Previous research suggests that tendencies to misattribute one's own thoughts to an external source, as assessed by an immediate source-monitoring test, are associated with auditory verbal hallucinations (AVHs). However, recent research suggests that such tendencies are associated instead with symptoms of thought interference. The main aim of the present study was to examine whether such tendencies are differentially associated with different types of thought interference, with AVHs, or with both. It has also been suggested that external misattributions are especially likely to occur with emotionally salient material and if the individual's focus is on the self. These suggestions were also tested. The positive psychotic symptoms of 57 individuals with a diagnosis of schizophrenia were assessed and they then completed the Self-Focus Sentence Completion blank. Immediately after completing each sentence they were asked to indicate to what extent the sentence was their own. The number of sentences that were not rated as completely their own served as their externalisation score. Externalisation scores correlated significantly with the severity of three symptoms: voices commenting, delusions of being controlled, and thought insertion. In a logistic regression analysis, all three of these symptoms were significantly and independently related to externalisation. Externalisation was not associated with either a negative or a neutral self-focus. Thus tendencies to misattribute one's own thoughts to an external source are associated with AVHs and some, but not all, symptoms of thought interference. The importance for externalisation of self-focused attention and of the emotional salience of the elicited thoughts was not supported.
Behaviour Research and Therapy Vol. 46, Issue 10, p. 1176-1180