بینش شناختی و تمایل هذیان: یک تحقیق با استفاده از پرسشنامه بینش بک شناختی

The present study investigated the relationship between delusion proneness, as assessed using the Peters et al. Delusions Inventory [Peters, E.R., Joseph, S.A., Garety, P.A., 1999. The measurement of delusional ideation in the normal population: Introducing the PDI (Peters et al. Delusions Inventory). Schizophr. Bull. 25 553–576], and cognitive insight, as assessed using the Beck Cognitive Insight Scale (BCIS; [Beck, A.T., Baruch, E., Balter, J.M., Steer, R.A., Warman, D.M., 2004. A new instrument for measuring insight: The Beck Cognitive Insight Scale. Schizophr. Res. 68, 319–329]. Two hundred undergraduate students with no history of psychotic disorder participated. Results indicated that, consistent with hypotheses, those higher in delusion proneness endorsed more certainty in their beliefs and judgment than those who were lower in delusion proneness (Self-Certainty subscale of the BCIS; p = .007). Contrary to hypotheses, however, those who were higher in delusion proneness were more open to external feedback and were more willing to acknowledge fallibility than those who were lower in delusion proneness (Self-Reflectiveness subscale of the BCIS; p = .002). The results are discussed in relation to theories of delusion formation.

Considerable research demonstrates that those who have delusions process information differently than those who do not have delusions. For example, those with delusions exhibit a jumping to conclusions reasoning bias; delusional individuals request less information before making a decision than do those without delusions (Dudley et al., 1997a, Dudley et al., 1997b and Huq et al., 1988). Further, despite their hasty decisions, those with delusions are overconfident in the decisions they make (Huq et al., 1988). Taken together, it seems that those with delusions make decisions in the absence of enough evidence and that they are more certain of their decisions than those who do not have delusions. The research on information processing differences between those with and without delusions has been used to develop theories related to the formation and maintenance of delusions. Garety and Freeman (1999) argue the possibility that the jumping to conclusions reasoning bias may play a role in the onset of delusions. They argue that such biases are likely present before the individual becomes delusional and that this bias is partly responsible for the acquisition of the delusion. While such theories of delusion formation are plausible, the majority of research has investigated those who already have delusions (e.g., Dudley et al., 1997a, Dudley et al., 1997b and Huq et al., 1988), making conclusions about delusion formation only speculative. One way of investigating theories related to delusion formation is to examine those who do not have active delusions, but who demonstrate some unusual beliefs. A measure, called the Peters et al. Delusions Inventory (PDI; Peters et al., 1999) was developed for use with the general population to determine who may be “delusion-prone.” While those who score high on delusion-proneness are considered to have schizotypal traits and may demonstrate some of the features of those with delusions, they do not have active delusions, which makes them a useful sample to investigate the thinking biases that might be present before delusion formation. Those in the general population who score high on measures of schizotypy have been shown to be at increased risk for developing psychosis ( Chapman et al., 1994 and Kwapil et al., 1997). Previous research using the PDI has demonstrated that those who are delusion prone process information differently than those who are not delusion prone. For example, research has demonstrated that those who are delusion prone jump to conclusions in a manner similar to those with delusions ( Colbert and Peters, 2002 and Linney et al., 1998). In addition, those who are delusion prone, relative to those who are not delusion prone, demonstrate response latencies when processing angry facial expressions, indicating a possible bias for such stimuli ( Green et al., 2001). A new self-report measure, the Beck Cognitive Insight Scale (BCIS), was developed to assess how those with psychosis self-reflect, as measured by their willingness to acknowledge fallibility and being open to external feedback, and to assess their self-certainty, as measured by their confidence in their decisions (Beck et al., 2004). The original examination of the BCIS tested individuals with and without psychotic disorders in an inpatient setting (Beck et al., 2004), and a follow up study investigated a group of middle age and older adults with schizophrenia in an outpatient setting (Pedrelli et al., 2004). A recent study investigated the BCIS in a normal population and found that the basic factor structure of the instrument was the same in a nonclinical sample (Warman et al., 2004). The BCIS has two factors, the first labeled Self-Reflectiveness, which assesses how much the individual believes he/she may be wrong at times and a willingness to admit such, and the second labeled Self-Certainty, which assesses how much the individual believes he/she is definitely correct about his/her decisions and experiences. Those who had psychotic disorders in the original study had significantly less cognitive insight than those without psychotic disorders (Beck et al., 2004); they were significantly less self-reflective and significantly more confident in their decisions relative to a psychiatric control group. While it is possible that such thinking styles are related to delusion formation and maintenance, without examination of a sample of those who are not delusional but who are, instead, delusion-prone, such a theory can only be speculative. The current study is an investigation into whether those who are delusion prone have impaired cognitive insight. Initial investigations have supported the notion that those who are delusion prone process information differently than those who are not delusion prone and that they demonstrate information processing that is similar to that of individuals with delusions (e.g., Green et al., 2001 and Linney et al., 1998). The BCIS taps dimensions that are similar to jumping to conclusions and overconfidence, both of which are related to delusions (Huq et al., 1988). Previous research has demonstrated that those with psychotic disorders have impaired self-reflectiveness and are overconfident relative to those without psychotic disorders (Beck et al., 2004). It is expected, then, that such results will also be found for those who are highly delusion prone relative to those who score low on a measure of delusion proneness.

To determine if demographic variables may have been related to scores on the Beck Cognitive Insight Scale, the effects of race, age, and sex were examined. There were no differences due to race on Self-Reflectiveness (F(5, 193) = .815; p = .54), Self-Certainty (F(5, 192) = .259; p = .935), or the Composite Index (F(5, 192) = .822; p = .536). There were no significant relationships due to age on Self-Reflectiveness (r = .080; p = .260), Self-Certainty (r = − .008; p = .907), or the Composite Index (r = .065; p = .362). There were no significant differences due to sex on Self-Reflectiveness (t (198) = − .866, p = .388. Differences did emerge, however, on Self-Certainty, suggesting that males (M = 7.87, S.D. = 2.66) were significantly more self-confident than females (M = 6.36, S.D. = 2.64; t (197) = 3.355, p = .001). Because of this difference, males' Composite Index was significantly lower (M = 5.49, S.D. = 4.94) than females' (M = 7.47, S.D. = 4.38; t (197) = − 2.596, p = .010). Thus, for the following analyses, for Self-Certainty and for the Composite Index, sex was entered into the regression model first, to determine if delusion proneness added any predictive value, over and above sex.