Predictive processing and source monitoring in the psychosis continuum

• Main Author: Humpston, Clara
• Published: Cardiff University 2017
• Subjects: BF Psychology
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.732274

Schizophrenia is a serious and debilitating mental illness, and sufferers frequently experience a multitude of symptoms. Of particular interest to the current Thesis are psychotic symptoms including delusions, hallucinations and associated self- disturbances such as interference in the agency and ownership of thoughts and actions. Since the disorder was first described over a century ago, research into the pathogenesis of schizophrenia has advanced greatly. However, there are still large gaps in the current knowledge and understanding of the neuropsychological bases of this devastating illness. The current Thesis adopts a cognitive neuropsychiatric approach and applies a continuum model to the construct of psychosis. The aim of the current Thesis was to incorporate theories such as the source monitoring and the predictive processing frameworks across a range of behavioural tasks, in order to investigate some of the neuropsychological deficits in schizotypy and early psychotic symptoms. Healthy individuals with schizotypal traits and patients with early psychosis who did not yet meet a full diagnosis of schizophrenia underwent a battery of behavioural paradigms, with each task aimed at a different aspect of predictive processing and source monitoring. In healthy individuals, nonclinical psychosis-like experiences measured with schizotypy scales were significantly associated with difficulties in the source monitoring of actions, in particular deficits in reality monitoring and internal source monitoring. However, no significant relationships were found for the predictive processing tasks, which focused on the perceptual (force-matching), associative (Kamin blocking) and motivational (reversal learning) domains. In the patients with first episode psychosis, positive psychotic symptoms were not significantly correlated with specific deficits in either category of tasks, although this study was under- powered and strong conclusion could not be drawn. Nevertheless, these findings have provided support for partial dimensionality in psychosis vulnerability and will serve as foundations for future research on a larger scale.