Dissociating the components of inhibitory control involved in predisposition to hallucinations

We have previously linked hallucinations in schizophrenia and hallucination predisposition to poor intentional inhibition. However, these previous studies have not systematically investigated the separable dimensions of inhibitory control involved, namely, intentional versus unintentional, and inhibition versus resistance to interference. The aim of this study was to clarify the critical component(s) of inhibitory control specifically related to hallucination predisposition.

The Launay-Slade Hallucination Scale-Revised (LSHS-R) was completed by 589 undergraduate students, from which high- (n=28) and low- (n=25) hallucination predisposition groups were drawn. Participants were administered tasks measuring unintentional inhibition (Brown-Peterson variant task) and intentional resistance to interference (directed ignoring [DI] task).

The high LSHS-R group showed significant difficulties relative to the low LSHS-R group on the DI task only; although these differences did not remain significant when controlling for anxiety or delusional thinking. Regression analyses showed that anxiety, but not delusional thinking, independently contributed to variance in DI task performance above that accounted for by hallucination predisposition.

Intentional rather than unintentional control of intrusive cognitions appears to play an important role in hallucination predisposition. The results indicate that difficulties with the intentional resistance to interference from concurrent external distractors may be a common mechanism underlying positive schizophrenia symptoms and anxiety. However, given previous findings reported by Paulik, Badcock, and Maybery (2007), we propose that hallucination predisposition is also characterised by a difficulty with the active suppression of intrusive cognitions - that is, intentional inhibition - which is not shared with anxiety or delusional symptoms.