Auditory verbal hallucination in schizophrenic patients and the general population: The sense of agency in speech

Recently, the boundaries between "normal" and "abnormal," even with regard to mental disorders, like schizophrenia even, have blurred. Thought auditory verbal hallucinations (AVH) are a cardinal feature of schizophrenia, recent studies have suggested that even healthy general population might experience the AVH (i.e., auditory verbal hallucination like experiences) (e.g., Barrett et al., 1992), indicating the continuum of schizophrenic symptoms. In this chapter, we reviewed the results of the studies about AVH both in schizophrenic patients, and the general population with AVH in terms of self-monitoring or sense of agency in speech, including our own studies. A perspective that situates schizophrenia on a continuum implies that this disorder constitutes a potential risk for everyone, and, thus,, helps toin promoteing understanding and correction ofing misunderstandings, whichthat contribute to prejudice within communities.We first reviewed the phenomenology of AVH in the general population including quality and quantity, as compared with patients with AVH. According to these previous studies, we developed the auditory hallucination experience scale (AHES) for general population because a scale for directly measuring AVH was needed. What causes AVH, even in the general population? Recent studies have suggested the relationship with to the sense of agency in speech.The sense of agency is the feeling of causing our own actions, in this case, speech (Gallagher, 2000). One's own speech could seem to be AVH (McGuigan, 1966). The activation of Broca's area, which can produce, but cannot listen to speech, has been associated with AVH (McGuire et al., 1993). ThereforeThus, these people might produce speech, but not think that they actually spoke. As a result, they may hear their own voices as the voices of others. Indeed, schizophrenic patients with AVH tend to misattribute their own speech (self-speech recognition task: e.g., Johns et al., 1999; 2001). To measure the subjective aspect of the sense of agency, we developed a scale to measure the sense of agency in a general population.The sense of agency approach to AVH could be a key not only to not only understanding schizophrenic cardinal symptom but also to understanding the sense of "self' in the healthy general population in the sense that, even the general population even could experience AVH. We Ffinally, we discussed on the neurocognitive model of the sense of agency in speech and its potential disturbance in people with AVH.