Source Monitoring in Hearing Impaired Individuals Experiencing Auditory Hallucinations

Abstract

Introduction: The process in which pieces of information are attributed to different sources is called source monitoring. A current hypothesis in schizophrenia is that deficits in source monitoring result in self-generated information being attributed to an external source (externalizing bias), resulting in auditory hallucinations. This hypothesis has not been investigated in other hallucinating populations, like hearing impaired individuals with hallucinations. In this study, a sample of hearing impaired individuals is studied to see if an externalizing bias can be found in Hallucinating Hearing impaired Individuals (HHI), compared to Non-hallucinating Hearing impaired Individuals (NHI). Methods: The Source Recognition Task (SRT) was used as a measure of source monitoring, where participants have to attribute information acquired earlier to either 'self', 'other' or 'new'. Then, the number of correct answers and the number of externalizing mistakes were compared between HHI and NHI. Then it was examined if severity of hallucinations can be associated with general source monitoring abilities and the externalizing bias. Results: No differences were found between HHI and NHI in correct answers or in externalizing mistakes. However, the severity of auditory hallucinations could partly predict the degree of the externalizing bias. Discussion: No differences between HHI and NHI could be found in general source monitoring or in externalizing bias. Even though a link was found between severity of hallucinations and the externalizing bias, this seems to suggest that the externalizing bias does not play a role in the origins of auditory hallucinations. This indicates different mechanisms underlie auditory hallucinations in schizophrenia and hearing impairment.