فرا شناخت در تمایل نسبت به توهم و هذیان ها

The objectives of the present study were to examine the degree of co-existence of hallucinations and delusions in the nonclinical population. In addition, we wished to investigate the role of metacognitions in hallucinations and delusions. Finally, we explored the relative roles of positive and negative metacognitive beliefs in proneness to hallucinations and delusions. Three hundred and thirty-one nonclinical participants completed instruments assessing: hallucination-proneness (Launay–Slade Hallucinations Scale; LSHS), delusion-proneness (21-item version of the Peters et al. Delusions Inventory; PDI-21) and metacognitive beliefs (Meta-Cognitions Questionnaire; MCQ). Participants were successively grouped according to their scores on the LSHS and the PDI-21. Results revealed that hallucination-proneness was positively and significantly associated with delusion-proneness. Furthermore, hallucination-prone and delusion-prone participants scored significantly higher on some sub-scales of the MCQ compared to non-prone participants. Finally, multiple regression analysis revealed that positive and negative beliefs were good predictors of proneness towards hallucinations and delusions.

A number of studies with psychotic patients have shown that positive psychotic symptoms (hallucinations and delusions) often co-exist (Bilder, Mukherjee, Rieder, & Pandurangi, 1985; Liddle, 1987; Peralta, de Leon, & Cuesta, 1992; Mortimer et al., 1996). However, studies have not adequately examined the degree of co-existence of these symptoms in nonclinical samples. For example, Verdoux et al. (1998a) found that, in addition to endorsing items on a measure of delusion-proneness, 16% of their nonclinical participants also reported that they had experienced hallucinations during their lifetime. The evaluation of hallucinations in Verdoux et al., 1998a, however, was only based on three single items (compared to 21 items that assessed delusion-proneness), which furthermore only assessed auditory hallucinations. More recently, Johns, Nazroo, Bebbington, and Kuipers (2002a) found an association between reports of hallucinations and other psychotic experiences based on the Psychosis Screening Questionnaire (Bebbington & Nayani, 1995); however, only two items concerning hallucinations were included in this study. Evidence of the co-existence of hallucinations and delusions suggests that these two symptoms may share common ground in terms of the psychological factors underlying their presence. Disturbances in the regulation of cognition have been put forward as factors modulating positive psychopathological symptoms (Bentall, 1990; Frith, 1992; Morrison, Haddock, & Tarrier, 1995; Garety, Kuipers, Fowler, Freeman, & Bebbington, 2001; Morrison, 2001). In particular, Morrison et al. (1995) suggest that hallucinations, in addition to other positive symptoms such as delusions, are likely to be associated with metacognitive beliefs. Metacognitive beliefs are beliefs that are linked to the interpretation, selection and execution of particular thought processes. This may include beliefs about thought processes (e.g. “I do not trust my memory”), the advantages and disadvantages of various types of thinking (e.g. “I need to worry, in order to work well”, “I could make myself sick with worrying”) and beliefs about the content of thoughts (e.g. “It is bad to think certain thoughts”) (Morrison, 2001). According to Morrison et al. (1995), metacognitive beliefs that are inconsistent with intrusive thoughts (e.g. “Not being able to control my thoughts is a sign of weakness”, “I cannot ignore my worrying thoughts”) lead to their external attribution as hallucinations. Furthermore, it is argued that such a misattribution is maintained because it reduces cognitive dissonance. When the occurrence of intrusive thoughts does not comply with the person's metacognitive beliefs, an aversive state of arousal results (cognitive dissonance), which the person tries to escape by externalising the intrusive thoughts (resulting in hallucinatory experiences), thus maintaining consistency in his/her belief system. For instance, based on Morrison et al.'s (1995) view, a person who believes that one should control all thoughts yet at the same time frequently experiences uncontrollable thoughts would tend to attribute these thoughts as stemming from something other than him or herself. Morrison et al. (1995) also claim that their account extends to include other positive symptoms, such as delusions. Intrusive thoughts may be defined as repetitive thoughts, images or impulses that are unacceptable or unwanted (Rachman, 1978). A number of studies have found similarities in both form and content between intrusive thoughts, on the one hand, and hallucinations and delusions, on the other hand. For instance, all three experiences are usually accompanied by subjective discomfort, are uncontrollable, and may be triggered by external precipitants such as stress and life-events. According to Morrison et al. (1995), these characteristics of intrusive thoughts highlight them as potentially useful in explaining positive symptoms, including hallucinations and delusions. More specifically, intrusive thoughts may be related to delusions, including thought insertion, thought withdrawal and thought broadcasting (as forms of uncontrollable or unwanted cognitive products) or delusions of control (as forms of intrusive impulses). Thus, since delusions can be considered as forms of intrusive thoughts, they may be amenable to the same mechanisms as hallucinations. A number of studies have found evidence for an association between metacognitive beliefs and the presence of hallucinations in both clinical and nonclinical samples (Baker & Morrison, 1998; Morrison, Wells, & Nothard, 2000; Morrison, Wells, & Nothard, 2002; Lobban, Haddock, Kinderman, & Wells, 2002; Morrison & Wells, 2003; Larøi, Collignon, & Van der Linden, in press; Larøi, Van der Linden, Marczewski, 2004a). For instance, Baker and Morrison (1998) found that schizophrenic patients with hallucinations scored higher (indicating a higher frequency of metacognitive beliefs) than non-hallucinating participants on a measure of metacognitive beliefs. In a group of hallucination-prone participants, Morrison et al. (2000) replicated the finding of an association between the presence of hallucinations and metacognitive beliefs. Studies have also reported an association between delusional ideation and metacognitions. For example, Freeman and Garety (1999) found that the majority of a sample of people with persecutory delusions experienced “meta-worry” (i.e. worry about worry) concerning the control of delusion-relevant thoughts. Finally, Morrison and Wells (2003) assessed metacognitive beliefs in psychotic patients with auditory hallucinations, psychotic patients with delusions, panic disorder patients, and nonpatient controls. The results showed that the psychotic patients with hallucinations tended to exhibit higher levels of dysfunctional metacognitive beliefs than the other patient groups and the nonpatient controls. It was also found that the metacognitive beliefs of patients with delusions and panic patients were elevated in comparison to nonpatients. Certain studies have specifically examined the relative roles of positive (e.g. “I need to worry in order to remain organised”) and negative (e.g. “My worrying is dangerous for me”) metacognitive beliefs in hallucinations (Morrison, Wells, & Nothard (2000) and Morrison, Wells, & Nothard (2002)). Morrison et al. (2000) performed multiple regression analysis with auditory and visual hallucination-proneness as dependent variables. Results revealed that positive beliefs about hallucinatory experiences were the best predictors of both auditory and visual hallucinations. Although Morrison et al. (2000) revealed an association between metacognitive beliefs and hallucination-proneness, the findings are not in accordance with Morrison et al.'s (1995) hypothesis that it is the presence of both positive and negative metacognitive beliefs that leads to cognitive dissonance, as in this study only positive beliefs were found to be significant predictors of hallucinations. Morrison et al. (2002) also included auditory and visual hallucination-proneness as dependent variables. In addition, metacognitive beliefs were assessed with the help of the Meta-Cognitions Questionnaire (MCQ; Cartwright–Hatton & Wells, 1997). Briefly, the MCQ assesses individual differences in positive and negative beliefs about worry and intrusive thoughts, metacognitive monitoring, and judgments of cognitive efficiency. Also based on regression analysis, Morrison et al. (2002) found that positive metacognitive beliefs were the best predictors of proneness towards auditory hallucinations. However, both negative and positive metacognitive beliefs were found to be significant predictors of proneness towards visual hallucinations. There are, however, certain methodological problems with the studies completed to date. In particular, these limitations concern both the assessment of visual and auditory hallucination-proneness, and the assessment of positive and negative beliefs about such experiences. Factor analysis of the version of the LSHS utilised in Morrison et al. (2000) revealed a two-factor solution representing (1) proneness towards visual hallucinations/disturbances and (2) proneness towards experiencing auditory or verbal hallucinations/daydreaming. However, many of the items included in the visual hallucinations-factor in Morrison et al. (2000) (e.g. “When I look at things they appear strange to me”, “When I look at things they look unreal to me”, “When I look at myself in the mirror I look different”) cannot be considered as visual hallucinations but, rather, as perceptual distortions/aberrations as there is no perception without object (i.e. the person reports perceiving an object that truly exists, albeit in a distorted form). Similarly, the auditory hallucinations factor contains items that normally saturate into a daydreaming factor or a vivid/intrusive thoughts factor (Levitan, Ward, Catts, & Hemsley, 1996; Aleman, Nieuwenstein, Böcker, & de Haan, 2001; Larøi, Marczewski, & Van der Linden, 2004b; Larøi & Van der Linden, 2005). The assessments of both auditory and visual hallucination-proneness in Morrison et al. (2002) also possess certain difficulties. Factor analysis of the revised form of the LSHS used in Morrison et al. (2002) resulted in a three-factor solution, consisting of factors assessing (1) vividness of imagination and daydreaming, (2) tendency towards experiencing visual disturbances and hallucinations, and (3) tendency towards experiencing auditory hallucinations. However, the items, “I hear a voice speaking my thoughts aloud,” and “I have had the experience of hearing a person's voice and then found that no one was there” were not included in the auditory hallucinations factor despite numerous studies reporting these items loading on an auditory hallucinations factor ( Levitan et al., 1996; Larøi et al., 2004b; Larøi & Van der Linden, 2005). Thus, the presence of visual and auditory hallucinations in Morrison et al. (2000), and the presence of auditory hallucinations in Morrison et al. (2002) may be viewed as being inadequately assessed, as they include experiences (daydreaming, intrusive and vivid thoughts, perceptual distortions) shown to be independent from visual and auditory hallucinations, while at the same time items normally loading on auditory and visual hallucination factors were not included in these respective factors. In addition, it is not entirely clear why only visual and auditory hallucination-proneness factors were included into regression analyses in Morrison et al. (2002) in light of the fact that a three-factor solution (vividness of imagination and daydreaming, tendency towards experiencing visual disturbances and hallucinations, tendency towards experiencing auditory hallucinations) was extracted after factor analysis in the same study. The inclusion of other hallucination factors in regression analysis may provide important information concerning the specificity of metacognitions in various types of hallucinatory experiences. Although studies have shown metacognitions to be important in typical hallucinations (e.g. auditory and visual hallucinations), no studies to date have examined the role of metacognitions in experiences related to hallucinations, such as vivid and intrusive thoughts, vivid daydreams, or sleep-related hallucinations. Metacognitive beliefs about intrusive thoughts were also insufficiently assessed in Morrison et al. (2000) and Morrison et al. (2002). In Morrison et al. (2000), positive metacognitive beliefs were only based on a single item (“Unusual experiences, such as those mentioned in the previous questionnaire, are beneficial and help me cope”), and negative beliefs were similarly only based on one item (“Unusual experiences, such as those mentioned in the previous questionnaire, are potentially dangerous and interfere with my life”). In contrast, in Morrison et al. (2002), positive and negative metacognitive beliefs were assessed with the help of the MCQ. Only three of the five MCQ sub-scales, however, were used as independent variables in their regression analyses (i.e. negative beliefs about the uncontrollability of thoughts and corresponding danger; negative beliefs about thoughts in general; positive beliefs about worry). The inclusion of only three sub-scales is particularly regrettable as other studies have shown that several of the MCQ sub-scales (not just the positive and negative metacognitive beliefs sub-scales) are significantly associated with the presence of hallucinations in clinical (Lobban et al., 2002; Morrison & Wells, 2003) and nonclinical (Morrison et al., 2000; Larøi et al., in press; Larøi et al., 2004a) persons. Furthermore, Morrison et al.'s (1995) cognitive model of hallucinations suggests that various metacognitive beliefs may play an important role in hallucinations (in addition to positive and negative metacognitive beliefs), such as cognitive self-consciousness and cognitive confidence. Taking into consideration the limits of previous studies and the existence of certain unexamined questions, the present study had the following goals. First, we examined the extent to which hallucination-proneness and delusion-proneness co-exist in nonclinical participants. Furthermore, we investigated associations between metacognitions, and hallucinations and delusions in a nonclinical sample. In addition, the relative influence of positive compared to negative metacognitive beliefs in proneness to delusions and hallucinations was elucidated. We hypothesised that proneness towards hallucinations and delusions would co-exist in the nonclinical participants. In terms of metacognitive beliefs, we assumed that both increased proneness towards hallucinations and increased proneness towards delusions would be associated with metacognitive beliefs. Finally, we hypothesised that both positive and negative metacognitive beliefs would be important predictors of hallucination-proneness and delusion-proneness. Method Participants Participants consisted of 331 nonclinical participants (University students). Participants were approached (in the context of their courses) for their co-operation, which was voluntary. No incentive was offered for participation. After discarding invalid protocols, 296 participants remained. Mean age was 23.1 years (SD=3.21). Of the participants, 192 were female and 104 were male.

The total LSHS score correlated significantly with the total PDI-21 score (r=0.48; p<0.0001). For subsequent correlations, we used Bonferroni corrections in order to diminish the probability of type-II errors due to the multiple correlations that were computed. Results revealed that the total PDI-21 score correlated significantly (all p<0.001) with the following LSHS factors: sleep-related hallucinations (r=0.29), auditory hallucinations (r=0.35), vivid thoughts (r=0.42) and visual hallucinations (r=0.37). Correlational analyses (with Bonferroni corrections) were also performed for the total LSHS score and the 7 PDI-factors identified in Verdoux et al. (1998b). This yielded significant correlations (all p<0.001) between the total LSHS score and the following PDI-21 factors: suspiciousness and persecutory ideas (r=0.29), thought disturbances and jealousy (r=0.32) and apocalyptic ideas (r=0.33).