Externalizing and personalizing biases in persecutory delusions

The relationship with poor insight and theory-of-mind

Robyn Langdon*, Tonia Corner, Jen McLaren, Philip B. Ward, Max Coltheart

*Corresponding author for this work

    Research output: Contribution to journalArticle

    74 Citations (Scopus)


    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 [Bentall et al., 2000. PDs: A review and theoretical integration. Clinical Psychology Review, 21, 1143-1192]. 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.

    Original languageEnglish
    Pages (from-to)699-713
    Number of pages15
    JournalBehaviour Research and Therapy
    Issue number5
    Publication statusPublished - May 2006

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