PhD of clinical psychology (research course)

The research in this thesis on hallucinations, with both clinical and non- clinical samples, explores the relationships between hallucinations, reality discrimination biases, suggestibility, dissociative experiences and inner speech qualities. The thesis comprises 5 studies that tested: first, the impact of suggestibility on signal detection performance (a measure of reality discrimination); second, the relationships between hallucination proneness/hallucinations, suggestibility and dissociation when and when not controlling for the confounding effects of symptoms that frequently covary with hallucinations (i.e., paranoia and depression); third, the associations between hallucinations and childhood trauma, taking into account the mediating role played by dissociative process and qualities of inner speech. The studies were conducted in the UK and Saudi Arabia, allowing a demonstration that the findings are valid cross-culturally. One main finding is that hallucination proneness and hallucinations are associated with reality discrimination deficits (i.e., signal detection biases) as reported in many previous studies, and also with suggestibility and dissociation even after controlling for comorbidity. However, the reality discrimination deficits of hallucination-prone individuals and hallucinating patients were influenced by context (suggestions). The results of the correctional analyses revealed strong relationships between hallucinations and hallucination proneness with childhood trauma, especially sexual abuse. In addition, dissociative experiences and other people in inner speech mediated this relationship. Findings from students and patients in Saudi Arabia were similar to those obtained from students and patients in the UK in previous research, and to the findings from UK students in the present series of studies. The clinical implications of the findings are discussed