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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.
Ross et al. (Thu,) studied this question.