I wanted to replicate this result myself. So a few months ago, when I surveyed readers of my blog, I included some questions about perceptual illusions (including a static version of the hollow mask). I got five thousand responses, including a few from schizophrenic and autistic readers. Sure enough, the effect was there.
Schizophrenic readers were about twice as likely to report a weak reaction to the mask illusion as non-schizophrenics (28% vs. 14%, p = 0.04). They were also more likely to have a weak reaction to a similar illusion, the Spinning Dancer (58% vs. 81%, p = 0.01). Readers with a family history of schizophrenia landed in between schizophrenics and healthy controls (16% for mask, 63% for dancer, ns).
Autistic readers were only slightly more likely to report a weak reaction to the mask illusion than neurotypicals (17% vs. 14%), but thanks to our big sample size we could be pretty confident that this was a meaningful difference (p = 0.004). There was no different between autists and neurotypicals on the Spinning Dancer, not even a weak trend (58% vs. 60%, p = 0.4).
Looking deeper, I found a few other anomalies on illusion perception. Most were small and inconsistent. But one stood out: transgender people had an altered response pattern on both illusions, stronger than the alteration for autism and almost as strong as the one for schizophrenia (mask: cis 14% vs. trans 21%, p = 0.003; dancer: cis 58% vs. trans 71%, p = 0.001). These results are very tentative, and need replication. My mass survey isn’t a very sensitive instrument, and I place low confidence in any of this until other people can confirm.