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Schizophrenia Research and Treatment
Volume 2012 (2012), Article ID 384039, 9 pages
Research Article

Jumping to Conclusions Is Associated with Paranoia but Not General Suspiciousness: A Comparison of Two Versions of the Probabilistic Reasoning Paradigm

1Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
2Department of Management and Economics, Kuehne Logistics University, Hamburg, Germany
3Department of Psychology, University of Hamburg, Hamburg, Germany

Received 6 August 2012; Accepted 12 September 2012

Academic Editor: Robin Emsley

Copyright © 2012 Steffen Moritz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Theoretical models ascribe jumping to conclusions (JTCs) a prominent role in the pathogenesis of paranoia. While many earlier studies corroborated this account, some newer investigations have found no or only small associations of the JTC bias with paranoid symptoms. The present study examined whether these inconsistencies in part reflect methodological differences across studies. The study was built upon the psychometric high-risk paradigm. A total of 1899 subjects from the general population took part in an online survey and were administered the Paranoia Checklist as well as one of two different variants of the probabilistic reasoning task: one variant with a traditional instruction (a) and one novel variant that combines probability estimates with decision judgments (b). Factor analysis of the Paranoia Checklist yielded an unspecific suspiciousness factor and a psychotic paranoia factor. The latter was significantly associated with scores indicating hasty decision making. Subjects scoring two standard deviations above the mean of the Paranoia Checklist showed an abnormal data-gathering style relative to subjects with normal scores. Findings suggest that the so-called decision threshold parameter is more sensitive than the conventional JTC index. For future research the specific contents of paranoid beliefs deserve more consideration in the investigation of decision making in schizophrenia as JTC seems to be associated with core psychosis-prone features of paranoia only.