How accurately do humans identify biological sex?

There has been only one case when I have been unable to discern someone's sex.

The last time was in a hotel. Another guest was checking in as I was in the lobby waiting for a taxi. The person was quite striking-looking: I am guessing the person was Japanese, had long hair and was wearing a man's dark suit, a white dress shirt and brogues. They were turned at an angle to me so I couldn't see any more physical characteristics and I didn't hear them speak.

I remember this clearly as the person was so beautiful - his / her face was just gorgeous and the gender ambiguity made them even more eye-catching.

Several times on public transportation I have seen women who look / dress very androgynously but they still were markedly female.

That uncanny Valley link is really interesting. Personally I think we just feel slightly tricked, plus the natural wariness of someone who doesn't seem like yourself

I have worked with a couple of adults where I couldn’t actually have called their gender. Neither were trans but I genuinely do live in an area with a lot of genetic issues due to a history of in breeding. This is not to infer that being trans is a genetic issue or due to inbreeding.

One person I worked quite closely with and other colleagues would often misgender him. Thankfully he had a very male name so there could be no ambiguity.

Why would there be too many variables to do research looking at whether individuals correctly identify sex? Fundamentally there is only one variable of interest. Of course people are diverse and present in many different ways but apart from children pre puberty or those who deliberately work to disguise their presentation (which may or may not include hormones or surgery) it is unusual not to be able to correctly identify someone's sex after spending any time with them. I would expect this to be even more the case in situations in heightened risk or when people are on the pull.

Uncanny valley! That's fascinating but also sets nerves jangling:

en.wikipedia.org/wiki/Uncanny_valley

It is hard wired into our brains to realise very quickly when something is either not as it first seems or is close to human but not quite (I feel this with ventriloquist dummies!).

It’s called “uncanny valley” and is usually used to express the disquiet experienced faced with e.g. extremely human like robots or gorillas when they use human expressions.

Disclaimer - I am in no way making any comment on trans people not being human before anyone twists my words. The phrase is now widely used outside the robotic community.

spent £££s on* facial feminisation

My 10 year old DS walked in when I was watching Munroe Bergdorf being interviewed by Andrew Neil

He studied the screen for maybe 10 seconds, and said "He must spend a lot of time on his hair”

Interesting. My DP said, on seeing MB on the genderquake debate “well what’s she got to do with anything?” I also wasn’t sure, so googled her and was surprised to see she was trans until she opened her mouth However when I found out she’d spent £££s no facial feminisation surgery I guess that makes sense.

I think in the natural world without make up and very gendered clothing I’d be 95% accurate at guessing sex. There are a few androgynous types that don’t fit into either category neatly, but like other posters, I reckon one sniff of their armpits and I’d know!

I also have good gaydar - have never found any the famous men who have since come out attractive, always preferred Andrew Ridgley to George Michael in their Wham days! My DP says I’m the most heterosexual person he’s ever known though, I am very turned on by all the markers of maleness, love the smell of him all over and love body hair, even back hair so maybe I am hypersensitive to these things?

OK terfs up I will do research elsewhere as I am annoying you. You're just not very clear when I am giving an example of other research which I assumed was fairly standard with hundreds of variables and thousands of participants. Nothing you're saying makes sense to me.

My poor GF. Being maligned on MN

My DGF's was aggressive to men and the only woman he ever went for was wearing her boyfriends jumper.

This is my favourite post on MN today. Thanks MrsTerryPratchett!

Oh, FFS. For the third time, there are too many variables to account for. The number of participants is not the same as the number of variables.

But the other research had hundreds. I don't see why this one is so different

Terfs research has been done to assess the many factors in early years and the impact on educational outcomes. Surely that's of the same level?

Nope. As I said, there are too many variables.

Dog. Not my DGF, he was a very nice man!!!

There's a study that had women smell a t-shirt and decide if the person was attractive to them. Screw height and Adam's apples, I'm fairly sure that I could tell blindfolded if I got to sniff an unperfumed neck .

My DGF's was aggressive to men and the only woman he ever went for was wearing her boyfriends jumper.

I have no problems telling which sex someone is.

I knew a transwoman in passing in childhood, they lived near me. I remember questioning it all with my Mum, when the transwoman was out of earshot. I remember I was fascinated by them as a child, how they moved mostly. I remember they always seemed so sad and my safety instinct was on high alert.

My 10 year old DS walked in when I was watching Munroe Bergdorf being interviewed by Andrew Neil

He studied the screen for maybe 10 seconds, and said "He must spend a lot of time on his hair"

Terfs research has been done to assess the many factors in early years and the impact on educational outcomes. Surely that's of the same level?

I think tbh the only time you genuinely can't tell with adults are when the individual is very severely under or over weight and dressed in baggy clothing. That masks secondary sexual characteristics, and a lot of fat around the face can mask jaw lines and potential Adams apple, while being very severely under weight also makes the bone structure look unfamiliar and females lack the differentiating curvier blunting of edges which a woman with enough body fat to menstruate has at a healthy weight.

Even then it's usually clear which sex someone is. But those are the only body shapes that sometimes mask biological sex, and even then of course only in combination with being covered up in baggy shapeless gender neutral clothes.

With children pre puberty you can't necessarily tell if hair and clothes are the same, but prepuberty that's unsurprising as most of the differences aside from actual genitals and chromosomes only manifest at puberty.

Does anyone remember a short series shown on Channel 4 about 18 or so years ago when a small group of men and were in their 20s were asked to dress up and try to 'pass' as people of the opposite sex?

The 'winner' was a man. Going by a very hazy memory - he was Brazilian, named Pablo, had a short, slight-ish build and was a student at the then-named Thames Valley University (now University of West London). The women were the first to be 'unmasked'.

Nauticant, that made me laugh!

Why would like sort of research be more complex than other similar types of research?

There are too many variables: height, weight, build, age and race being just the ones that I can think of off-hand.

In general, hands are a dead giveaway unless the trans woman is very small. Funnily enough a lot of trans women seem to be pretty big - even for blokes.

This might be relevant, it's unclear whether it's ongoing: opl.apa.org/Experiments/About/AboutGenderPerception.aspx

Nauticant they probably say the same about humans!