Jumping to perceptions and to conclusions: Specificity to hallucinations and delusions

Background: There is evidence that people with psychosis display a "jump-to-conclusions" (JTC) reasoning style, and that this bias may be specific to delusions. A "jump-to-perceptions" (JTP) cognitive bias has also been found and is typically linked to hallucinations. However, there is some evidence for an association between JTP and delusions, and its specificity to hallucinations remains unclear. It has been suggested that these biases are related and products of shared cognitive processes. Methods: This study examined the symptom specificity of JTC and JTP, and the relationship between them, in a sample of 98 individuals with delusions divided into 'hallucinators' (n = 51) and 'non-hallucinators' (n = 47). Biases were assessed using the beads task and visual and auditory perceptual tasks. Results: As predicted, both groups demonstrated a JTC bias, but the 'hallucinators' showed a more pronounced JTP style in both modalities. The presence of JTC and JTP biases did not co-occur: making a decision on the beads task after two or fewer draws was not related to visual JTP, and was associated with a less marked JTP bias in the auditory perceptual task. No differences were found in JTP or JTC between participants with and without a schizophrenia diagnosis. JTP, but not JTC, was associated with the presence of hallucinations. Conclusions: These findings suggest that the JTC and JTP biases show specificity to delusions and hallucinations, respectively, and not to diagnosis. There was no evidence that they are the product of shared cognitive processes, further supporting their specificity. (C) 2014 Elsevier B. V. All rights reserved.