Problems in measuring the JTC-bias in patients with psychotic disorders with the fish task: A secondary analysis of a baseline assessment of a randomized controlled trial

Abstract

Background: The jumping to conclusions bias (JTC) is considered to be an important causal factor in theoretical models on the formation and maintenance of delusions. However, recent meta-analytic findings show a rather equivocal pattern of results regarding associations between JTC and delusions. Thus, the aim of the present preregistered study is to investigate in a large sample whether the JTC-bias is more pronounced in patients with psychotic disorders in comparison to controls and whether the JTC bias is associated with more severe delusional conviction, persecutory delusions and positive symptoms in general. Methods: Patients with psychotic disorders (n = 300) enrolled in a therapy trial and healthy controls (n = 51) conducted a variant of the beads task (fish task) as a measure for the JTC-bias at start of the trial. Further, clinical interviews were used to assess patients' delusional severity and delusional conviction. Results: There were no statistically significant differences between patients with psychotic disorders (with 53% displaying the JTC-bias) and controls (41%). Furthermore, there were no statistically significant correlations between JTC measures and persecutory delusions, delusional conviction and positive symptoms. Conclusions: We found no evidence for hasty decisions in patients with psychotic disorders, which is in part in line with meta-analytic findings using a wide range of JTC task variants. However, the task variant we used in the present study (fish task) is discussed as potential reason for the non-significance of our results, as it may induce a more deliberative reasoning style as compared to the traditional beads task. Furthermore, possible implications for the measurement of the JTC-bias in general are discussed. Trial Registration: ISRCTN29242879 (isrctn.com), date of registration: April 12th 2006

Unstable Belief Formation and Slowed Decision-making: Evidence That the Jumping-to-Conclusions Bias in Schizophrenia Is Not Linked to Impulsive Decision-making

“…Patients with SCZ consistently show JTC 1,4,11 and over-estimate the probability that the beads are drawn from a specific jar 9,10,[12][13][14] . However, the reasons for this bias remain unclear 1,4,11,[15][16][17][18] . On the one hand, JTC has been associated with delusions 1-4, 11, 19-23 and impulsive decision-making 1,2,22,24 .…”

“…On the one hand, JTC has been associated with delusions 1-4, 11, 19-23 and impulsive decision-making 1,2,22,24 . On the other hand, a growing number of studies have shown that patients with SCZ display JTC even without the presence of delusions and other authors have attributed JTC to impaired probabilistic reasoning 10,11,16,18,[25][26][27] . Specifically, patients seem to overweight unexpected recent bead occurrences -leading to unstable beliefs about the correct source jar 9,12,15,17,28 .…”