title: Jumping to conclusions, a lack of belief flexibility and delusional conviction in psychosis: a longitudinal investigation of the structure, frequency, and relatedness of reasoning biases.
abstract: Two reasoning biases, jumping to conclusions (JTC) and belief inflexibility, have been found to be associated with delusions. We examined these biases and their relationship with delusional conviction in a longitudinal cohort of people with schizophrenia-spectrum psychosis. We hypothesized that JTC, lack of belief flexibility, and delusional conviction would form distinct factors, and that JTC and lack of belief flexibility would predict less change in delusional conviction over time. Two hundred seventy-three patients with delusions were assessed over twelve months of a treatment trial (Garety et al., 2008). Forty-one percent of the sample had 100% conviction in their delusions, 50% showed a JTC bias, and 50%-75% showed a lack of belief flexibility. Delusional conviction, JTC, and belief flexibility formed distinct factors although conviction was negatively correlated with belief flexibility. Conviction declined slightly over the year in this established psychosis group, whereas the reasoning biases were stable. There was little evidence that reasoning predicted the slight decline in conviction. The degree to which people believe their delusions, their ability to think that they may be mistaken and to consider alternative explanations, and their hastiness in decision making are three distinct processes although belief flexibility and conviction are related. In this established psychosis sample, reasoning biases changed little in response to medication or psychological therapy. Required now is examination of these processes in psychosis groups where there is greater change in delusion conviction, as well as tests of the effects on delusions when these reasoning biases are specifically targeted.
authors.affiliation: King's College London, Institute of Psychiatry.
authors.forename: Suzanne H
authors.identifier: 0000-0001-8918-7139
authors.initials: SH
authors.lastname: So
authors.affiliation: Department of Psychiatry, University of Oxford.
authors.forename: Daniel
authors.initials: D
authors.lastname: Freeman
authors.affiliation: School of Community Based Medicine, University of Manchester.
authors.forename: Graham
authors.initials: G
authors.lastname: Dunn
authors.affiliation: Section on Schizophrenia, Imaging and Therapeutics, Institute of Psychiatry, King's College London.
authors.forename: Shitij
authors.identifier: 0000-0002-2231-2924
authors.initials: S
authors.lastname: Kapur
authors.affiliation: King's College London, Institute of Psychiatry.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kuipers
authors.affiliation: Department of Mental Health Sciences, University College London.
authors.forename: Paul
authors.identifier: 0000-0002-6030-7456
authors.initials: P
authors.lastname: Bebbington
authors.affiliation: School of Medicine, Health Policy and Practice, University of East Anglia.
authors.forename: David
authors.initials: D
authors.lastname: Fowler
authors.affiliation: King's College London, Institute of Psychiatry.
authors.forename: Philippa A
authors.identifier: 0000-0002-5637-1340
authors.initials: PA
authors.lastname: Garety
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003702:Delusions / Q000523:psychology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007600:Judgment; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011618:Psychotic Disorders / Q000523:psychology*; D013997:Time Factors; D055815:Young Adult