title: Externalizing and personalizing biases in persecutory delusions: the relationship with poor insight and theory-of-mind.
abstract: The presence of externalizing bias (EB) for negative events together with personalizing bias (PB) (a bias to blame others rather than circumstances) may jointly constitute a vulnerability to develop persecutory delusions (PDs). Whereas EB purportedly serves to defend a vulnerable self-concept by avoiding negative self-attributions and might therefore exacerbate poor insight, PB may reflect cognitive deficits, including theory-of-mind impairment. We investigated these proposals in 34 schizophrenic patients with a history of PDs and 21 healthy controls. Patients with moderate- to severe-PDs and patients without a current PD showed excessive EB which was, surprisingly, absent in patients with mild persecutory delusions (mild-PDs). That EB might wax and wane with fluctuating delusional intensity was interpreted in accord with a new dynamic model of attribution self-representation cycles. As predicted, EB exacerbated poor insight. However, counter to predictions, theory-of-mind impairment did not increase PB, which was marked in all participants, whether clinical or non-clinical; instead, theory-of-mind impairment was also correlated with poor insight. Our findings indicate multiple pathways to poor insight, one of which is a theory-of-mind difficulty, impairing the capacity to simulate other perspectives for the purpose of critically evaluating one's own beliefs and circumstances.
authors.affiliation: Macquarie Centre for Cognitive Science, Macquarie University, Sydney, Australia. robyn@maccs.mq.edu.au
authors.forename: Robyn
authors.initials: R
authors.lastname: Langdon
authors.forename: Tonia
authors.initials: T
authors.lastname: Corner
authors.forename: Jen
authors.initials: J
authors.lastname: McLaren
authors.forename: Philip B
authors.initials: PB
authors.lastname: Ward
authors.forename: Max
authors.initials: M
authors.lastname: Coltheart
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003702:Delusions / Q000523:psychology*; D005260:Female; D006801:Humans; D007389:Internal-External Control; D008297:Male; D008875:Middle Aged; D010259:Paranoid Disorders / Q000523:psychology; D011582:Psychological Theory; D012565:Schizophrenic Psychology; D012649:Self Concept