This is a great point. I'm did read an article, by someone who is autistic, who more or less said that the face tests are rubbish for precisely that reason.
It is that autisctic people can read the faces but recognise that the emotions on the faces can be more complex.
I they try and interprate an array of complex reasons which is interpreted as being slow at reading faces.
Whereas an NT will join in and play the simple 'face' game.
There may be a different reason why there is this 'we don't understand faces'
More to do with being misunderstood
As they may not understood how we may approach the test.
Let me find this article.
“Michelle Dawson on Autism and Atypicality (Ep. 46)” @mercatus https://medium.com/conversations-with-tyler/tyler-cowen-michelle-dawson-autism-research-dsm-f2a41b326e76
It's a super long read, so do a Ctrl f and type face..
I Amy copy past a few bits in.
Here's some of the text re the face test -
Cowen :
Is the following a fair description? Let’s say that many autistics are taking in more information than would be typical. So sometimes those autistics will end up confused, or they will feel confused or act as if they appear they’re confused
But other times, if they develop procedures for processing that information — rules — they become better at interpreting the information. Maybe they have to become better because they face this more difficult task. So, you will have autistics show unusual mastery of social situations. Even if they appear awkward, they’ll see much more detail than nonautistics would in some cases.
Dawson
Well, there’s a huge literature in autism about how autistics judge facial expressions of emotion in other people. And what you have in the autism literature is, you haven’t only just turned autistic people into stereotypes and cartoons, you’ve done that to the typical population.
This is really at odds with the nonautism literature on facial expressions, which is much more complicated. In the autism literature, it’s assumed that you can just read people’s inner emotions and mental states. Mental states are not necessarily well defined, that it’s a simple matter, that it is sort of written all over somebody’s face, or even you can read it just from looking at a photo of their eyes.
And things are far more complicated than that in the literature, in the nonautism literature. For example, MIT — their affective computing group, Rosalind Picard did these fantastic studies showing that people smile in frustration, and those are real honest-to-goodness Ekman-type smiles. You have the whole facial action coding thing going on. Those are real, genuine smiles that people smile in frustration when they are genuinely frustrated. They don’t do it when they’re acting out frustration. And there are many other examples like that.
People smile for many different reasons, and that is acknowledged to some degree in the literature in the typical population, not in the autism literature, where things are completely simple. They’re just very caricatured and cartoonish. Now, what you find is that the typical population can decipher their way through this. They know what these facial expressions are supposed to represent, even if they don’t look like that in real life.
Autistics are — maybe because their experiences are quite complex with how people respond to them starting early in life, and I’m just wildly speculating here — but autistics are going to notice that things are more complex and uncertain than that. Again, it’s the considering more possibilities, and that will very much hamper their task performance if what you are looking for is this automatic certainty that these acted expressions are all there is, which is not accurate.
And that leads to many problems because we’re actually training autistic people to ignore the complex, real, important information in favor of the caricatured, stereotyped, simplified, probably wrong information, and we should really think about that. But that gives you an idea of looking at social deficits, thinking about how autistics process information, and also actually looking at the literature itself.