Author's personal copy Change in delusions is associated with change in “jumping to conclusions” Todd S. Woodward a,b, ⁎, Manuel Munz c , Claude LeClerc d , Tania Lecomte e a Department of Psychiatry, University of British Columbia, Vancouver, Canada b Department of Research, BC Mental Health and Addictions Research Institute, Vancouver, Canada c Department of Psychiatry and Psychotherapy, Rostock University, Rostock, Germany d Département des Sciences Infirmières, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada e Département de Psychologie, Université de Montréal, Montréal, QC, Canada abstract article info Article history: Received 8 February 2008 Received in revised form 26 August 2008 Accepted 23 October 2008 Keywords: Delusions Schizophrenia Reasoning Evidence has been put forward that premature termination of data collection and jumping to conclusions behavior (JTC) is associated with delusions. However, few investigations have attempted to track associations between changes in delusions and changes in JTC measures. In the current study individuals with schizophrenia spectrum disorders completed a version of the JTC task (involving fishing from lakes as opposed to drawing beads from a jar) at two timepoints 12 weeks apart. The results revealed significant negative correlations between change in task performance (number of requested pieces of information) and change in delusion scores over time. This evidence is consistent with the contention that the JTC task is sensitive to the cognitive systems underlying delusions in schizophrenia spectrum disorders. © 2008 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Delusions are consensually defined as fixed false beliefs not amenable to contrary evidence, and are hallmark symptoms of schizophrenia spectrum disorders. Although it was initially proposed that delusional ideation cannot be explained by a pathology of reasoning (Maher, 1988), recent work has revealed a number of aberrations in reasoning in individuals with schizophrenia with current or past delusional ideas (Bell et al., 2006; Blackwood et al., 2001; Davies et al., 2001; Garety and Freeman, 1999). One of the most commonly studied reasoning paradigms is known as the jumping to conclusions (JTC; Garety et al., 1991; Huq et al., 1988) paradigm, and is widely cited and reviewed (Bell et al., 2006; Blackwood et al., 2001; Davies et al., 2001; Garety and Freeman, 1999). JTC paradigms typically involve the beads task, where the subject is presented with jars containing beads of two colours (e.g., black and white beads divided 60–40 in one jar and 40–60 in the other) and are asked from which jar beads are being drawn when the jars have been hidden from view. Individuals with schizophrenia tend to request fewer beads before deciding on which jar is the source of the beads (draws-to-decision procedure). The dominant interpretation of this finding is that individuals with schizophrenia display a data gathering bias, in that they seek less information before reaching a decision (Garety and Freeman, 1999). However, the literature on whether or not JTC correlates with delusions is mixed, as a JTC bias has been observed for both currently deluded and non-deluded individuals with schizophrenia (Menon et al., 2006; Moritz and Woodward, 2005), and in some studies an association with delusions is absent (McKay et al., 2007; Young and Bentall, 1997). Some studies report that the association with delusions depends on methodological variables, such as the requirement to self- terminate the trial by indicating that they have enough information to decide (Garety et al., 1991; Moritz and Woodward, 2005; van Dael et al., 2006), and/or high working memory load (i.e., the jars are hidden from view and the bead is replaced in the jar after being viewed; Menon et al., 2006). Unfortunately cross sectional studies cannot provide definitive evidence for the cognitive underpinnings of delusions, for two main reasons. First, between-group comparisons of conditions (e.g., delu- sional vs. nondelusional individuals) are less powerful than within- group comparisons, because any differences between the subjects contribute to the error term in the between-group design, but much of this source of error is subtracted out of the error term when each subject is used as his or her own control. Second, individuals currently displaying delusions may tend to possess certain characteristics that would not change if the delusions were to go into remission, such as a genetic predisposition that affects cognitive performance and/or a pre- existing cognitive style. A longitudinal study is more powerful and interpretable, because pre-existing differences between nondelusional and delusional conditions will be held constant as delusions change. Psychiatry Research 170 (2009) 124–127 ⁎ Corresponding author. Room 2N9, Detwiller Pavillion, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 1Z3. Fax: +1 604 822 7756. E-mail address: toddswoodward@gmail.com (T.S. Woodward). 0165-1781/$ – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2008.10.020 Contents lists available at ScienceDirect Psychiatry Research journal homepage: www.elsevier.com/locate/psychres