Pickup, Graham John; (1997) Representation of mental states in schizophrenia. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

From a literature review, it was concluded that schizophrenia primarily involves deficits in conscious, controlled processing. This was shown to be compatible with Frith's (1992) neuropsychological model of impaired meta-representation in the disorder. There is strong evidence that patients with paranoid symptoms or behavioural signs have deficits in the representation of others' mental states ('theory of mind'; ToM), but two recent studies have produced conflicting results. Those findings were reconciled in the first study of the thesis, which showed that, on false belief tasks, patients have intact first-order ToM, but specific impairments at the second-order level. This was later confirmed using a 'hints' test of ToM. The results were contrasted with the case of autism. On a spatial reversal test of executive function, schizophrenics with behavioural signs made more perseverative errors than controls. No correlations appeared between ToM and executive function for any of the schizophrenic symptom groups. This was contrasted with the case of autism, and it was suggested that schizophrenia involves late-occurring, independent deficits in separate metarepresentational domains. It was argued that Frith's model of schizophrenia can be extended to include impaired representation of own knowledge, explaining the deficient use of context in the disorder. Some evidence was obtained that patients with primarily behavioural signs are impaired at naming objects in a picture context; this ability was unrelated to ToM, consistent with independent deficits in separate metarepresentational domains. It was suggested that 'weak central coherence' in autism may also reflect impaired representation of own knowledge, and some evidence was obtained that (like autistics), symptomatic schizophrenics show facilitation on embedded figures tests. Schizophrenic patients performed the same as controls, however, on an illusions task. For patients with behavioural signs, embedded figures accuracy was inversely related to the ability to name objects in a picture context, and it was argued that this supported task analyses suggesting a common cognitive process.

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