Poor intentional inhibition in individuals predisposed to hallucinations

Abstract

Introduction. Intentional inhibition deficits have been found in hallucinating individuals with schizophrenia using the Inhibition of Currently Irrelevant Memories (ICIM) task. This study sought to investigate whether similar difficulties are found in healthy individuals predisposed to hallucinations.

Methods. The Launay-Slade Hallucination Scale-Revised (LSHS-R) was completed by 589 undergraduate students, from which high- and low-predisposed groups were drawn. On the ICIM task, participants were asked to identify within-run picture repetitions, requiring them to inhibit memory traces of the same items seen in previous runs.

Results. Compared to the low LSHS-R group, the high LSHS-R group showed significantly increased false alarms on critical “inhibitory” runs (incorrectly identifying previous-run items as within-run repetitions), but no group differences were found in first-run false alarms or in the identification of within-run targets. These results were specific to hallucination predisposition and could not be explained by other schizophrenia-related characteristics.

Conclusions. Individuals predisposed to hallucinations show subtle, though consistent difficulties with intentional inhibition similar to patients with hallucinations. These findings demonstrate a continuity of cognitive processes in individuals predisposed to hallucinations and in patients with schizophrenia who hallucinate, consistent with a common neurodevelopmental pathway.

Acknowledgements

This work was supported by the Schizophrenia Research Institute, utilising funding from the Ron and Peggy Bell Foundation. We also thank Matt Huitson for his help with task programming.

Notes

¹The PDI was administered in the standard way, in which additional ratings are made for items responded to affirmatively. Data from these additional ratings are not reported.

²Two participants’ RT data were excluded due to errors in the RT recording program.