The Defensive Function of Persecutory Delusions

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.