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

Robert Ross, Ryan McKay, Max Coltheart, Robyn Langdon

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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 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.
Original languageEnglish
Pages (from-to)1183-1191
Number of pages9
JournalSchizophrenia bulletin
Issue number5
Early online date22 Jan 2015
Publication statusPublished - Sept 2015


  • bias
  • beads task
  • delusion
  • jumping to conclusions
  • meta-analysis
  • schizophrenia

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