Cognitive processes, reasoning biases and persecutory delusions: A comparative study

• Main Author: Fraser, Janelle
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2001
• Subjects: Clinical psychology; Cognitive psychology
• ISBN: 9780355581591; 0355581590

Research regarding whether people with delusions display abnormal reasoning processes is inconsistent. Garety and her research team have found that people with delusions demonstrate a 'jump to conclusions' reasoning style. However in a series of studies involving people with persecutory delusions, Bentall and his colleagues failed to find specific abnormalities. One finding which has been reliably demonstrated is that the emotional content of material increases the tendency to make hasty decisions in both the experimental and the control groups (Dudley et al, 1997b; Young and Bentall, 1997a). This study compared people with persecutory delusions with people with panic disorder and non-patient controls on a probabilistic reasoning task. Three types of material (neutral, personality characteristics and panic related) were utilised to investigate the effect of emotional content on reasoning. Participants also completed a number of questionnaire measures to explore whether hasty decision making was associated with measures of mood or cognitive processes. The results of the reasoning task showed that there was no main effect of group. However there was a trend for the people with persecutory delusions to request the least information, and the non-patient controls to request the most. All participants requested significantly less information on the two types of emotional material, suggesting that emotional content increases haste of decision making. None of the questionnaire measures were associated with performance on the reasoning task. The questionnaire measures did however show that there were a number of similarities between the two patient groups. In addition aspects of metacognition were found to be associated with ratings of delusions. The results of this study are discussed in relation to current theories of persecutory delusions and clinical and research implications are reviewed.