Biased interpretation in paranoia and paranoid psychosis

Student thesis: Doctoral ThesisDoctor of Philosophy


There is now considerable evidence showing pathology congruent cognitive biases in the interpretation of emotionally ambiguous information. Such biases selectively prioritise the processing of information that can confirm a pathological belief and thereby play a direct role in maintaining associated pathology. Although interpretation biases are well documented in the affective disorders, little work has been done in other psychopathologies, including psychosis. This thesis reports five studies investigating the degree to which pathology congruent interpretation biases are present in paranoia and paranoid psychosis. Chapter 1 introduces the literature on biased cognition in paranoia and paranoid psychosis. Chapter 2 (Experiment 1, n = 70) provides an evidence base for the interpretation biases relevant to paranoid thinking and identifies their level of content specificity in the non-clinical population. Chapter 3 (Experiment 2, n = 70) investigates the hierarchy and severity of paranoid thinking in the non-clinical population. Chapter 4 (Experiment 3, n = 90) validates the most sensitive measures of interpretation and reasoning biases in a clinical sample characterised by paranoid and non-paranoid psychosis. Chapter 5 (Experiment 4, n = 138) tests the prediction of interpretation biases on paranoid thinking and anomalous perceptions. Chapter 6 (Experiment 5, n = 60) tests the effectiveness of a novel ‘Cognitive Bias Modification’ for psychosis programme for use in the reduction of paranoid interpretations. Chapter 7 discusses findings in the context of the wider literature and in relation to existing cognitive models of psychosis. Results from this thesis demonstrate evidence that paranoid and valenced interpretation biases are associated with higher levels of trait paranoia. Individuals with higher levels of trait paranoia are also shown to make less non-paranoid interpretations of emotionally ambiguous information than individuals with lower levels of trait paranoia. Interpretation is an underlying cognitive process that, when biased in a paranoid direction, has the potential to contribute toward maintaining a paranoid psychotic state.
Date of Award2013
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorJenny Yiend (Supervisor) & Sukhi Shergill (Supervisor)

Cite this