The imprinted brain theory is unique in many ways, not least that in which it stands on two completely different foundations: one in evolution and genetics, and one in psychiatry and cognitive science. In a previous post I noted a recent finding in genetics which endorsed its distinctive, diametric model of mental illness, and here I report the first laboratory study to test its prediction that basic cognitive processing is diametrically different on each side of the autism/psychosis divide.

In another recent post, I pointed out that you could use measures like the Autism Quotient (AQ) to place people on the continuum which, according to the diametric model of the mind, stretches all the way from autism at one end to psychosis at the other. A measure appropriate for evaluating tendencies towards the psychotic end of the spectrum is the Unusual Experiences subscale of the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE:UE). This can be used to assess so-called schizotypy, or mild schizophrenic tendencies, and so can be regarded as something of an equivalent to AQ.

A team of researchers in Australia writing in The Journal of Autism and Developmental Disorders, report that they obtained the AQ and O-LIFE:UE scores of 318 students. From these, two pairs of groups (i.e. four groups in total) were formed, each with 20 participants: High and Low AQ groups and High and Low O-LIFE:UE groups. The AQ groups were matched on schizotypy traits but were selected to differ substantially in autistic ones, while the O-LIFE:UE groups were matched the other way round: similar for autistic traits but different for schizotypy. The researchers reasoned that the diametric model of cognition predicts that the High AQ group would be faster to detect embedded figures in the Embedded Figures Test (EFT) than the Low AQ group, while the High O-LIFE:UE group would be slower to detect the embedded figures than the Low O-LIFE:UE group.

This is because detecting hidden figures involves ignoring the overall gestalt of the image in which they are concealed and decomposing it into its parts. This is something at which autistics often excel, and could be seen as the reverse side of their deficit where seeing things in their wider context is concerned. Correspondingly, people with a more global, top-down and contextual style of cognition like that usually found in those with better-developed—or over-developed—mentalistic skills ought to find such hidden figures more difficult to detect. For them, noticing the independent detail in the wider picture is the deficit.

The authors report that “individuals with high levels of autistic-like traits showed more skilled performance on the EFT than individuals with few autistic-like traits, consistent with a preference or advantage for local over global processing. In contrast, individuals with high levels of positive schizotypy traits showed less skilled performance on the EFT than individuals with low levels of these traits, consistent with a preference or advantage for global over local processing. Therefore, these results offer support for Crespi and Badcock’s claim that autistic and positive schizophrenia traits are diametrically opposed with regard to their effect on local versus global processing.”

Verbal and non-verbal IQ was also tested, but although the High O-LIFE:UE group did have somewhat lower non-verbal ability than the Low O-LIFE:UE group as predicted by the theory, the difference was not statistically significant, and contrary to predictions of the theory, no effect was found for the High/Low AQ groups. However, the authors point out that the use of a student sample may have led to a restriction in the range of IQ scores, particularly with reference to verbal IQ (and it is worth adding that the preponderance of female subjects in the study might be expected to have the same result). The authors conclude that a more powerful test of this aspect of the theory using larger, community-based samples is warranted. Watch this space.  

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