Schizotypy: A Multi-Country Study of Psychometrics, Socio-Cultural Influences, Cognitive Processes, and Electrophysiological Markers

Schizotypy represents a latent personality organisation reflecting a putative liability for schizophrenia spectrum disorders. Schizotypic traits include anomalies in cognition (e.g., hallucinations), socio-emotional function (e.g., constricted affect), and behaviour (e.g., odd behaviour and language) that do not meet the clinical threshold for psychotic disorders. This thesis presents a series of studies investigating schizotypal measurement across ethno-cultural settings, examining cognitive antecedents and outcomes of schizotypy, and a schizotypal-continuum exploration into electrophysiological function.

Studies 1-3 examined the Schizotypal Personality Questionnaire (SPQ) as a measurement tool for schizotypy. These studies re-evaluated the domain structure of the English SPQ and the German SPQ, and developed and evaluated a Malay translation of the SPQ. Further, through the evaluation and development of these measures, schizotypy was explored within the framework of ethnic and cultural identities. This included evaluations between African Caribbeans in the UK and Trinidad, with White British participants; Malay and Chinese participants in Malaysia, and; central European White participants from Austria and southern Germany, with a similar cultural (migrational) group in the UK.

Studies 4a and 4b concerned schizotypy, cognitive processes, and conspiracy ideation. From an initial pilot, associations were established with conspiracy ideation, included as a prima facie outcome of disordered thinking. A follow-up study showed that analytic thinking mediated the relationship between Odd Beliefs or Magical Thinking (but not Ideas of Reference) and belief in conspiracy theories. Study 5 investigated whether a combination of high schizotypal ratings and abnormal electrophysiological function could be established. Second, this study allowed for a unique comparison between culture and ethnicity, within the assessment of electrophysiological function. Finally, this study allowed for an investigation into associations between the domains established in Study 1 (namely, Cognitive-Perceptual, Paranoid, Disorganised, and Negative) and electrophysiological function. Results indicated little evidence of association between the schizotypy and schizophrenia literature; that is, there was no apparent electrophysiological deficits for high schizotypal individuals and no ethno-cultural influence. Further, the results of the regression indicated no support for associations at the higher-order domain level and electrophysiological function.

Taken together, these studies informed the schizotypal literature through multiple routes. Indeed, this thesis addressed both the personality (cognitive outcomes) and clinical (electrophysiological) nature of schizotypy with the foundation of a thorough measurement examination.