Subclinical delusional ideation and a self-reference bias in everyday reasoning.

Previous studies (e.g. Moller & Husby, 2000; Blackwood et al., 2004) have revealed that delusional thinking is accompanied by an exaggerated focus upon the self and upon stimuli that are perceived to be related to the self. The objective was to examine whether those high in subclinical delusional ideation exhibit a heightened tendency for self-reference. Using a mixed design, healthy individuals, classified into high- and low-scoring groups on the Peters et al. Delusions Inventory (Peters, Day, & Garety, 1996), were compared on everyday reasoning tasks across three experiments. High-PDI scorers, in contrast to the low-PDI group, rated self-referent objections to everyday arguments as stronger than other-referent objections and formulated more self-referent assertion-based objections to everyday arguments. The findings support the notion that subclinical delusional ideation is linked to a self-reference bias, which is evident in the sort of everyday thinking that people engage in when forming or evaluating their beliefs and which may contribute to delusion formation.