I'm not sure I used the right words. What I mean is that practically all of these tests that purport to show that autistic people can't read facial expressions, don't test this in a realistic way. They will generally include things like (one or more of):
Forcing the person to use/understand words during the test.
Using actors rather than genuine situational facial expressions. This can mean that the test is a test of familiarity with cultural stage conventions more than anything else.
Choosing to represent which is the right answer by determining how a certain number of nonautistic people interpret the expression, with no way of telling whether those people are right or wrong. (One of the weirdest ones I ever saw was interpreting an expression as "desire" when it looked like an expression that would CAUSE desire in the viewer if they were straight and male, but not necessarily conveying desire in the person whose face it was.)
Taking the faces out of magazines and other situations that make it hard to verify what the expressions were.
Limiting faces and expressions to only one culture/ethnicity regardless of culture/ethnicity of the people being tested.
Using cartoons or line drawings that don't represent actual features of a face (for instance real smiles and cartoon smiles look different) and/or that use cartoon-style conventions that defy reality.
Making changes to the presentation of the face that differ from how things would happen in real life, for instance:
* Cropping the face to show a smaller piece of the face than would be visible in most real life situations.
* Making the face black and white or otherwise altering the coloring.
* Using stills rather than moving video.
* Flashing an expression for an abnormally short period of time, and without the natural progression of the physical movement of the face.
* Many others I don't remember this instant.
Testing only certain sorts of autistic people then generalizing the results to all of us.
Or worse in some ways, using common assumptions of severity when generalizing to all of us. For instance, testing people who can speak, understand spoken language, read, and write. Then assuming that not only do these results apply to people who can't do more than one of these things, but that these results apply more severely to people who can't do one or more of these things. So if speaking/literate/etc. people can't read the expressions then nonspeaking people or people with limited language comprehension must have even more severe trouble reading expressions.
Testing autistic people while they are in one particular mode and assuming it applies to them in other modes. For instance testing autistic people in a mode that forces them to use language then assuming that the same results apply to them when they can't understand language.
Assuming that when autistic people perform worse than nonautistic people on these tests, it means autistic people must perform worse than nonautistic people in reading facial expressions in real life. (Assuming that the test represents ability to read genuine facial expressions in natural situations.)
Assuming that the test shows not only abilities to read facial expressions, but body language in general, or worse, all nonverbal cues in general.
Testing only for typical face/body language reading abilities, not for the atypical body language reading that many autistic people describe in ourselves. Often done because the testers have never heard of the ways some autistic people can read other people. It's hard to test abilities that you don't even know exist.
And many more flaws, all at once adding up to a situation where what the test really measures and what it claims to measure are totally different things. Add all those things together and you have a situation where you can't even tell what you're measuring, if anything. So many things are potentially wrong, that you can't even tell what they are. And that's besides the ones I wasn't able to write down here.
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"In my world it's a place of patterns and feel. In my world it's a haven for what is real. It's my world, nobody can steal it, but people like me, we live in the shadows." -Donna Williams