- Email: [email protected]
Examining cognitive biases in patients with delusions of reference
European Psychiatry 28 (2013) 71–73
Short communication
Examining cognitive biases in patients with delusions of reference M. Menon a,*,b, J. Addington a,b,c, G. Remington a,b a b c
Schizophrenia Program & PET Centre, Centre for Addiction & Mental Health, 250 College St, Toronto M5T 1R8, Canada Department of Psychiatry, University of Toronto, Toronto, Canada Department of Psychiatry, University of Calgary, Calgary, Canada
A R T I C L E I N F O
A B S T R A C T
Article history: Received 22 December 2010 Received in revised form 28 March 2011 Accepted 29 March 2011 Available online 11 June 2011
Cognitive biases may not be seen in all subtypes of delusions, and might be more involved in the etiology of some delusional subtypes than others. A sample of patients with delusions of reference did not show the jumping to conclusions (JTC) bias. JTC appears to be more closely related to paranoia than referential delusions. ß 2011 Elsevier Masson SAS. All rights reserved.
Keywords: Delusions of reference Probabilistic reasoning Attributional bias Theory of mind Paranoia ‘Jumping to conclusions’
1. Introduction
2. Methods
A number of cognitive biases have been proposed as being related to delusions in schizophrenia. The underlying biases were initially postulated to be related to specific delusional processes, particularly paranoia [3,5,16,20,21]; however, most studies have typically considered groups of patients with delusions as a unitary group, and have not typically examined relationships between delusional subtypes. Cognitive biases might be associated only with some types of delusions, rather than delusions in general [14], or more generally associated with psychopathology [13,22,29]. Startup et al. [10] recently found the presence of a jumping to conclusions (JTC) response pattern in patients with paranoia, but indicated that patients who also showed delusions of reference did not show this cognitive bias to the same extent. This suggests that cognitive biases are involved to different degrees in the etiology of different subtypes of delusions. In the present study, we further explored this intriguing hypothesis by examining probabilistic reasoning, attributional style, and theory of mind in a group of patients with prominent delusions of reference, compared to a group of healthy controls.
2.1. Participants Eighteen patients with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder (verified using the MINI [19]), were recruited from the outpatient services of the Schizophrenia Program at the Centre for Addiction and Mental Health (CAMH), Toronto. Patients were invited to participate by their treating psychiatrists, who were informed about the study, and referred the patient if they had prominent delusions of reference. Symptom severity was assessed using the Scales for Assessment of Positive Symptoms (SAPS) [1]. Premorbid IQ was estimated using the reading subtest of the Wide Range Achievement Test-3 (WRAT-3) [33]. All patients had prominent delusions of reference (a score of at least 3 on the SAPS referential delusions item, indicating moderate severity, and referential ideation occurring at least weekly). All symptom ratings were carried out by the first author, using criteria developed by Startup et al. [14]. A group of 17 controls, with no history of psychiatric illness (also verified using the MINI) were recruited via flyers. All subjects gave written informed consent. 2.2. Tasks
* Corresponding author. Tel.: +1 416 535 8501; fax: +1 416 979 4656. E-mail address: [email protected] (M. Menon). 0924-9338/$ – see front matter ß 2011 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.eurpsy.2011.03.005
2.2.1. Probabilistic reasoning tasks Two versions of the probabilistic reasoning task were used, both adapted from earlier studies by our group [22,23]. In the neutral version of the task, participants are shown two jars containing
M. Menon et al. / European Psychiatry 28 (2013) 71–73
72
white and blue beads in opposing ratios of 60:40. Beads are presented one at a time, in a pseudo-random order, and then put back into the jar, until participants make a decision as to whether the beads were being drawn from the ‘mostly white’ or ‘mostly blue’ jar. The instructions used were identical to Exp 1 from Menon et al. [8]. For the ‘social’ variant of the task (sometimes referred to in the literature as the ‘emotionally salient version’ of the task) [6,22], participants were told to imagine that two surveys had been carried out about a person. On the ‘mostly good’ survey, 60 people made positive comments about the person whereas 40 people made negative comments, while the ‘mostly bad’ survey had the opposite ratio. Positive and negative adjectives were presented one at a time (at the rate of one word every 3 s) until the participants decided whether the results derived from the ‘mostly good’ or ‘mostly bad’ survey. Two or fewer draws-to-decision indicated a JTC response pattern [12,30]. 2.2.2. Theory of mind (ToM) task ToM was assessed with the Hinting task [5], which comprises 10 short passages presenting an interaction between two characters, ending with one of the characters dropping an obvious hint. The subject is then asked what the character really meant when he/she said this. If the subjects failed to give the correct response, they are given an even more obvious hint. A correct response is scored as 2 or 1 depending on when the response was given. 2.2.3. Attributional Reasoning task Attributional style was measured using the Internal, Personal and Situational Attributions Questionnaire (IPSAQ) [16]. Participants are presented with positive and negative scenarios, and asked to decide whether the cause was internal, personal, or situational. Based on their responses, two cognitive bias scores are computed. The externalizing bias (EB) is the number of internal attributions for positive events minus the number of internal attributions for negative events. Thus, a positive EB score indicates a self-serving bias. The personalizing bias (PB) indicates the proportion of external attributions for negative events which are attributed to personal, rather than situational, causes. A PB score greater than 0.5 indicates a greater tendency to use personal rather than situational attributions for negative events. Data were analyzed using SPSS 13 using repeated measures ANOVAs or between groups t-tests with the assumption of unequal variance to examine between group differences. 3. Results As can be seen from Table 1, there were no differences between groups on age, gender or estimated premorbid IQ. There were significant differences on years of education, but all reported Table 1 Demographic information and performance on cognitive tasks.
Gender (M/F) Age WRAT-3 standard score Years of education SAPS delusions total SAPS delusions of reference SAPS persecutory delusions Draws to decision (beads) Draws to decision (‘social’ version of the task) Hinting task Externalizing bias Personalizing bias *
P < .05;
**
P < .01
Patients
Controls
11/7 39.6 (12.4) 98.5 (14.1) 12.72 (2.5) 3.68 (0.9) 4.34 (0.9) 2.16 (1.6) 7.06 (2.2) 8.35 (2.7) 16.67 (3.6) 0.83 (3.9) 0.63 (0.37)
10/7 35.7 (6.8) 105. 5 (9.5) 16.5 (2.3)** – – – 7.88 (2.8) 7.53 (2.8) 19.18 (1.1)* 4.35 (3.3)** 0.68 (0.26)
results remained unchanged when analyses were repeated using years of education as a covariate. There were no differences between patients and controls on probabilistic reasoning measures. None of the patients showed the JTC response pattern, and showed a tendency towards more draws to decision than controls on the ‘social’ variant of the task. Comparing performance on the two versions of the task, we found no effect of emotional salience, group, or a group by emotional salience interaction. On the IPSAQ, we found no evidence of any PB and patients showed significantly less EB. They also showed significantly poorer performance on the hinting task. The only significant relationship between task performance and symptomatology was a negative correlation between draws to decision on the ‘social’ variant of the task and the SAPS persecutory delusions score (r = .50, P = .03). Correlations between task performances on the different tasks in the complete sample found a positive correlation between performance on the two versions of the probabilistic reasoning tasks (r = 0.43, P = .01), and a negative correlation between draws to decision on the ‘social’ variant of the probabilistic reasoning task and performance on the hinting task (r = .35, P = .04). These relationships were present even when we examined correlations in the patient group alone (probabilistic reasoning tasks r = 0.5, P < .05; ‘social’ variant and hinting task r = .59, P < .05). We also carried out a secondary exploratory analysis to examine the specificity of the bias by dividing our group into patients with only delusions of reference (n = 9) and those with mixed referential and persecutory delusions (n = 9). Independent samples t-tests revealed trend level differences (P = 0.07) with the referential delusions only group taking significantly longer to arrive at a decision than the mixed delusions group on the ‘social’ variant of the beads task (mean draws to decision: referential delusions only 9.63, mixed delusions 7.22). None of the other tasks showed significant differences between the two patient groups. 4. Discussion The current study examined the performance of individuals with delusions of reference on three tasks thought to be associated with delusions. On the two probabilistic reasoning measures, there were three findings of interest: (i) none of the participants in our sample showed the JTC response pattern, performing similarly to the control group; (ii) patients who had only referential delusions showed a trend towards more draws to decision than the mixed delusions group and control group on the ‘social’ variant of the task; and, (iii) we found a negative correlation between performance on the ‘social’ variant of the task and persecutory delusions. This finding is consistent with Startup et al. [10], who reported JTC in patients with persecutory delusions but reduced JTC in patients with delusions of reference. We also found a negative correlation between performance on the hinting task and draws to decision on the ‘social’ variant of the probabilistic reasoning task, suggesting that performance on the two tasks might be related to one another or to common cognitive processes [17]. The absence of EBs or PBs on the IPSAQ is contrary to speculation that a self-serving bias is associated with delusions [4], but consistent with findings that only a subgroup of patients with persecutory and grandiose delusions show this bias [14]. Future studies should explore these differences as well as the use of variants of the IPSAQ that allow for finer grained analysis of attribution style [27]. The lack of a clinical control group is one limitation of the current study. While this curtails interpretability of the finding of poor ToM in the patients, it does not affect other results relevant to this line of investigation, specifically the absence of JTC in our deluded patient
M. Menon et al. / European Psychiatry 28 (2013) 71–73
group and the specificity of this result to those individuals who showed only referential delusions. The small sample size is another limitation, but it is in keeping with other studies that have examined JTC [4,13,23,27]. The absence of JTC, commonly seen in similar studies [7,10–12,25,30,32], and the conservative performance of both groups in the current study may reflect differences in sample characteristics or methodological differences in task administration that have not been explored in detail [22,28]. Delusions of reference occur as discrete events where the person has the feeling that an external stimulus (e.g. something said on the TV) is specifically about them. It has been speculated that these discrete events of heightened salience to external events [31] might be the result of aberrant dopamine firing [15,24]. Unlike other delusional subtypes which are characterized by long standing beliefs, we speculate that delusions of reference are driven by the experience of heightened self referentiality. This is consistent with other research [18], which suggests that cognitive biases are associated with abnormal beliefs, but not abnormal experiences. Other delusional subtypes, such as persecutory delusions, may also involve heightened self-reference, as well as other cognitive factors including threat anticipation [8], need for closure [2,9] and the cognitive biases outlined above. 5. Conclusions The present findings indicate that the data gathering bias might be associated with some delusional subtypes (persecutory delusions) more than others (delusions of reference), although the co-occurrence of both types of delusions in many patients makes it difficult to disentangle their individual effects. Cognitive interventions such as CBT or metacognitive training [26] should take these into account in creating specific targeted interventions for particular delusional subtypes. Disclosure of interest The authors declare that they have no conflicts of interest concerning this article. Acknowledgements The authors would like to thank Prof. Shitij Kapur for his useful comments on earlier drafts of the manuscript. References [1] Andreasen NC. The Scale for the Assessment of Positive Symptoms (SAPS). Iowa City: University of Iowa; 1983. [2] Bentall RP, Swarbrick R. The best laid schemas of paranoid patients: autonomy, sociotropy and need for closure. Psychol Psychother Theory Res Pract 2003;76:163–71. [3] Bentall RP, Kaney S, Dewey ME. Paranoia and social reasoning - an attribution theory analysis. Br J Clin Psychol 1991;30:13–23. [4] Bentall RP, et al. Persecutory delusions: a review and theoretical integration. Clin Psychol Rev 2001;21(8):1143–92.
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[5] Corcoran R, Mercer G, Frith CD. Schizophrenia, symptomatology and social inference - investigating theory of mind in people with schizophrenia. Schizophr Res 1995;17(1):5–13. [6] Dudley REJ, et al. The effect of self-referent material on the reasoning of people with delusions. Br J Clin Psychol 1997;36:575–84. [7] Fine C, et al. Hopping, skipping or jumping to conclusions? Clarifying the role of the JTC bias in delusions. Cogn Neuropsychiatr 2007;12(1):46–77. [8] Freeman D. Suspicious minds: the psychology of persecutory delusions. Clin Psychol Rev 2007;27(4):425–57. [9] Freeman D, et al. Delusions and decision-making style: use of the need for closure scale. Behav Res Ther 2006;44(8):1147–58. [10] Garety PA, Freeman D. Cognitive approaches to delusions: a critical review of theories and evidence. Br J Clin Psychol 1999;38:113–54. [11] Garety PA, Hemsley DR, Wessely S. Reasoning in deluded schizophrenic and paranoid patients - biases in performance on a probabilistic inference task. J Nerv Ment Dis 1991;179(4):194–201. [12] Garety PA, et al. Reasoning, emotions, and delusional conviction in psychosis. J Abnorm Psychol 2005;114(3):373–84. [13] Humphreys L, Barrowclough C. Attributional style, defensive functioning and persecutory delusions: symptom-specific or general coping strategy? Br J Clin Psychol 2006;45:231–46. [14] Jolley S, et al. Attributional style in psychosis –the role of affect and belief type. Behav Res Ther 2006;44(11):1597–607. [15] Kapur S. Psychosis as a state of aberrant salience: a framework linking biology, phenomenology, and pharmacology in schizophrenia. Am J Psychiatr 2003;160(1):13–23. [16] Kinderman P, Bentall RP. A new measure of causal locus: the internal, personal and situational attributions questionnaire. Pers Indiv Diff 1996;20(2): 261–4. [17] Langdon R, Ward PB, Coltheart M. Reasoning anomalies associated with delusions in schizophrenia. Schizophr Bull 2010;36(2):321–30. [18] Lawrence E, Peters E. Reasoning in believers in the paranormal. J Nerv Ment Dis 2004;192(11):727–33. [19] Lecrubier Y, et al. The MINI International Neuropsychiatric Interview (M.I.N.I.). A short diagnostic structured interview: reliability and validity according to the CIDI. Eur Psychiatry 1997;12:224–31. [20] Lee DA, et al. Delusional discourse: an investigation comparing the spontaneous causal attributions of paranoid and non-paranoid individuals. Psychol Psychother Theory Res Pract 2004;77:525–40. [21] Lyon HM, Kaney S, Bentall RP. The defensive function of persecutory delusions evidence from attribution tasks. Br J Psychiatr 1994;164:637–46. [22] Menon M, et al. Probabilistic reasoning in schizophrenia: a comparison of deluded and non-deluded schizophrenics and an exploration of possible cognitive underpinnings. Cognit Neuropsychiatry 2006;11(6):521–36. [23] Menon M, Mizrahi R, Kapur S. ‘Jumping to conclusions’ and delusions in psychosis: relationship and response to treatment. Schizophr Res 2008;98(1–3):225–31. [24] Menon M, et al. Exploring the neural correlates of delusions of reference. An fMRI study. Schizophr Bull 2008;102:90–190. [25] Moritz S, Woodward TS. Jumping to conclusions in delusional and nondelusional schizophrenic patients. Br J Clin Psychol 2005;44:193–207. [26] Moritz S, Woodward TS, and Metacognition Study Group. Metacognitive Skill Training for Patients with Schizophrenia (MCT), 2nd Edition. Manual, Hamburg: VanHam Campus Verlag; 2007. [27] Randjbar S, et al. Attributional biases in paranoid schizophrenia: further evidence for a decreased sense of self-causation in paranoia. Psych Psychol Soc Integr Appr 2011;3(1):74–85. [28] Rossell S, O’Regan A. Jumping to conclusions in delusions: fact or fallacy? Schizophr Res 2008;102((1–3) Suppl. 2):127–1127. [29] Startup M, Startup S. On two kinds of delusion of reference. Psychiatry Res 2005;137(1–2):87–92. [30] Startup H, Freeman D, Garety PA. Jumping to conclusions and persecutory delusions. Eur Psychiatry 2008;23(6):457–9. [31] Startup M, Bucci S, Langdon R. Delusions of reference: a new theoretical model. Cogn Neuropsychiatr 2009;14(2):110–26. [32] Van Dael F, et al. Data gathering: biased in psychosis? Schizophr Bull 2006;32(2):341–51. [33] Wilkenson GS, Jastak J. Wide Range Achievement Test - (WRAT-3), 3rd ed., Wilmington, DE: Wide Range, Inc; 1993.
Short communication
Examining cognitive biases in patients with delusions of reference M. Menon a,*,b, J. Addington a,b,c, G. Remington a,b a b c
Schizophrenia Program & PET Centre, Centre for Addiction & Mental Health, 250 College St, Toronto M5T 1R8, Canada Department of Psychiatry, University of Toronto, Toronto, Canada Department of Psychiatry, University of Calgary, Calgary, Canada
A R T I C L E I N F O
A B S T R A C T
Article history: Received 22 December 2010 Received in revised form 28 March 2011 Accepted 29 March 2011 Available online 11 June 2011
Cognitive biases may not be seen in all subtypes of delusions, and might be more involved in the etiology of some delusional subtypes than others. A sample of patients with delusions of reference did not show the jumping to conclusions (JTC) bias. JTC appears to be more closely related to paranoia than referential delusions. ß 2011 Elsevier Masson SAS. All rights reserved.
Keywords: Delusions of reference Probabilistic reasoning Attributional bias Theory of mind Paranoia ‘Jumping to conclusions’
1. Introduction
2. Methods
A number of cognitive biases have been proposed as being related to delusions in schizophrenia. The underlying biases were initially postulated to be related to specific delusional processes, particularly paranoia [3,5,16,20,21]; however, most studies have typically considered groups of patients with delusions as a unitary group, and have not typically examined relationships between delusional subtypes. Cognitive biases might be associated only with some types of delusions, rather than delusions in general [14], or more generally associated with psychopathology [13,22,29]. Startup et al. [10] recently found the presence of a jumping to conclusions (JTC) response pattern in patients with paranoia, but indicated that patients who also showed delusions of reference did not show this cognitive bias to the same extent. This suggests that cognitive biases are involved to different degrees in the etiology of different subtypes of delusions. In the present study, we further explored this intriguing hypothesis by examining probabilistic reasoning, attributional style, and theory of mind in a group of patients with prominent delusions of reference, compared to a group of healthy controls.
2.1. Participants Eighteen patients with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder (verified using the MINI [19]), were recruited from the outpatient services of the Schizophrenia Program at the Centre for Addiction and Mental Health (CAMH), Toronto. Patients were invited to participate by their treating psychiatrists, who were informed about the study, and referred the patient if they had prominent delusions of reference. Symptom severity was assessed using the Scales for Assessment of Positive Symptoms (SAPS) [1]. Premorbid IQ was estimated using the reading subtest of the Wide Range Achievement Test-3 (WRAT-3) [33]. All patients had prominent delusions of reference (a score of at least 3 on the SAPS referential delusions item, indicating moderate severity, and referential ideation occurring at least weekly). All symptom ratings were carried out by the first author, using criteria developed by Startup et al. [14]. A group of 17 controls, with no history of psychiatric illness (also verified using the MINI) were recruited via flyers. All subjects gave written informed consent. 2.2. Tasks
* Corresponding author. Tel.: +1 416 535 8501; fax: +1 416 979 4656. E-mail address: [email protected] (M. Menon). 0924-9338/$ – see front matter ß 2011 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.eurpsy.2011.03.005
2.2.1. Probabilistic reasoning tasks Two versions of the probabilistic reasoning task were used, both adapted from earlier studies by our group [22,23]. In the neutral version of the task, participants are shown two jars containing
M. Menon et al. / European Psychiatry 28 (2013) 71–73
72
white and blue beads in opposing ratios of 60:40. Beads are presented one at a time, in a pseudo-random order, and then put back into the jar, until participants make a decision as to whether the beads were being drawn from the ‘mostly white’ or ‘mostly blue’ jar. The instructions used were identical to Exp 1 from Menon et al. [8]. For the ‘social’ variant of the task (sometimes referred to in the literature as the ‘emotionally salient version’ of the task) [6,22], participants were told to imagine that two surveys had been carried out about a person. On the ‘mostly good’ survey, 60 people made positive comments about the person whereas 40 people made negative comments, while the ‘mostly bad’ survey had the opposite ratio. Positive and negative adjectives were presented one at a time (at the rate of one word every 3 s) until the participants decided whether the results derived from the ‘mostly good’ or ‘mostly bad’ survey. Two or fewer draws-to-decision indicated a JTC response pattern [12,30]. 2.2.2. Theory of mind (ToM) task ToM was assessed with the Hinting task [5], which comprises 10 short passages presenting an interaction between two characters, ending with one of the characters dropping an obvious hint. The subject is then asked what the character really meant when he/she said this. If the subjects failed to give the correct response, they are given an even more obvious hint. A correct response is scored as 2 or 1 depending on when the response was given. 2.2.3. Attributional Reasoning task Attributional style was measured using the Internal, Personal and Situational Attributions Questionnaire (IPSAQ) [16]. Participants are presented with positive and negative scenarios, and asked to decide whether the cause was internal, personal, or situational. Based on their responses, two cognitive bias scores are computed. The externalizing bias (EB) is the number of internal attributions for positive events minus the number of internal attributions for negative events. Thus, a positive EB score indicates a self-serving bias. The personalizing bias (PB) indicates the proportion of external attributions for negative events which are attributed to personal, rather than situational, causes. A PB score greater than 0.5 indicates a greater tendency to use personal rather than situational attributions for negative events. Data were analyzed using SPSS 13 using repeated measures ANOVAs or between groups t-tests with the assumption of unequal variance to examine between group differences. 3. Results As can be seen from Table 1, there were no differences between groups on age, gender or estimated premorbid IQ. There were significant differences on years of education, but all reported Table 1 Demographic information and performance on cognitive tasks.
Gender (M/F) Age WRAT-3 standard score Years of education SAPS delusions total SAPS delusions of reference SAPS persecutory delusions Draws to decision (beads) Draws to decision (‘social’ version of the task) Hinting task Externalizing bias Personalizing bias *
P < .05;
**
P < .01
Patients
Controls
11/7 39.6 (12.4) 98.5 (14.1) 12.72 (2.5) 3.68 (0.9) 4.34 (0.9) 2.16 (1.6) 7.06 (2.2) 8.35 (2.7) 16.67 (3.6) 0.83 (3.9) 0.63 (0.37)
10/7 35.7 (6.8) 105. 5 (9.5) 16.5 (2.3)** – – – 7.88 (2.8) 7.53 (2.8) 19.18 (1.1)* 4.35 (3.3)** 0.68 (0.26)
results remained unchanged when analyses were repeated using years of education as a covariate. There were no differences between patients and controls on probabilistic reasoning measures. None of the patients showed the JTC response pattern, and showed a tendency towards more draws to decision than controls on the ‘social’ variant of the task. Comparing performance on the two versions of the task, we found no effect of emotional salience, group, or a group by emotional salience interaction. On the IPSAQ, we found no evidence of any PB and patients showed significantly less EB. They also showed significantly poorer performance on the hinting task. The only significant relationship between task performance and symptomatology was a negative correlation between draws to decision on the ‘social’ variant of the task and the SAPS persecutory delusions score (r = .50, P = .03). Correlations between task performances on the different tasks in the complete sample found a positive correlation between performance on the two versions of the probabilistic reasoning tasks (r = 0.43, P = .01), and a negative correlation between draws to decision on the ‘social’ variant of the probabilistic reasoning task and performance on the hinting task (r = .35, P = .04). These relationships were present even when we examined correlations in the patient group alone (probabilistic reasoning tasks r = 0.5, P < .05; ‘social’ variant and hinting task r = .59, P < .05). We also carried out a secondary exploratory analysis to examine the specificity of the bias by dividing our group into patients with only delusions of reference (n = 9) and those with mixed referential and persecutory delusions (n = 9). Independent samples t-tests revealed trend level differences (P = 0.07) with the referential delusions only group taking significantly longer to arrive at a decision than the mixed delusions group on the ‘social’ variant of the beads task (mean draws to decision: referential delusions only 9.63, mixed delusions 7.22). None of the other tasks showed significant differences between the two patient groups. 4. Discussion The current study examined the performance of individuals with delusions of reference on three tasks thought to be associated with delusions. On the two probabilistic reasoning measures, there were three findings of interest: (i) none of the participants in our sample showed the JTC response pattern, performing similarly to the control group; (ii) patients who had only referential delusions showed a trend towards more draws to decision than the mixed delusions group and control group on the ‘social’ variant of the task; and, (iii) we found a negative correlation between performance on the ‘social’ variant of the task and persecutory delusions. This finding is consistent with Startup et al. [10], who reported JTC in patients with persecutory delusions but reduced JTC in patients with delusions of reference. We also found a negative correlation between performance on the hinting task and draws to decision on the ‘social’ variant of the probabilistic reasoning task, suggesting that performance on the two tasks might be related to one another or to common cognitive processes [17]. The absence of EBs or PBs on the IPSAQ is contrary to speculation that a self-serving bias is associated with delusions [4], but consistent with findings that only a subgroup of patients with persecutory and grandiose delusions show this bias [14]. Future studies should explore these differences as well as the use of variants of the IPSAQ that allow for finer grained analysis of attribution style [27]. The lack of a clinical control group is one limitation of the current study. While this curtails interpretability of the finding of poor ToM in the patients, it does not affect other results relevant to this line of investigation, specifically the absence of JTC in our deluded patient
M. Menon et al. / European Psychiatry 28 (2013) 71–73
group and the specificity of this result to those individuals who showed only referential delusions. The small sample size is another limitation, but it is in keeping with other studies that have examined JTC [4,13,23,27]. The absence of JTC, commonly seen in similar studies [7,10–12,25,30,32], and the conservative performance of both groups in the current study may reflect differences in sample characteristics or methodological differences in task administration that have not been explored in detail [22,28]. Delusions of reference occur as discrete events where the person has the feeling that an external stimulus (e.g. something said on the TV) is specifically about them. It has been speculated that these discrete events of heightened salience to external events [31] might be the result of aberrant dopamine firing [15,24]. Unlike other delusional subtypes which are characterized by long standing beliefs, we speculate that delusions of reference are driven by the experience of heightened self referentiality. This is consistent with other research [18], which suggests that cognitive biases are associated with abnormal beliefs, but not abnormal experiences. Other delusional subtypes, such as persecutory delusions, may also involve heightened self-reference, as well as other cognitive factors including threat anticipation [8], need for closure [2,9] and the cognitive biases outlined above. 5. Conclusions The present findings indicate that the data gathering bias might be associated with some delusional subtypes (persecutory delusions) more than others (delusions of reference), although the co-occurrence of both types of delusions in many patients makes it difficult to disentangle their individual effects. Cognitive interventions such as CBT or metacognitive training [26] should take these into account in creating specific targeted interventions for particular delusional subtypes. Disclosure of interest The authors declare that they have no conflicts of interest concerning this article. Acknowledgements The authors would like to thank Prof. Shitij Kapur for his useful comments on earlier drafts of the manuscript. References [1] Andreasen NC. The Scale for the Assessment of Positive Symptoms (SAPS). Iowa City: University of Iowa; 1983. [2] Bentall RP, Swarbrick R. The best laid schemas of paranoid patients: autonomy, sociotropy and need for closure. Psychol Psychother Theory Res Pract 2003;76:163–71. [3] Bentall RP, Kaney S, Dewey ME. Paranoia and social reasoning - an attribution theory analysis. Br J Clin Psychol 1991;30:13–23. [4] Bentall RP, et al. Persecutory delusions: a review and theoretical integration. Clin Psychol Rev 2001;21(8):1143–92.
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[5] Corcoran R, Mercer G, Frith CD. Schizophrenia, symptomatology and social inference - investigating theory of mind in people with schizophrenia. Schizophr Res 1995;17(1):5–13. [6] Dudley REJ, et al. The effect of self-referent material on the reasoning of people with delusions. Br J Clin Psychol 1997;36:575–84. [7] Fine C, et al. Hopping, skipping or jumping to conclusions? Clarifying the role of the JTC bias in delusions. Cogn Neuropsychiatr 2007;12(1):46–77. [8] Freeman D. Suspicious minds: the psychology of persecutory delusions. Clin Psychol Rev 2007;27(4):425–57. [9] Freeman D, et al. Delusions and decision-making style: use of the need for closure scale. Behav Res Ther 2006;44(8):1147–58. [10] Garety PA, Freeman D. Cognitive approaches to delusions: a critical review of theories and evidence. Br J Clin Psychol 1999;38:113–54. [11] Garety PA, Hemsley DR, Wessely S. Reasoning in deluded schizophrenic and paranoid patients - biases in performance on a probabilistic inference task. J Nerv Ment Dis 1991;179(4):194–201. [12] Garety PA, et al. Reasoning, emotions, and delusional conviction in psychosis. J Abnorm Psychol 2005;114(3):373–84. [13] Humphreys L, Barrowclough C. Attributional style, defensive functioning and persecutory delusions: symptom-specific or general coping strategy? Br J Clin Psychol 2006;45:231–46. [14] Jolley S, et al. Attributional style in psychosis –the role of affect and belief type. Behav Res Ther 2006;44(11):1597–607. [15] Kapur S. Psychosis as a state of aberrant salience: a framework linking biology, phenomenology, and pharmacology in schizophrenia. Am J Psychiatr 2003;160(1):13–23. [16] Kinderman P, Bentall RP. A new measure of causal locus: the internal, personal and situational attributions questionnaire. Pers Indiv Diff 1996;20(2): 261–4. [17] Langdon R, Ward PB, Coltheart M. Reasoning anomalies associated with delusions in schizophrenia. Schizophr Bull 2010;36(2):321–30. [18] Lawrence E, Peters E. Reasoning in believers in the paranormal. J Nerv Ment Dis 2004;192(11):727–33. [19] Lecrubier Y, et al. The MINI International Neuropsychiatric Interview (M.I.N.I.). A short diagnostic structured interview: reliability and validity according to the CIDI. Eur Psychiatry 1997;12:224–31. [20] Lee DA, et al. Delusional discourse: an investigation comparing the spontaneous causal attributions of paranoid and non-paranoid individuals. Psychol Psychother Theory Res Pract 2004;77:525–40. [21] Lyon HM, Kaney S, Bentall RP. The defensive function of persecutory delusions evidence from attribution tasks. Br J Psychiatr 1994;164:637–46. [22] Menon M, et al. Probabilistic reasoning in schizophrenia: a comparison of deluded and non-deluded schizophrenics and an exploration of possible cognitive underpinnings. Cognit Neuropsychiatry 2006;11(6):521–36. [23] Menon M, Mizrahi R, Kapur S. ‘Jumping to conclusions’ and delusions in psychosis: relationship and response to treatment. Schizophr Res 2008;98(1–3):225–31. [24] Menon M, et al. Exploring the neural correlates of delusions of reference. An fMRI study. Schizophr Bull 2008;102:90–190. [25] Moritz S, Woodward TS. Jumping to conclusions in delusional and nondelusional schizophrenic patients. Br J Clin Psychol 2005;44:193–207. [26] Moritz S, Woodward TS, and Metacognition Study Group. Metacognitive Skill Training for Patients with Schizophrenia (MCT), 2nd Edition. Manual, Hamburg: VanHam Campus Verlag; 2007. [27] Randjbar S, et al. Attributional biases in paranoid schizophrenia: further evidence for a decreased sense of self-causation in paranoia. Psych Psychol Soc Integr Appr 2011;3(1):74–85. [28] Rossell S, O’Regan A. Jumping to conclusions in delusions: fact or fallacy? Schizophr Res 2008;102((1–3) Suppl. 2):127–1127. [29] Startup M, Startup S. On two kinds of delusion of reference. Psychiatry Res 2005;137(1–2):87–92. [30] Startup H, Freeman D, Garety PA. Jumping to conclusions and persecutory delusions. Eur Psychiatry 2008;23(6):457–9. [31] Startup M, Bucci S, Langdon R. Delusions of reference: a new theoretical model. Cogn Neuropsychiatr 2009;14(2):110–26. [32] Van Dael F, et al. Data gathering: biased in psychosis? Schizophr Bull 2006;32(2):341–51. [33] Wilkenson GS, Jastak J. Wide Range Achievement Test - (WRAT-3), 3rd ed., Wilmington, DE: Wide Range, Inc; 1993.