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

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 non-clinical samples (n = 2238) 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. Delusional Inventory”; PDI). We found that delusional ideation is negatively associated with data gathering (rs = -0.10, 95% CI [-0.17, -0.03]) and that there is heterogeneity in the estimated effect sizes (Q-stat p = 0.03, I2 = 33). Subgroup analysis revealed that the negative association was present when considering the 23 samples (n = 1754) drawn from the large general population subgroup alone (rs = -0.10, 95% CI [-0.18, -0.02]) but not the eight samples (n = 263) drawn from the much smaller current delusions subgroup alone (rs = -0.13, 95% CI [-0.33, 0.06]). These results provide some provisional support for continuum theories of psychosis and for cognitive models that implicate the JTC bias in the formation and maintenance of delusions.