding them of death. Warning: This could backfire.

Finally, here's a Time magazine article on flirting, just to get you in the mood.

Happy Valentine's day for Monday! (Apologies for male, heterosexual bias.)

Image credit: Clandestini

Shiny, swanky car boosts men's appeal to women, but not women's appeal to men

It's a widely held, if much derided, belief that ownership of a prestige sports car can increase a man's sex appeal to women. Indeed, there's a scene in the American sit-com Friends in which Joey dons a ridiculous Porsche-branded costume of peak cap, gloves, jacket and trousers, so determined is he to convince female passers-by that he owns a fast, shiny car. Now Michael Dunn and Robert Searle have tested the shiny car effect scientifically, looking at the influence of apparent car ownership on both male and female perceived attractiveness.

Hundreds of passers-by in Cardiff city centre were asked to rate the attractiveness of a young man or woman portrayed in a photograph sitting in a car. Male participants all rated the same woman, and female participants all rated the same man. Crucially, half the participants saw the man or woman sat at the wheel of a Ford Fiesta whilst the other half saw the man or woman sat at the wheel of a Bentley Continental (worth a cool £75000, approximately, at the time of testing).

Pilot research had established that, against a blank background, the photographed man and woman were perceived as equally attractive by the opposite sex (both scoring approximately mid-way on an attractiveness scale) and also that male and female participants didn't differ from each other in the aesthetic ratings they gave to the two models of car. The stand out message from the research proper, however, is that the man was rated as significantly more attractive when he was seen sat in the Bentley rather than the Fiesta, whereas the woman's perceived attractiveness was unaffected by the car she happened to be sitting in.

This finding appears to support prior research showing that in cultures all round the world, heterosexual women are attracted to men with greater status and resources, whereas heterosexual men tend to be attracted to women who appear youthful and fertile.

'It would appear that even though recent years have witnessed dramatic increases in female ownership of prestige luxury cars, such ownership does not enhance female attractiveness, as is the case with male attractiveness,' the researchers said.

'Also,' they added, 'the results contradict the "structural powerlessness" hypothesis, i.e. the belief that as economic differences diminish men and women will become more alike, as the rise in female economic fortune has not, it would appear, emancipated them from attraction to cues that are indices of wealth and status in males.'
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Dunn, M., & Searle, R. (2010). Effect of manipulated prestige-car ownership on both sex attractiveness ratings British Journal of Psychology, 101 (1), 69-80 DOI: 10.1348/000712609X417319

Downright sexy: The contrasting effect of vertical position on the perceived attractiveness of men and women

If you're hoping to increase your online appeal to the opposite sex, you might want to consider where on the screen you place your photo. A study that's in press at Social Cognition has shown that women rate men's photos as more attractive when they're placed near the top of the screen. By contrast, men rate women's photos as more attractive when they're located near the bottom of the screen.

Brian Meier and Sarah Dionne say their finding can be understood in terms of 'embodied' or 'grounded cognition', in this case our tendency to think about abstract power in terms of physical height. Powerful people are talked about as being 'high' up in the hierarchy whereas junior staff are described as being on the 'bottom rung'. By this account, women are more attracted to men's photos at the top of the screen because this position is associated with power, whereas men are more attracted to women in the lower screen position associated with powerlessness.

This pattern of findings may sound controversial but is actually consistent with evolutionary accounts of what men and women are looking for in a potential mate. According to evolutionary psychologists, both men and women have evolved to seek partners who will maximise their chances of reproductive success. For men, this means finding a mate who is powerless in the sense of being young and faithful. Women, by contrast, are attracted to mates who are powerful in the sense of having status and resources to support and protect their offspring.

The researchers obtained their results by asking 79 heterosexual students (29 were male) to rate the attractiveness of photos of men and women located either at the top or bottom of a nineteen inch computer screen. The participants were told that the location of the photos was programmed to change so as to help maintain interest in the task.

The researchers concluded: 'These findings support evolutionary theory, reveal that grounded theory has implications for common social judgments, and illustrate how grounded theory can be used as a tool to examine predictions made by theories outside the realm of basic and fundamental cognitive processes.'

Meier and Dionne also mentioned that their results could help explain why, in even more cases than you'd expect based on sex differences in height, the man in a heterosexual couple is taller than the female. 'Height could be a cue to power and hence attractiveness,' they said.
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BP Meier, & S Dionne (2010). Downright sexy: Verticality, implicit power and attractiveness. Social Cognition, In Press.

Previous Digest posts on embodied cognition: here and here.