No abstract

Abnormalities of 'social' reasoning were investigated in patients suffering from persecutory delusions and in matched depressed and normal controls using transparent (obvious) and opaque (unobvious) tests of attributional style. Whereas depressed and normal subjects yielded similar causal inferences for both attributional measures, the deluded subjects showed a marked shift in internality, attributing negative outcomes to external causes on the transparent Attributional Style Questionnaire but, on the more opaque Pragmatic Inference Task, attributing negative outcomes to internal causes and thus showing a cognitive style resembling that of the depressed group. This finding, interpreted in terms of explicit versus implicit judgements, supports the hypothesis that delusions function as a defence against underlying feelings of low self-esteem.

Attentional bias was investigated in patients suffering from persecutory delusions and matched psychiatric and normal controls, using the emotional Stroop task. Subjects were required to colour name words which were either meaningless strings of Os, neutral words, words indicating negative affect, or words judged to be of paranoid content. In comparison with the control subjects the deluded patients demonstrated a selective increase of response time for the paranoid words. A second analysis using indices of interference produced even more marked results. The relevance of these findings for the understanding of delusional thinking is discussed.

Seventeen psychotic patients with persecutory delusions were matched against depressed and normal controls and assessed for magical ideation, locus of control and attributional style. The deluded and depressed patients were found to make global and stable attributions when compared to the normal subjects. However, the deluded patients, in contrast with both control groups, made excessively external attributions for negative events and internal attributions for positive events. Highly significant differences were observed between the deluded group and the two control groups on magical ideation and on the 'powerful others' subscale of the locus of control questionnaire. Both psychiatric groups differed from the normal control group on 'chance' locus of control and a significant difference was observed between the persecuted and normal subjects on the 'internality' subscale of the questionnaire. The implications of these findings for the understanding and treatment of paranoid delusions are discussed.

SynopsisPatients suffering from persecutory delusions exhibit information processing and social reasoning biases that have been hypothesized to have a self-protective function. In a test of this hypothesis, patients suffering from persecutory delusions who were also depressed and non-depressed deluded subjects were compared with depressed and normal controls on two indirect assessments of self-schemata: the Dysfunctional Attitudes Scale (DAS) and incidental recall of negative and positive trait words that had previously been judged to be self-descriptive or not self-descriptive. Both the depressed subjects and the deluded subjects, whether or not they were depressed, scored highly on the DAS. Like normals, both depressed and non-depressed deluded subjects endorsed more positive than negative trait words as true of themselves whereas the depressed subjects endorsed as many negative as positive trait works. Like the depressed subjects, both groups of deluded subjects recalled as many of the negative words they had endorsed as positive words, whereas the normals remembered more positive words. No such bias was observed in subjects' recall of unendorsed words. The DAS results are interpreted as clearly consistent with a defensive model of persecutory delusions whereas the incidental recall data were equivocally so.