This focus on group differences is an example of what psychologists call “known-group” validity evidence, where the ability of test scores to discriminate between groups that are known to differ on a particular psychological attribute supports the interpretation that the test scores measure that attribute.

But this known-group validity evidence is problematic for at least two reasons. First, studies do not always find that autistic people score lower on the Eyes Test. Even in cases where scores are lower, there are viable alternative explanations that have not been ruled out. For example, some autistic people find eye contact extremely uncomfortable and thus might find doing the Eyes Test aversive.

The second problem with this known-group validity evidence is circularity. Autistic people’s poor performance on the Eyes Test is used to support the validity of the Eyes Test as a measure of theory-of-mind ability and is key evidence for the theory-of-mind deficit account of autism.

The issue of circularity is common in the construction of psychological tests.