On the non-significance of internal versus external auditory hallucinations

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Abstract

Traditionally, auditory hallucinations (AHs) heard outside the head have been regarded as more pathological than those heard inside, partly on the basis that internal AHs are conceptually closer to normal thinking than external AHs. Our data show that many patients hear AHs both internally and externally, and there were very few associations between location and demographic and clinical characteristics of the patients or with other characteristics of the AHs themselves. There was evidence that AHs heard internally were associated with better insight than those heard externally. Of those patients whose AHs included commands, greater proportions of those who heard them externally said they could resist than those who heard them internally or in both locations. There appears to be no consistent differential impact and effect of internal and external AHs, and there was no support for the historical view that internal AHs are more benign.

Introduction

The differential significance of auditory hallucinations (AHs) heard inside or outside the head has a long and confusing history. The first treatment of the issue was by Jaspers (1962) who distinguished true hallucinations, heard in external space, from pseudohallucinations, which were located internally. He regarded the former as perceptions, in contrast to the latter, which were mental images. But, as Gelder et al. (1985, p. 6) point out, the term pseudohallucination has attracted two meanings, one based on location in internal, “subjective”, space, and the other based on the patient's recognition that the percept has “no correlate in the external world”, which might broadly be construed as insight. Most psychiatric texts have adopted the former meaning of pseudohallucination. Thus, Hamilton (1978, p. 35) says it “…lacks the vividness of a true percept and does not appear to be substantial and in perceptual space”. The same authority (Hamilton, 1974, p. 19) adds that pseudohallucinations are “…known not to be real perceptions and are not located in objective space but in subjective space”. Given that internal locus is a hallmark of the pseudohallucination, it is common to find true AHs described as arising externally. Sims (1995 p. 83) describes AHs as “…experienced as coming from outside [the] head or [the] self”. The AHs associated with depressive disorders are commonly thought to be located internally (Bloch and Singh, 2001 p. 165).

The pseudohallucination has been criticized for both conceptual confusion and lack of clinical utility (Berrios and Dening, 1996). Hamilton (1984) asserted that the pseudohallucination has no prognostic or diagnostic value in schizophrenia, and Trzepacz and Baker (1993, p. 108) observed that although “…some consider the former [voices originating within the head] to be relatively more healthy and/or insightful, this has not been established”. Despite this, Dening and Berrios (1996) found that 87% of a group of consultant psychiatrists believed in pseudohallucinations, and while most found it confusing, they were evenly split on its usefulness.

The characterization of the pseudohallucination, as experienced internally, implies that a “true” AH should be perceived externally. However, studies have found that AHs may occur in either or both locations. Junginger and Frame (1985) studied various aspects of the AHs of 52 hallucinating psychiatric patients and found that those that were heard externally were less clear than those heard internally. They concluded that historical notions that schizophrenics characteristically perceive external voices and that such voices are perceived as more real were not supported. Judkins and Slade (1981), studying a group of 26 patients with persistent AHs, found that for seven (27%), their voices were exclusively internal, for eight (31%), they were exclusively external, and the remaining eleven (42%) reported both kinds of voices. Nayani and David (1996) reported corresponding percentages of 38%, 49%, and 12%. Oulis et al. (1997) also studied 100 patients with psychosis and found that auditory hallucinations are mainly external, although in almost one third of the sample, internal hallucinations predominated.

Modern psychological approaches to the understanding and treatment of psychotic experiences tend to use cognitive and neuropsychological models in which such phenomena are explained in terms of attributions and/or dysfunction in regulatory processes Shergill et al., 1998, Blakemore et al., 2000, Garety et al., 2001. Thus, externally heard AHs may arise out of the misattribution of externality to “normal” perceptual intrusions and a breakdown in self-monitoring.

The unclear significance of the location of AHs indicates a continuing need to understand the differences between AHs heard internally and externally. We used a sample of 199 patients who responded to an exhaustive interview about their AHs (the Mental Health Research Institute Unusual Perceptions Schedule (MUPS) Carter et al., 1995) to explore these differences. On the basis of some of the literature reviewed, we were particularly interested to discover any associations between location and insight, affective variables, and the clarity of AHs.

Section snippets

Patients

One hundred and ninety-nine patients were interviewed; 134 (67.3%) were male and the mean age was 32.7 years (SD=10.67, range 15–63). Most (69.3%) had never been married, and most (84.9%) were born in an English-speaking country. Typically, educational attainment was secondary school level. About a third lived in their parental family home, another third lived in their own home, and the rest lived in boarding houses, private hotels, group homes, or sheltered accommodation. About 85% were

Location

Patients were asked where they heard their AHs. Of the 197 answering, 68 (34.5%) said inside the head, 55 (27.9%) said outside the head, and 74 (37.6%) said both. These results are presented in Table 1 alongside those of other studies for comparison.

The studies represented in Table 1 are remarkably consistent in the proportions of patients with AHs who report them as located inside the head, the percentages lying between 27% and 38%. The remainder are heard differently: two studies Junginger

Discussion

This study, with its much larger sample than previous similar studies, confirms that approximately one third of patients with AHs report them as located inside the head. The evidence is mixed as to how many report their AHs as occurring both internally and externally. We found that 38% of patients with AHs heard them both internally and externally, a similar rate to that of Judkins and Slade (1981). This relatively high prevalence limits the degree of interpretive significance that can be

Acknowledgements

We are indebted to the many patients who participated in this study. We also acknowledge the contribution of Dorothy Carter, Eliza Sims, and Rosemary Thomas who conducted most of the interviews. We are grateful to the National Health and Medical Research Council who contributed most of the funds for this project.

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