Jumping to Conclusions About the Beads Task? A Meta-analysis of Delusional Ideation and Data-Gathering

Abstract

It has been claimed that delusional and delusion-prone individuals have a tendency to gather less data before forming beliefs. Most of the evidence for this "jumping to conclusions" (JTC) bias comes from studies using the "beads task" data-gathering paradigm. However, the evidence for the JTC bias is mixed. We conducted a random-effects meta-analysis of individual participant data from 38 clinical and nonclinical samples (n = 2,237) to investigate the relationship between data gathering in the beads task (using the "draws to decision" measure) and delusional ideation (as indexed by the "Peters et al Delusions Inventory"; PDI). We found that delusional ideation is negatively associated with data gathering (r(s) = -0.10, 95% CI [-0.17, -0.03]) and that there is heterogeneity in the estimated effect sizes (Q-stat P = .03, I(2) = 33). Subgroup analysis revealed that the negative association is present when considering the 23 samples (n = 1,754) from the large general population subgroup alone (r(s) = -0.10, 95% CI [-0.18, -0.02]) but not when considering the 8 samples (n = 262) from the small current delusions subgroup alone (r(s) = -0.12, 95% CI [-0.31, 0.07]). These results provide some provisional support for continuum theories of psychosis and cognitive models that implicate the JTC bias in the formation and maintenance of delusions.

Keywords: beads task; bias; delusion; jumping to conclusions; meta-analysis; schizophrenia.

Fig. 1.

Forest plot of random effects meta-analysis showing effect sizes (r _s) for the association between draws to decision and Peters et al Delusions Inventory. The black squares show effect sizes for each sample and are drawn proportional to the relative weighting of each sample in the analysis. The error bars show the 95% CI for each sample. The dark gray diamond shows the overall 95% CI. The light gray diamonds show the 95% CI for each subgroup. The broken line shows the overall mean effect size estimate.

Fig. 2.

Regression plot showing the random-effects meta-regression examining the relationship between number of beads task trials and effect sizes. Effect sizes (r _s) are plotted as circles with the size of the circles drawn proportional to the relative weight of the sample in the analysis.

Fig. 3.

Funnel plot showing effect size (r _s) plotted against standard error.