Abstract
Literature comparing ‘jumping to conclusions’ (JTC) between patients and healthy controls has demonstrated the importance of the reasoning bias in the development of delusions. When groups that vary along the entire delusional continuum are included, the relationship between JTC and delusionality is less clear. This study compared JTC and delusional dimensions between 28 patients with delusions, 35 delusion-prone individuals and 32 non-delusion-prone individuals. Delusion proneness was defined by an established threshold based on the Peters et al. Delusions Inventory. Two versions of the beads task (85:15 and 60:40) were used to measure JTC. As hypothesized, patients manifested hastier data gathering than the two non-clinical groups on both beads tasks. However, delusion-prone individuals did not manifest a hastier decision making style than non-delusion prone individuals. Instead, non-delusion-prone participants showed more JTC bias than delusion-prone individuals on the easier beads task. There was no evidence for a dose-response relationship between JTC and delusional dimensions, with correlations between JTC and PDI scores found in the non-delusion-prone group only. The present finding confirms the link between an extreme JTC bias and the presence of clinical delusions, and argues against a linear relationship between JTC and delusionality along the symptomatic continuum.
Highlights
‘Jumping to conclusions’ (JTC) reasoning bias refers to a tendency to make decisions based on insufficient information in ambiguous situations [1]
Studies reported that jumping to conclusions (JTC) is found in 70% of individuals with delusions, and this hasty decision making style has been theorised as a predisposing factor for the development of delusions
In order to examine the relationship between reasoning bias and delusional dimensions, we included in this study all the original Peters et al Delusions Inventory (PDI) measures as well as average levels of conviction, distress, and preoccupation
Summary
‘Jumping to conclusions’ (JTC) reasoning bias refers to a tendency to make decisions based on insufficient information in ambiguous situations [1]. A potentially more robust design to investigate the link between JTC and delusionality would be studies that encompass the full symptomatic continuum, comparing patients, individuals with high delusion proneness and individuals with low delusion proneness This design allows for (i) comparison of JTC bias across clinical and non-clinical groups varying on delusionality, and (ii) investigation of dose-response relationship between JTC and severity of delusions across groups. Van Dael et al [27] reported a graded difference in JTC across groups, with the highest proportion of patients giving a definite rating after seeing only one bead on the beads task, followed by the delusion-prone group and the non-delusion-prone group. Key hypotheses were as follows: 1. on the easier (85:15) beads task, the number of beads drawn to decision will be the smallest in the clinical group, followed by the delusion-prone group, and the non-delusionprone group; 2. on the harder (60:40) beads task, the number of beads drawn to decision will be the smallest in the clinical group, followed by the delusion-prone group, and the non-delusionprone group; 3. there will be a stronger association between data gathering and PDI scores in the clinical group than the non-clinical groups
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