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Verbal hallucinations in normals, V: perceived reality characteristics
PERSONALITY AND INDIVIDUAL DIFFERENCES
PERGAMON
Personality and Individual Differences 25 (1998) 209-221
Verbal hallucinations
in normals, V: perceived reality characteristics
Terry R. Barrett*, Marlys R. Caylor Murray State University, Murray, KY 42071, U.S.A.
Received 20 October 1997
Abstract The perceived reality characteristics of verbal hallucinations reported by 24 college students were examined and compared to those of 20 hallucinating schizophrenic patients. The reality characteristics examined were the seven proposed by Aggernaes [Aggernaes, A. (1972). The experienced reality of hallucinations and other psychological phenomena. Acta Psychiatrica Scandinavica, 48,220-2381. These characteristics were assessed for the first verbal hallucination ever experienced and for the most recent verbal hallucination. There was no differential pattern of positive reality characteristics between the two groups for the first verbal hallucination. However for the most recent verbal hallucination, schizophrenic patients were less likely than college students to report the positive reality characteristic of Publicness and more likely than college students to report the positive reality characteristic of Involuntarity. It was suggested that the verbal hallucinations reported by college students meet the requirements of the definition of hallucinations. Mechanisms potentially responsible for the production of hallucinations associated with normal consciousness were discussed and differences between psychotic and non-psychotic hallucinations were explored. 0 1998 Elsevier Science Ltd. All rights reserved. Kqv words; hallucinations: verbal hallucinations; auditory hallucinations; reality characteristics; reality discrimination; reality monitoring
1. Introduction Over the past 100 years, there have been occasional studies published suggesting that hallucinations are a normal process of consciousness for some proportion of the general population. In one of the earliest and most comprehensive of such studies, Sidgwick (1894) collected data from approximately 17,000 participants in 10 countries. If a person indicated he had experienced an
*Corresponding author. E-mail: [email protected]. 0191-8869/98$19.00 0 1998Elsevier Science Ltd. All rights reserved. PII:SO191-8869(98)00014-2
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hallucination on a questionnaire, an interview team was dispatched to rule out the possibility that the hallucination was related to sleep, drugs, physical or mental illness. Sidgwick reported that 9.9% of his participants had experienced an hallucination when in a state of normal consciousness. More recently, West (1948) questioned approximately 1500 persons and found that 14.3% reported having experienced an hallucination and McKellar (1968) found that 25% of 500 individuals from the general population admitted to at least one hallucination. In the past 15years, there have been several more detailed investigations of hallucinations reported by individuals in the general population, particularly verbal hallucinations. Posey and Losch (1983) spent several years collecting reports of verbal hallucination experiences from individuals in the general population. Using these reports, the authors constructed a questionnaire that contained examples of 14 different verbal hallucinations. Of the 375 college students who completed this questionnaire, 71% indicated having had one of these experiences at least once in their life. In addition, 39% indicated they had heard their own voice speaking their thoughts aloud and five percent reported a conversation with the hallucinated voice. These findings have been replicated and extended in several studies (Barrett and Etheridge, 1992, 1994; Barrett, 1993). For example, Barrett and Etheridge (1992) asked 586 college students to complete a revised version of the questionnaire used by Posey and Losch (1983). Subjects were asked to indicate if an experience had ever happened to them and then to estimate the frequency of occurrence of each of those experiences. Across all of the items, the average percent of individuals who reported an experience was virtually the same as that reported by Posey and Losch (1983). Table 1 shows the kinds of verbal hallucinations included in both the Posey and Losch (1983) study and the Barrett and Etheridge (1992) investigation, the percent of individuals in the Barrett and Etheridge study who endorsed each item, and the percent of individuals in that study who indicated the experience occurred at least once a month. As can be seen there is a relatively large minority of students who claim to have relatively frequent occurrences of verbal hallucinations. These reporting rates are considerably higher than those reported by Sidgwick (1894) and West (1948). In those earlier studies, individuals were asked only if they had ever had an hallucinatorylike experience, without providing any examples of such experiences. In the more recent studies, subjects have been given descriptions and asked, for each description, if anything like that had ever happened to them. It is likely that the difference in the way the subjects were questioned in the two sets of studies account for the difference in reporting rates. In fact, Bentall and Slade (1985a) and Young et al. (1986) indicated that college students in Great Britain reported rates of verbal hallucination-like experiences similar to those shown in Table 1. Although these authors used a different questionnaire, it did contain individual examples of hallucinations as probes. All of these investigators have come to the conclusion that hallucinations, and in particular verbal hallucinations, are a regular part of normal consciousness for a relatively large minority of individuals in the normal population. However, one might argue that these reports are not veridical accounts of hallucinations. Rather, it might be that these reports reflect individual sensitivity to demand characteristics in the experimental situation. The idea is that those who report have not actually experienced hallucinations, but rather are people who have a strong need to help or be seen in a positive light by the experimenter. This particular hypothesis has been thoroughly tested and rejected by Barrett and Etheridge (1992) and by Barrett (1993). A second possibility is that the reports are of real conscious experiences but the experiences do not contain all of the characteristics required for the experience to be classified as an hallucination.
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Table 1. Percent of 586 college students reporting each verbal hallucination experience and percent of those reporting the experience occurred at least once a month (Barrett and Etheridge, 1992) Verbal hallucination
experience
Percent reporting at least once in my life
at least once a month
32.8
10.2
38.4
11.3
31.2
26.6
12.6
4.3
6.1
2.3
11.3
6.2
6.3
4.1
1. Sometimes when I’m in the house all alone, I hear a voice call my name...it’s just 2.
3. 4.
5. 6.
7.
once...like “Sally”. Last summer I was in the backyard. Suddenly I heard my husband call my name from inside the house. He sounded like something was wrong and his voice was loud and clear. I ran in but nobody was in the house. He was out in the garage and hadn’t called at all. I sometimes hear my thoughts aloud. I actually hear them spoken outside my head when no one really said anything. Sometimes when I am driving in my car, I hear my own voice coming from the back seat. It sounds like it is little short statements...usually soothing...like, “It’ll be all right” or “Now, just calm down”. I drive a lot at night. Sometimes I hear sounds in the back seat like people talking...just a word here and there, but no one is there. Sometimes I can hear the voice of my friend talking to me, when she is not there. It isn’t that I’m imagining her voice, I can really hear it. It sounds so much like her voice that when it happens, I often talk back to it. Almost every morning while I am alone, I have a pleasant conversation with my dead grandmother. I talk to her and quite regularly hear her voice actually aloud.
This hypothesis stems from a careful consideration of the definition of an hallucination. Slade and Bentall (1988) have proposed that hallucinations be defined as: Any precept-like experience which (a) occurs in the absence of an appropriate stimulus, (b) has the full force or impact of the corresponding actual (real) perception, and (c) is not amenable to direct and voluntary control by the experiencer (p. 23). According to this definition, the experience should have all of the reality characteristics of a perceptual experience except an appropriate external stimulus. It might be that the experiences reported by individuals in the general population do not possess these reality characteristics. Rather than hallucinations, these experiences might more accurately be described as day dreams or vivid images. The current study was designed to determine if reports of verbal hallucinations by individuals in the general population do possess the reality characteristics necessary to classify them as instances of hallucinations. A reality characteristics questionnaire was developed based on the work reported by Aggernaes and his colleagues (Aggernaes, 1972a, 1972b, 1994; Aggernaes and Nyeborg, 1972; Aggernaes and Haugsted, 1976; Aggernaes et al., 1976). Aggernaes (1972a) described seven reality dichotomies. Each of these is defined so that one characteristic is generally associated with the conscious experience of a real event in the world (a perception) and the other
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characteristic is generally associated with a conscious experience that is not of a real event in the world (an idea). The first of these pairs is Sensation vs Ideation. When the conscious experience is believed to have arisen because of the operation of one or more sensory systems, that experience is judged to have the positive reality characteristic of Sensation. When the experience does not seem to come from the operation of a sensory system the experience is judged to have the negative reality characteristic Ideation. Aggernaes (1972a) suggested using questions like “Is this something you hear or is it something you think or imagine?” (p. 222) in making a decision concerning this reality dimension. Another dichotomy is Behavior Relevance vs No Behavior Relevance. He suggested that the answers to questions such as “Does what the voices tell you please you, or does it perhaps make you angry, afraid or sad?” (p. 223) allows an investigator to distinguish between the positive reality characteristic of Behavior Relevance and the negative reality characteristic of No Behavior Relevance. The third dichotomy is Publicness vs Privateness. The idea is that a conscious experience is said to have the positive reality characteristic of Publicness if the person having the experience believes, at the time the experience occurred, that anyone else with appropriate sensory systems could also have experienced the event. Questions like “Would I have been able to hear the voices, too, if I had been there and had been listening?” (p. 223) were suggested to get at the distinction between the positive reality characteristic of Publicness and the negative reality characteristic of Privateness. The fourth dichotomy is Objectivity vs Subjectivity. For a conscious experience to be judged to have the positive reality characteristic Objectivity, the person must believe that, at the time of the experience, some part of the origin of the event could have been experienced by at least one other sensory system. For example, if a person responded positively to the question “Are the emitters of the voices persons in flesh and blood which can eventually be found and seen or touched?” (p. 225), that experience would be judged to have the positive reality characteristic of Objectivity. The fifth pair of concepts is Existence vs Non-existence. According to Aggernaes (1972a), a conscious event is judged to have the positive reality characteristic of Existence if the person believes the event would have existed even if no one had actually experienced the event. Aggernaes suggested that a question such as “Does the emitter of the sound or voices also exist when nobody is there to experience these sounds or him ?” (p. 226) would allow one to make such a decision about this reality characteristic. The sixth dichotomy Aggernaes described is Independence vs Dependence. A conscious experience is judged to have the positive reality characteristic of Independence if the person does not believe the experience arose simply because she was in some particular state, such as being anxious or because she had ingested drugs. Questions that allow an investigator to make this distinction include “Did you feel you heard the voices only because something was wrong with your nerves? Did you feel that you saw (heard) this only because you had taken LSD?” (p. 227). Negative answers to questions like this would lead to the judgment that the experience in question had the positive reality characteristic of Independence. The final dichotomy identified is Involuntarity vs Voluntarity. If the person believes it is impossible to alter the experience by simply wishing it to change, the conscious experience is said to have the positive reality characteristic of Involuntarity. Aggernaes suggested that a question
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such as “Can you easily dismiss or alter your hearing of the voices or is it difficult or impossible to do this simply by desiring it ?” (p. 227) can serve as the basis for making the distinction between the positive reality characteristic of Involuntarity and negative reality characteristic of Voluntarity. Aggernaes (1972a) interviewed 41 hallucinating, chronic schizophrenics concerning the reality characteristics of their hallucinations. He found these patients could generally make judgments about each of the seven dichotomies. Of the 45 hallucinations studied, 39 of which were verbal in nature, only 4% of the time was it impossible to decide whether the hallucination had the positive or negative reality characteristic in question. He also found that these patients had a systematic pattern of positive and negative reality characteristics. The vast majority of hallucinations (from 83% to 98% of those that could be classified) were judged to have the positive reality characteristics of Sensation, Behavior Relevance, Objectivity, Existence, Independence, and Involuntarity. However, only 30% of the hallucinations were judged to have the positive reality characteristic of Publicness. In a separate study (Aggernaes et al., 1976) non-psychotic individuals were asked to rate perceptions of a real external event, of an image of something that existed and of an image of something that does not exist using the seven reality dichotomies. These three conditions led to quite different patterns of positive reality characteristics. When a person was rating the perception of a real external event all of the subjects, without dissent, rated those events as having all seven positive reality characteristics. When asked to rate the experience of imagining a real thing or voice, all the subjects rated the conscious experience as having the positive reality characteristics of Behavior Relevance, Publicness, Objectivity, Existence, and Independence and having the negative reality characteristics of Ideation (not sensation) and Voluntarity (not Involuntarity). When asked to rate the reality characteristics of imagining something that doesn’t exist, all of the subjects indicated the experiences had all negative reality characteristics, except for the positive reality characteristic of Independence. These results indicate that it is possible to differentiate among possible sources of a conscious experience based on examinations of the pattern of positive and negative reality characteristics associated with that experience. Consequently, in the present study 24 college students who reported frequent verbal hallucinations were asked detailed questions about those experiences in order to make systematic judgments about the seven reality dichotomies. The responses of these college students were compared to those of 20 hospitalised, chronic schizophrenics with a long history of verbal hallucinations. The schizophrenic patients were included in the present study for two reasons. First, we wanted to assess the comparability of our assessment technique to that of Aggernaes (1972a). To do that, we needed to determine if our technique would yield a pattern of reports from a group of hallucinating schizophrenic patients similar to that reported by Aggernaes. Second, with chronic schizophrenic patients who have a documented history of hallucinatory activity, there is generally little disagreement among professionals that these individuals do, in fact, experience frequent verbal hallucinations. This suggests that the pattern of reality characteristics reported to be associated with verbal hallucinations by individuals in this group can reasonably be taken to indicate the perceived reality characteristics of actual verbal hallucinatory activity. Consequently, similar patterns of reality characteristics reported to be associated to verbal hallucinations by college students and hallucinating schizophrenics would add considerable evidence
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to the hypothesis that the experiences reported by college students were, in fact, verbal hallucinations. 2. Method 2.1. Subjects 2.1.1. College students
A pool of approximately 250 volunteers from introductory psychology classes was assessed for the occurrence of verbal hallucinations using the Verbal Hallucination Questionnaire (Barrett and Etheridge, 1992). From this pool, 24 subjects were randomly selected with the restriction that they had verbal hallucination scores in the top 25% of the distribution of scores. Scores were calculated by adding together the frequency of occurrence ratings to the seven experiences shown in Table 1. On the average, these individuals indicated they had experienced 4.79 of the experiences in Table 1. These 15 female and nine male participants had a mean age of 19.42 years. Five of these participants could not remember when they started having verbal hallucinations. The remainder of these subjects indicated experiencing verbal hallucinations for two to 13 years (mean = 7.89 years). 2.1.2. Schizophrenic patients This group consisted of 20 patients confined to a large, public psychiatric hospital. Initially, 41 patients were selected by a hospital staff psychologist, from a list of in-patients provided by the admissions office, who could be approached for interview and who met the following criteria: (a) the person had been diagnosed as schizophrenic according to the DSM-IV (APA, 1994); (b) the person admitted to having had verbal hallucinations; (c) the person had shown continuous signs of schizophrenia for at least six months or less continuously for at least two years; (d) according to hospital records, the person had experienced verbal hallucinations within the last five years; (e) the person had no evidence of organic brain syndrome or disorders such as epilepsy or psychosis other than schizophrenia in their medical records. Of the 41 patients identified, 14 refused to talk about their verbal hallucinations; six patients denied hearing voices and one patient complained of being too tired to complete the interview. The 20 patients interviewed had a mean age of 42.90 years. There were 13 females and seven males. According to case records, 11 of the patients were diagnosed as schizophrenia, paranoid type, chronic (nine with exacerbation). Four of the patients were diagnosed with schizophrenia, not otherwise specified, chronic with exacerbation. Four additional patients had the diagnosis of schizophrenia, undifferentiated type, chronic and one was diagnosed with schizophrenia, residual type. The number of years 19 of these patients reported experiencing verbal hallucinations ranged from three to 39years (mean=23.70). One subject could not remember the age the first hallucination occurred. All of these participants were being treated with an anti-psychotic drug at the time of the interview. 2.2. Material 2.2.1. Verbal hallucination scale
The questionnaire from which this scale comes was originally developed by Posey and Losch (1983) and later revised by Barrett and Etheridge (1992). The version of the questionnaire we used
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for this study consists of 22 different hallucination experiences. Subjects are asked to rate each experience on a five point scale where 1 = never, 2 = very seldom, 3 = occasionally, 4 = often and 5 = very often. The Verbal Hallucination Scale consists of seven of these experiences, all describing a verbal hallucination experience. The items that make up this scale are shown in Table 1. 2.2.2. Reality characteristics As part of a long and detailed questionnaire concerning characteristics of hallucinations, questions suggested by Aggernaes (1972a) were included to assess the seven reality dichotomies of Sensation vs Ideation; Behavioral Relevance vs Non-behavioral Relevance; Publicness vs Privateness; Existence vs Non-existence; Independence vs Dependence; and Involuntarity vs Voluntarity. 2.3. Procedure All of the participants were interviewed individually and in one session. Each dichotomy was assessed twice, once for the first hallucination the person could remember and once for the most recently occurring hallucination. When the subject was unsure, the experimenter probed for information that might allow the participant to reach a clear decision. The interviews averaged about 90 min each.
3. Results To begin the interview, each individual was asked to describe his first and most recent verbal hallucination. This was done to be sure that the experience being evaluated was, in fact, a verbal experience. All of the subjects indicated that the experience was verbal in nature. Each subject was also asked, for the first verbal hallucination and for the most recent one, if the hallucination was like a dream. For the first hallucination, five (25%) schizophrenic patients and nine (39%) college students were unable to reject the possibility that the experience was like a dream. For the most recent hallucination, one (5%) schizophrenic patient and four (17%) college students were unable to exclude the possibility of the experience being like a dream. In order to assess for the possibility of psychopathology among the college student participants, each of the college students was asked to complete the MMPI (Hathaway and McKinley, 1967) in a separate session after completing the interview. The MMPI profiles were evaluated for possible psychopathology by two clinical psychologists on staff in the Psychology Department at the university. Based on these evaluations, 15 college students were identified, all of whom showed absolutely no indications of any psychopathology on the MMPI and were not in treatment for any emotional problem. Three series of Chi Square analyses were conducted. The first compared all 24 college students to all 20 schizophrenic patients on each of the reality dichotomies, separately for the first hallucination and for the most recent hallucination. The second compared only the college students and the schizophrenic patients for whom the experiences were clearly not dream like. The third compared only the 15 college students with absolutely no indication of psychopathology to the
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Table 2. Percent of college students and schizophrenic patients reporting each positive reality characteristic for the first and most recent verbal hallucination Positive reality characteristics
Sensation Beh. Relevance Publicness Objectivity Existence Independence Involuntarity
First hallucination
Most recent hallucination
college students
schizophrenic patients
college students
schizophrenic patients
percent
No.
percent
No.
percent
No.
percent
No.
83.33 100.00 8.82 73.68 55.56 84.21 73.68
15 16 10 14 10 16 14
92.86 100.00 46.15 50.00 50.00 93.75 86.67
13 15 6 5 6 15 13
95.45 83.33 63.64 70.83 62.50 79.17 58.33
21 15 14 17 15 19 14
94.14 100.00 23.53 42.86 41.18 78.95 95.00
18 19 4 6 7 15 19
schizophrenic patients. All three of these sets of analyses yielded the same patterns of results. Consequently, only the analyses including all the participants will be reported. It was slightly more difficult to categorize the experience as having either the positive or negative reality characteristic in question when talking to the schizophrenic patients than when interviewing the college students. On the average 32% of the schizophrenic patient responses and 25% of the college student responses could not be classified for the first hallucination. For the most recent hallucination, 11% of the schizophrenic patient responses and 6% of the college student responses could not be classified. The percentages for the most recent hallucination are reasonably similar to the results reported by Aggernaes for his schizophrenic patients (4%), all of whom were reporting a recent hallucination. Table 2 shows the percent (and number) of participants who indicated the positive reality characteristic for each of the seven reality dichotomies for the first and most recent hallucination. On each reality characteristic, the percentage is based on only those subjects for which an unambiguous decision could be made. Separate Chi Square analyses for each dichotomy indicated no significant differences between schizophrenic patients and the college students on any of the reality dichotomies for the first verbal hallucination, However, on the most recent verbal hallucination, two significant Chi Squares were obtained. These were on the reality dichotomies of Publicness vs Privateness (X2= 4.70, p < 0.03) and Involuntarity vs Voluntarity (X2= 5.99, p < 0.02). As you can see in Table 2, the most recent verbal hallucination reported by college students was considerably more likely to be experienced as having the positive reality characteristic of Publicness than the one experienced by the schizophrenic patients. On the other hand, for the reality dichotomy of Involuntarity vs Involuntarity, the reverse was true. Here the most recent verbal hallucination experienced by the schizophrenic patients was more likely to have the positive reality characteristic of Involuntarity than the one experienced by the college students.
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4. Discussion The major question of interest in this study was whether the verbal hallucinations reported by college students could reasonably be thought of as hallucinations. For both the first verbal hallucination and the most recent one, more than 50% of the college students reported the experience as having all of the positive reality characteristics associated with a perceptual experience precipitated by an external stimulus event (Aggernaes et al., 1976). This seems to be a relatively clear indication that the majority of experiences being reported by college students as verbal hallucinations meet the commonly accepted definition of an hallucination. This pattern of reality characteristics is not consistent with the view that these experiences can be classified as just thinking about an external event. That is, the data do not seem to support the idea that these students are simply misunderstanding the instructions and are reporting images instead of hallucinations. When rating an image of an external event, Aggernaes et al. (1976) found that non-psychotic individuals reported all positive reality characteristics except for the reality dichotomies of Sensation vs Ideation and Involuntarity vs Voluntarity. For those two, all the subjects always reported the negative reality characteristics of Ideation and Voluntarity. The college students in the present study did not produce that pattern. Almost all of the reports had the positive reality characteristic of Sensation (rather than Ideation) and a clear majority of reports had the positive reality characteristic of Involuntarity (rather than Voluntarity). It is not likely that this pattern of observed reality characteristics reported by the college students is somehow misleading because a flawed assessment technique was used in the current study. An examination of the pattern of reality characteristics reported by the schizophrenic patients is generally quite consistent to that reported by Aggernaes (1972a). The two positive reality characteristics for which there is a noticeable difference between his findings and the current findings are Objectivity and Existence. Aggernaes (1972a) reported rates for these two characteristics above 80%. Our technique, on the other hand, produced rates of between 40 and 50%. Consequently, our technique turned out to be somewhat more conservative than that of Aggernaes in assigning those two positive reality characteristics. A conservative assignment of positive reality characteristics, of course, works against the hypothesis that the high incidence of positive reality characteristics reported by college students is an overestimation due to the assessment technique used in the present study. The majority of these experiences seem to have the reality characteristics generally associated with the definition of an hallucination. In addition, the pattern of reality characteristics associated with the verbal hallucinations reported by college students has much in common with the pattern of reality characteristics associated with the verbal hallucinations reported by hallucinating schizophrenic patients. With respect to the first verbal hallucination ever experienced, schizophrenic patients and college students remember them as being virtually the same with respect to the reality characteristics examined. In some respects, the first hallucination experienced might be thought to be the best one for examining the similarity in patterns of positive reality characteristics reported by college students and schizophrenic patients. Based on the interview and an examination of their medical records, none of the schizophrenic individuals, at the time of the first hallucination, was being treated with any anti-psychotic medication. In fact, the majority of schizophrenic patients interviewed indicated that it was this hallucination that led to them eventually being diagnosed as schizophrenic.
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Consequently, one might think of this hallucinatory experience of the schizophrenic patients as the least contaminated by all of the experiences associated with being labeled schizophrenic, including extended confinement and the extensive use of various anti-psychotic medications. On the other hand, the validity of introspective reports decreases as the temporal interval between the report and the actual experience increases (Ericsson and Simon, 1993). Therefore, one might be more inclined to pay attention to the data gathered about the most recent hallucinatory experience. With respect to the reality dichotomies of Sensation vs Ideation, Behavior Relevance vs No Behavior Relevance, Objectivity vs Subjectivity, Existence vs Non-existence, and Independence vs Dependence, this data paints the same picture as that of the first hallucination. The schizophrenic patients and the college students did not differ in their descriptions of the positive reality characteristics associated with their verbal hallucinations. The two differences between schizophrenic patients and college students that did emerge were with respect to Publicness vs Privateness and Involuntarity vs Voluntarity. College students were considerably more likely than schizophrenic patients to report the hallucination as having the positive reality characteristic of Publicness. Consequently with respect to this particular reality dichotomy, the experiences reported by college students seem more consistent with the definition of hallucinations than those reported by the schizophrenic patients. The other significant difference between college students and schizophrenic patients was on Involuntarity vs Voluntarity for the most recent hallucination. Here college students were not as likely to report the positive reality characteristic (Involuntarity) as the schizophrenic patients. Thus, it appears that, at least some of the time, college students believe they have some measure of control over the experience. Exactly what sort of control they have, however, cannot be determined by the current data and, consequently, is a matter for additional research. However, even with respect to this reality dichotomy, college students reported the positive reality characteristic of Involuntarity more than 50% of the time. In summary, the experiences being rated by the college students in this study, by and large, seem to have the positive reality characteristics required for the experiences to be labeled hallucinations. It is certainly the case that with respect to positive reality characteristics, these hallucinations are as “hallucinatory” in nature as the experiences reported by schizophrenic patients. Furthermore, hallucinatory experiences with this pattern of reality characteristics are being reported by college students who showed no signs of psychopathology on the MMPI. This conclusion is consistent with an hypothesis proposed by Slade and Bentall (1988). They argued that hallucinations are not, necessarily, causally related to psychopathology. Rather, they suggested that hallucinations should be understood to be on a continuum of normal conscious experience that includes vivid thoughts and daydreams. The available evidence, although sparse, seems consistent with this view. Launay and Slade (198 l), Bentall and Slade (1985a), and Young et al. (1986) have presented evidence linking vivid thoughts, daydreams, and reports of hallucinatory experience in normal individuals. In addition, Barrett (1993) reported a positive relationship between the frequency of reported verbal hallucinations and rated vividness of imagery. The continuum hypothesis suggests that hallucinations reflect source discrimination errors. According to Slade and Bentall (1988) and Bentall (1990) hallucinations arise when an internally generated conscious experience (a thought) is mistakenly identified as an externally produced conscious experience (a perception). These authors refer to this process as reality discrimination. Bentall (1990) provides a particularly useful review of the research data consistent with this
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hypothesis. Further they suggest that it is analogous to the process Johnson and Raye (198 1) called reality monitoring in which subjects are asked to identify the original source of information in memory. One might expect to find the reality monitoring paradigm to be especially relevant as a method for investigating the mechanisms responsible for hallucinations. In particular, it seems reasonable to assume that variables related to reality monitoring errors might also be related to the occurrence of reality discrimination errors (i.e., hallucinations). Initial attempts to test this hypothesis have been reported by Bentall and Slade (1985b), Bentall et al. (199 l), and Rankin and O’Carroll(l995). Another important implication of the continuum hypothesis is that hallucinations associated with psychosis and those associated with normal conscious functioning are being produced by the same underlying mechanisms. In some sense, then, this perspective suggests that there will be fundamental similarities between these two types of hallucinations. Unfortunately, this issue has not, as yet, received any serious attention from researchers. The anecdotal evidence, however, does suggest some similarities. For example, hallucinations typically associated with schizophrenia are verbal in nature (e.g., Kaplan and Sadock, 1985). In fact, hearing one’s own voice (e.g., Schneider, 1959) and hearing a voice that talks to the person (World Health Organization, 1973) are both taken as important signs of psychosis. Yet both of these types of verbal hallucinations are reported with considerable frequency by college students we have assessed. Evidence reported in the present paper also suggests that the reality characteristics of hallucinations associated with psychosis and with normal consciousness are similar. Finally there is some agreement that psychotic hallucinations are experienced as having an external location (e.g., Goodwin et al., 1971). In like fashion, the hallucinations experienced during normal consciousness reported to us are perceived as having an external location. On the other hand, there also appear to be differences between the two types of experiences. It is often reported that psychotic hallucinations tend to have abusive content (e.g., Small et al., 1966) and that they generally occur, if not continuously, at great regularity with durations of up to an hour (Goodwin et al., 1971). Although we do not have systematic evidence about abusive content, it is our impression that verbal hallucinations associated with normal consciousness rarely, if ever, contain negative content. It also seems clear to us that there are substantial differences in the frequency and duration of hallucinations associated with psychosis and hallucinations associated with normal consciousness. The former seem to be much more frequent and have a much longer duration than the latter. Whether these similarities and differences warrant a claim of only quantitative differences or of a more basic qualitative difference will require much more careful empirical research than any yet reported in the scientific literature.
Acknowledgements The data reported here was collected as part of Marlys Caylor’s master’s thesis in Psychology at Murray State University. Thanks go to Dr J. Thomas Muehleman and Dr Judith Sheiman for reviewing the MMPI profiles of the college students for any indications of psychopathology. Preparation of this manuscript was supported, in part, by grant number 2-12869 and 2- 12704 to the first author from the Committee on Institutional Studies and Research, Murray State University.
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Barrett, T. R., & Etheridge, J. B. (1992). Verbal hallucinations
in normals, I: People who hear “voices”.
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Cognitive Psychology, 6, 379-387.
Barrett, T. R., & Etheridge, J. B. (1994). Verbal hallucinations
in normals, III: Dysfunctional
personality correlates.
Personality and Individual Differences, 16, 57-62.
Bentall, R. P. (1990). The illusion of reality: A review and integration
of psychological research on hallucinations.
Psychological Bulletin, 107, 82-95.
Bentall, R. P., & Slade, P. D. (1985a). Reliability of a scale measuring disposition towards hallucinations:
A brief report.
Personality and Individual Differences, 6, 527-529.
Bentall, R. P., & Slade, P. D. (1985b). Reality testing and auditory hallucinations:
A signal detection analysis.
British
Journal of Clinical Psychology, 24, 159- 169.
Bentall, R. P., Baker, G. A., & Havers, S. (1991). Reality monitoring and psychotic hallucinations.
British Journal of
Clinical Psychology, 30, 2 13-222.
Ericsson, K. A., & Simon, H. A. (1993). Protocol analysis: Verbal reports as data (Rev. ed.). Cambridge, MA: MIT Press. Goodwin, D. W., Alderson, P., & Rosenthal, R. (1971). Clinical significance of hallucinations in psychiatric disorders. Archives of General Psychiatry, 24, 7680.
Hathaway, S. R., & McKinley, J. C. (1967). Minnesota Multiphasic Personality Inventory: Manual (Revised 1967). New York: The Psychological Corp. Johnson, M. K., & Raye, C. L. (1981). Reality monitoring. Psychological Review, 88, 67-85. Kaplan, H. I., & Sadock, B. J. (1985). Modern synopsis of the comprehensive textbook of psychiatry/IV. Baltimore: Williams and Wilkins. Launay, G., & Slade, P. (1981). The measurement of hallucinatory predisposition in male and female prisoners. Personality and Individual Differences, 2, 22 l-234.
McKellar, P. (1968). Experience and behavior. Baltimore: Penguin Books. Posey, T. B., & Losch, M. E. (1983). Auditory hallucinations of hearing voices in 375 normal subjects.
Imagination,
Cognition and Personality, 3, 99-l 13.
Rankin, P. M., & O’Carroll, P. J. (1995). Reality discrimination, reality monitoring and disposition towards hallucination. British Journal of Clinical Psychology, 34, 5 17-528. Schneider, K. (1959). Clinical Psychopathology. (M. W. Hamilton, Trans.). New York: Grune and Stratton. (Original work published in 1959.). Sidgwick, H. (1894). Report of the census of hallucinations. Proceedings of the Society for Psychical Research, IO, 25422.
Slade, P. D. & Bentall, R. P. (1988). Sensory deception: A scientz$c analysis of hallucination. Baltimore: The Johns Hopkins Press.
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Small, 1. F., Small, J. G., & Anderson, J. M. (1966). Clinical characteristics of hallucinations of schizophrenia. Diseases of the Nervous System, 27, 299-309. West, D. J. (1948). A mass-observation questionnaire on hallucinations. Journal of the Society for Psychical Research, 34, 187-196.
World Health Organization (1973). Report of the International Pilot Study of Schizophrenia (Vol. 1). Geneva: Author. Young, H. F., Bentall, R. P., Slade, P. D., & Dewey, M. E. (1986). Disposition towards hallucination, gender and IQ scores. Personality and Individual Dlxferences. 7, 247-249.
PERGAMON
Personality and Individual Differences 25 (1998) 209-221
Verbal hallucinations
in normals, V: perceived reality characteristics
Terry R. Barrett*, Marlys R. Caylor Murray State University, Murray, KY 42071, U.S.A.
Received 20 October 1997
Abstract The perceived reality characteristics of verbal hallucinations reported by 24 college students were examined and compared to those of 20 hallucinating schizophrenic patients. The reality characteristics examined were the seven proposed by Aggernaes [Aggernaes, A. (1972). The experienced reality of hallucinations and other psychological phenomena. Acta Psychiatrica Scandinavica, 48,220-2381. These characteristics were assessed for the first verbal hallucination ever experienced and for the most recent verbal hallucination. There was no differential pattern of positive reality characteristics between the two groups for the first verbal hallucination. However for the most recent verbal hallucination, schizophrenic patients were less likely than college students to report the positive reality characteristic of Publicness and more likely than college students to report the positive reality characteristic of Involuntarity. It was suggested that the verbal hallucinations reported by college students meet the requirements of the definition of hallucinations. Mechanisms potentially responsible for the production of hallucinations associated with normal consciousness were discussed and differences between psychotic and non-psychotic hallucinations were explored. 0 1998 Elsevier Science Ltd. All rights reserved. Kqv words; hallucinations: verbal hallucinations; auditory hallucinations; reality characteristics; reality discrimination; reality monitoring
1. Introduction Over the past 100 years, there have been occasional studies published suggesting that hallucinations are a normal process of consciousness for some proportion of the general population. In one of the earliest and most comprehensive of such studies, Sidgwick (1894) collected data from approximately 17,000 participants in 10 countries. If a person indicated he had experienced an
*Corresponding author. E-mail: [email protected]. 0191-8869/98$19.00 0 1998Elsevier Science Ltd. All rights reserved. PII:SO191-8869(98)00014-2
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hallucination on a questionnaire, an interview team was dispatched to rule out the possibility that the hallucination was related to sleep, drugs, physical or mental illness. Sidgwick reported that 9.9% of his participants had experienced an hallucination when in a state of normal consciousness. More recently, West (1948) questioned approximately 1500 persons and found that 14.3% reported having experienced an hallucination and McKellar (1968) found that 25% of 500 individuals from the general population admitted to at least one hallucination. In the past 15years, there have been several more detailed investigations of hallucinations reported by individuals in the general population, particularly verbal hallucinations. Posey and Losch (1983) spent several years collecting reports of verbal hallucination experiences from individuals in the general population. Using these reports, the authors constructed a questionnaire that contained examples of 14 different verbal hallucinations. Of the 375 college students who completed this questionnaire, 71% indicated having had one of these experiences at least once in their life. In addition, 39% indicated they had heard their own voice speaking their thoughts aloud and five percent reported a conversation with the hallucinated voice. These findings have been replicated and extended in several studies (Barrett and Etheridge, 1992, 1994; Barrett, 1993). For example, Barrett and Etheridge (1992) asked 586 college students to complete a revised version of the questionnaire used by Posey and Losch (1983). Subjects were asked to indicate if an experience had ever happened to them and then to estimate the frequency of occurrence of each of those experiences. Across all of the items, the average percent of individuals who reported an experience was virtually the same as that reported by Posey and Losch (1983). Table 1 shows the kinds of verbal hallucinations included in both the Posey and Losch (1983) study and the Barrett and Etheridge (1992) investigation, the percent of individuals in the Barrett and Etheridge study who endorsed each item, and the percent of individuals in that study who indicated the experience occurred at least once a month. As can be seen there is a relatively large minority of students who claim to have relatively frequent occurrences of verbal hallucinations. These reporting rates are considerably higher than those reported by Sidgwick (1894) and West (1948). In those earlier studies, individuals were asked only if they had ever had an hallucinatorylike experience, without providing any examples of such experiences. In the more recent studies, subjects have been given descriptions and asked, for each description, if anything like that had ever happened to them. It is likely that the difference in the way the subjects were questioned in the two sets of studies account for the difference in reporting rates. In fact, Bentall and Slade (1985a) and Young et al. (1986) indicated that college students in Great Britain reported rates of verbal hallucination-like experiences similar to those shown in Table 1. Although these authors used a different questionnaire, it did contain individual examples of hallucinations as probes. All of these investigators have come to the conclusion that hallucinations, and in particular verbal hallucinations, are a regular part of normal consciousness for a relatively large minority of individuals in the normal population. However, one might argue that these reports are not veridical accounts of hallucinations. Rather, it might be that these reports reflect individual sensitivity to demand characteristics in the experimental situation. The idea is that those who report have not actually experienced hallucinations, but rather are people who have a strong need to help or be seen in a positive light by the experimenter. This particular hypothesis has been thoroughly tested and rejected by Barrett and Etheridge (1992) and by Barrett (1993). A second possibility is that the reports are of real conscious experiences but the experiences do not contain all of the characteristics required for the experience to be classified as an hallucination.
T. R. Barrett,
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Table 1. Percent of 586 college students reporting each verbal hallucination experience and percent of those reporting the experience occurred at least once a month (Barrett and Etheridge, 1992) Verbal hallucination
experience
Percent reporting at least once in my life
at least once a month
32.8
10.2
38.4
11.3
31.2
26.6
12.6
4.3
6.1
2.3
11.3
6.2
6.3
4.1
1. Sometimes when I’m in the house all alone, I hear a voice call my name...it’s just 2.
3. 4.
5. 6.
7.
once...like “Sally”. Last summer I was in the backyard. Suddenly I heard my husband call my name from inside the house. He sounded like something was wrong and his voice was loud and clear. I ran in but nobody was in the house. He was out in the garage and hadn’t called at all. I sometimes hear my thoughts aloud. I actually hear them spoken outside my head when no one really said anything. Sometimes when I am driving in my car, I hear my own voice coming from the back seat. It sounds like it is little short statements...usually soothing...like, “It’ll be all right” or “Now, just calm down”. I drive a lot at night. Sometimes I hear sounds in the back seat like people talking...just a word here and there, but no one is there. Sometimes I can hear the voice of my friend talking to me, when she is not there. It isn’t that I’m imagining her voice, I can really hear it. It sounds so much like her voice that when it happens, I often talk back to it. Almost every morning while I am alone, I have a pleasant conversation with my dead grandmother. I talk to her and quite regularly hear her voice actually aloud.
This hypothesis stems from a careful consideration of the definition of an hallucination. Slade and Bentall (1988) have proposed that hallucinations be defined as: Any precept-like experience which (a) occurs in the absence of an appropriate stimulus, (b) has the full force or impact of the corresponding actual (real) perception, and (c) is not amenable to direct and voluntary control by the experiencer (p. 23). According to this definition, the experience should have all of the reality characteristics of a perceptual experience except an appropriate external stimulus. It might be that the experiences reported by individuals in the general population do not possess these reality characteristics. Rather than hallucinations, these experiences might more accurately be described as day dreams or vivid images. The current study was designed to determine if reports of verbal hallucinations by individuals in the general population do possess the reality characteristics necessary to classify them as instances of hallucinations. A reality characteristics questionnaire was developed based on the work reported by Aggernaes and his colleagues (Aggernaes, 1972a, 1972b, 1994; Aggernaes and Nyeborg, 1972; Aggernaes and Haugsted, 1976; Aggernaes et al., 1976). Aggernaes (1972a) described seven reality dichotomies. Each of these is defined so that one characteristic is generally associated with the conscious experience of a real event in the world (a perception) and the other
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characteristic is generally associated with a conscious experience that is not of a real event in the world (an idea). The first of these pairs is Sensation vs Ideation. When the conscious experience is believed to have arisen because of the operation of one or more sensory systems, that experience is judged to have the positive reality characteristic of Sensation. When the experience does not seem to come from the operation of a sensory system the experience is judged to have the negative reality characteristic Ideation. Aggernaes (1972a) suggested using questions like “Is this something you hear or is it something you think or imagine?” (p. 222) in making a decision concerning this reality dimension. Another dichotomy is Behavior Relevance vs No Behavior Relevance. He suggested that the answers to questions such as “Does what the voices tell you please you, or does it perhaps make you angry, afraid or sad?” (p. 223) allows an investigator to distinguish between the positive reality characteristic of Behavior Relevance and the negative reality characteristic of No Behavior Relevance. The third dichotomy is Publicness vs Privateness. The idea is that a conscious experience is said to have the positive reality characteristic of Publicness if the person having the experience believes, at the time the experience occurred, that anyone else with appropriate sensory systems could also have experienced the event. Questions like “Would I have been able to hear the voices, too, if I had been there and had been listening?” (p. 223) were suggested to get at the distinction between the positive reality characteristic of Publicness and the negative reality characteristic of Privateness. The fourth dichotomy is Objectivity vs Subjectivity. For a conscious experience to be judged to have the positive reality characteristic Objectivity, the person must believe that, at the time of the experience, some part of the origin of the event could have been experienced by at least one other sensory system. For example, if a person responded positively to the question “Are the emitters of the voices persons in flesh and blood which can eventually be found and seen or touched?” (p. 225), that experience would be judged to have the positive reality characteristic of Objectivity. The fifth pair of concepts is Existence vs Non-existence. According to Aggernaes (1972a), a conscious event is judged to have the positive reality characteristic of Existence if the person believes the event would have existed even if no one had actually experienced the event. Aggernaes suggested that a question such as “Does the emitter of the sound or voices also exist when nobody is there to experience these sounds or him ?” (p. 226) would allow one to make such a decision about this reality characteristic. The sixth dichotomy Aggernaes described is Independence vs Dependence. A conscious experience is judged to have the positive reality characteristic of Independence if the person does not believe the experience arose simply because she was in some particular state, such as being anxious or because she had ingested drugs. Questions that allow an investigator to make this distinction include “Did you feel you heard the voices only because something was wrong with your nerves? Did you feel that you saw (heard) this only because you had taken LSD?” (p. 227). Negative answers to questions like this would lead to the judgment that the experience in question had the positive reality characteristic of Independence. The final dichotomy identified is Involuntarity vs Voluntarity. If the person believes it is impossible to alter the experience by simply wishing it to change, the conscious experience is said to have the positive reality characteristic of Involuntarity. Aggernaes suggested that a question
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213
such as “Can you easily dismiss or alter your hearing of the voices or is it difficult or impossible to do this simply by desiring it ?” (p. 227) can serve as the basis for making the distinction between the positive reality characteristic of Involuntarity and negative reality characteristic of Voluntarity. Aggernaes (1972a) interviewed 41 hallucinating, chronic schizophrenics concerning the reality characteristics of their hallucinations. He found these patients could generally make judgments about each of the seven dichotomies. Of the 45 hallucinations studied, 39 of which were verbal in nature, only 4% of the time was it impossible to decide whether the hallucination had the positive or negative reality characteristic in question. He also found that these patients had a systematic pattern of positive and negative reality characteristics. The vast majority of hallucinations (from 83% to 98% of those that could be classified) were judged to have the positive reality characteristics of Sensation, Behavior Relevance, Objectivity, Existence, Independence, and Involuntarity. However, only 30% of the hallucinations were judged to have the positive reality characteristic of Publicness. In a separate study (Aggernaes et al., 1976) non-psychotic individuals were asked to rate perceptions of a real external event, of an image of something that existed and of an image of something that does not exist using the seven reality dichotomies. These three conditions led to quite different patterns of positive reality characteristics. When a person was rating the perception of a real external event all of the subjects, without dissent, rated those events as having all seven positive reality characteristics. When asked to rate the experience of imagining a real thing or voice, all the subjects rated the conscious experience as having the positive reality characteristics of Behavior Relevance, Publicness, Objectivity, Existence, and Independence and having the negative reality characteristics of Ideation (not sensation) and Voluntarity (not Involuntarity). When asked to rate the reality characteristics of imagining something that doesn’t exist, all of the subjects indicated the experiences had all negative reality characteristics, except for the positive reality characteristic of Independence. These results indicate that it is possible to differentiate among possible sources of a conscious experience based on examinations of the pattern of positive and negative reality characteristics associated with that experience. Consequently, in the present study 24 college students who reported frequent verbal hallucinations were asked detailed questions about those experiences in order to make systematic judgments about the seven reality dichotomies. The responses of these college students were compared to those of 20 hospitalised, chronic schizophrenics with a long history of verbal hallucinations. The schizophrenic patients were included in the present study for two reasons. First, we wanted to assess the comparability of our assessment technique to that of Aggernaes (1972a). To do that, we needed to determine if our technique would yield a pattern of reports from a group of hallucinating schizophrenic patients similar to that reported by Aggernaes. Second, with chronic schizophrenic patients who have a documented history of hallucinatory activity, there is generally little disagreement among professionals that these individuals do, in fact, experience frequent verbal hallucinations. This suggests that the pattern of reality characteristics reported to be associated with verbal hallucinations by individuals in this group can reasonably be taken to indicate the perceived reality characteristics of actual verbal hallucinatory activity. Consequently, similar patterns of reality characteristics reported to be associated to verbal hallucinations by college students and hallucinating schizophrenics would add considerable evidence
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to the hypothesis that the experiences reported by college students were, in fact, verbal hallucinations. 2. Method 2.1. Subjects 2.1.1. College students
A pool of approximately 250 volunteers from introductory psychology classes was assessed for the occurrence of verbal hallucinations using the Verbal Hallucination Questionnaire (Barrett and Etheridge, 1992). From this pool, 24 subjects were randomly selected with the restriction that they had verbal hallucination scores in the top 25% of the distribution of scores. Scores were calculated by adding together the frequency of occurrence ratings to the seven experiences shown in Table 1. On the average, these individuals indicated they had experienced 4.79 of the experiences in Table 1. These 15 female and nine male participants had a mean age of 19.42 years. Five of these participants could not remember when they started having verbal hallucinations. The remainder of these subjects indicated experiencing verbal hallucinations for two to 13 years (mean = 7.89 years). 2.1.2. Schizophrenic patients This group consisted of 20 patients confined to a large, public psychiatric hospital. Initially, 41 patients were selected by a hospital staff psychologist, from a list of in-patients provided by the admissions office, who could be approached for interview and who met the following criteria: (a) the person had been diagnosed as schizophrenic according to the DSM-IV (APA, 1994); (b) the person admitted to having had verbal hallucinations; (c) the person had shown continuous signs of schizophrenia for at least six months or less continuously for at least two years; (d) according to hospital records, the person had experienced verbal hallucinations within the last five years; (e) the person had no evidence of organic brain syndrome or disorders such as epilepsy or psychosis other than schizophrenia in their medical records. Of the 41 patients identified, 14 refused to talk about their verbal hallucinations; six patients denied hearing voices and one patient complained of being too tired to complete the interview. The 20 patients interviewed had a mean age of 42.90 years. There were 13 females and seven males. According to case records, 11 of the patients were diagnosed as schizophrenia, paranoid type, chronic (nine with exacerbation). Four of the patients were diagnosed with schizophrenia, not otherwise specified, chronic with exacerbation. Four additional patients had the diagnosis of schizophrenia, undifferentiated type, chronic and one was diagnosed with schizophrenia, residual type. The number of years 19 of these patients reported experiencing verbal hallucinations ranged from three to 39years (mean=23.70). One subject could not remember the age the first hallucination occurred. All of these participants were being treated with an anti-psychotic drug at the time of the interview. 2.2. Material 2.2.1. Verbal hallucination scale
The questionnaire from which this scale comes was originally developed by Posey and Losch (1983) and later revised by Barrett and Etheridge (1992). The version of the questionnaire we used
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215
for this study consists of 22 different hallucination experiences. Subjects are asked to rate each experience on a five point scale where 1 = never, 2 = very seldom, 3 = occasionally, 4 = often and 5 = very often. The Verbal Hallucination Scale consists of seven of these experiences, all describing a verbal hallucination experience. The items that make up this scale are shown in Table 1. 2.2.2. Reality characteristics As part of a long and detailed questionnaire concerning characteristics of hallucinations, questions suggested by Aggernaes (1972a) were included to assess the seven reality dichotomies of Sensation vs Ideation; Behavioral Relevance vs Non-behavioral Relevance; Publicness vs Privateness; Existence vs Non-existence; Independence vs Dependence; and Involuntarity vs Voluntarity. 2.3. Procedure All of the participants were interviewed individually and in one session. Each dichotomy was assessed twice, once for the first hallucination the person could remember and once for the most recently occurring hallucination. When the subject was unsure, the experimenter probed for information that might allow the participant to reach a clear decision. The interviews averaged about 90 min each.
3. Results To begin the interview, each individual was asked to describe his first and most recent verbal hallucination. This was done to be sure that the experience being evaluated was, in fact, a verbal experience. All of the subjects indicated that the experience was verbal in nature. Each subject was also asked, for the first verbal hallucination and for the most recent one, if the hallucination was like a dream. For the first hallucination, five (25%) schizophrenic patients and nine (39%) college students were unable to reject the possibility that the experience was like a dream. For the most recent hallucination, one (5%) schizophrenic patient and four (17%) college students were unable to exclude the possibility of the experience being like a dream. In order to assess for the possibility of psychopathology among the college student participants, each of the college students was asked to complete the MMPI (Hathaway and McKinley, 1967) in a separate session after completing the interview. The MMPI profiles were evaluated for possible psychopathology by two clinical psychologists on staff in the Psychology Department at the university. Based on these evaluations, 15 college students were identified, all of whom showed absolutely no indications of any psychopathology on the MMPI and were not in treatment for any emotional problem. Three series of Chi Square analyses were conducted. The first compared all 24 college students to all 20 schizophrenic patients on each of the reality dichotomies, separately for the first hallucination and for the most recent hallucination. The second compared only the college students and the schizophrenic patients for whom the experiences were clearly not dream like. The third compared only the 15 college students with absolutely no indication of psychopathology to the
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Table 2. Percent of college students and schizophrenic patients reporting each positive reality characteristic for the first and most recent verbal hallucination Positive reality characteristics
Sensation Beh. Relevance Publicness Objectivity Existence Independence Involuntarity
First hallucination
Most recent hallucination
college students
schizophrenic patients
college students
schizophrenic patients
percent
No.
percent
No.
percent
No.
percent
No.
83.33 100.00 8.82 73.68 55.56 84.21 73.68
15 16 10 14 10 16 14
92.86 100.00 46.15 50.00 50.00 93.75 86.67
13 15 6 5 6 15 13
95.45 83.33 63.64 70.83 62.50 79.17 58.33
21 15 14 17 15 19 14
94.14 100.00 23.53 42.86 41.18 78.95 95.00
18 19 4 6 7 15 19
schizophrenic patients. All three of these sets of analyses yielded the same patterns of results. Consequently, only the analyses including all the participants will be reported. It was slightly more difficult to categorize the experience as having either the positive or negative reality characteristic in question when talking to the schizophrenic patients than when interviewing the college students. On the average 32% of the schizophrenic patient responses and 25% of the college student responses could not be classified for the first hallucination. For the most recent hallucination, 11% of the schizophrenic patient responses and 6% of the college student responses could not be classified. The percentages for the most recent hallucination are reasonably similar to the results reported by Aggernaes for his schizophrenic patients (4%), all of whom were reporting a recent hallucination. Table 2 shows the percent (and number) of participants who indicated the positive reality characteristic for each of the seven reality dichotomies for the first and most recent hallucination. On each reality characteristic, the percentage is based on only those subjects for which an unambiguous decision could be made. Separate Chi Square analyses for each dichotomy indicated no significant differences between schizophrenic patients and the college students on any of the reality dichotomies for the first verbal hallucination, However, on the most recent verbal hallucination, two significant Chi Squares were obtained. These were on the reality dichotomies of Publicness vs Privateness (X2= 4.70, p < 0.03) and Involuntarity vs Voluntarity (X2= 5.99, p < 0.02). As you can see in Table 2, the most recent verbal hallucination reported by college students was considerably more likely to be experienced as having the positive reality characteristic of Publicness than the one experienced by the schizophrenic patients. On the other hand, for the reality dichotomy of Involuntarity vs Involuntarity, the reverse was true. Here the most recent verbal hallucination experienced by the schizophrenic patients was more likely to have the positive reality characteristic of Involuntarity than the one experienced by the college students.
T. R. Barrett, M. R. CaylorlPersonality and Individual Differences 25 (1998) 209-221
4. Discussion The major question of interest in this study was whether the verbal hallucinations reported by college students could reasonably be thought of as hallucinations. For both the first verbal hallucination and the most recent one, more than 50% of the college students reported the experience as having all of the positive reality characteristics associated with a perceptual experience precipitated by an external stimulus event (Aggernaes et al., 1976). This seems to be a relatively clear indication that the majority of experiences being reported by college students as verbal hallucinations meet the commonly accepted definition of an hallucination. This pattern of reality characteristics is not consistent with the view that these experiences can be classified as just thinking about an external event. That is, the data do not seem to support the idea that these students are simply misunderstanding the instructions and are reporting images instead of hallucinations. When rating an image of an external event, Aggernaes et al. (1976) found that non-psychotic individuals reported all positive reality characteristics except for the reality dichotomies of Sensation vs Ideation and Involuntarity vs Voluntarity. For those two, all the subjects always reported the negative reality characteristics of Ideation and Voluntarity. The college students in the present study did not produce that pattern. Almost all of the reports had the positive reality characteristic of Sensation (rather than Ideation) and a clear majority of reports had the positive reality characteristic of Involuntarity (rather than Voluntarity). It is not likely that this pattern of observed reality characteristics reported by the college students is somehow misleading because a flawed assessment technique was used in the current study. An examination of the pattern of reality characteristics reported by the schizophrenic patients is generally quite consistent to that reported by Aggernaes (1972a). The two positive reality characteristics for which there is a noticeable difference between his findings and the current findings are Objectivity and Existence. Aggernaes (1972a) reported rates for these two characteristics above 80%. Our technique, on the other hand, produced rates of between 40 and 50%. Consequently, our technique turned out to be somewhat more conservative than that of Aggernaes in assigning those two positive reality characteristics. A conservative assignment of positive reality characteristics, of course, works against the hypothesis that the high incidence of positive reality characteristics reported by college students is an overestimation due to the assessment technique used in the present study. The majority of these experiences seem to have the reality characteristics generally associated with the definition of an hallucination. In addition, the pattern of reality characteristics associated with the verbal hallucinations reported by college students has much in common with the pattern of reality characteristics associated with the verbal hallucinations reported by hallucinating schizophrenic patients. With respect to the first verbal hallucination ever experienced, schizophrenic patients and college students remember them as being virtually the same with respect to the reality characteristics examined. In some respects, the first hallucination experienced might be thought to be the best one for examining the similarity in patterns of positive reality characteristics reported by college students and schizophrenic patients. Based on the interview and an examination of their medical records, none of the schizophrenic individuals, at the time of the first hallucination, was being treated with any anti-psychotic medication. In fact, the majority of schizophrenic patients interviewed indicated that it was this hallucination that led to them eventually being diagnosed as schizophrenic.
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Consequently, one might think of this hallucinatory experience of the schizophrenic patients as the least contaminated by all of the experiences associated with being labeled schizophrenic, including extended confinement and the extensive use of various anti-psychotic medications. On the other hand, the validity of introspective reports decreases as the temporal interval between the report and the actual experience increases (Ericsson and Simon, 1993). Therefore, one might be more inclined to pay attention to the data gathered about the most recent hallucinatory experience. With respect to the reality dichotomies of Sensation vs Ideation, Behavior Relevance vs No Behavior Relevance, Objectivity vs Subjectivity, Existence vs Non-existence, and Independence vs Dependence, this data paints the same picture as that of the first hallucination. The schizophrenic patients and the college students did not differ in their descriptions of the positive reality characteristics associated with their verbal hallucinations. The two differences between schizophrenic patients and college students that did emerge were with respect to Publicness vs Privateness and Involuntarity vs Voluntarity. College students were considerably more likely than schizophrenic patients to report the hallucination as having the positive reality characteristic of Publicness. Consequently with respect to this particular reality dichotomy, the experiences reported by college students seem more consistent with the definition of hallucinations than those reported by the schizophrenic patients. The other significant difference between college students and schizophrenic patients was on Involuntarity vs Voluntarity for the most recent hallucination. Here college students were not as likely to report the positive reality characteristic (Involuntarity) as the schizophrenic patients. Thus, it appears that, at least some of the time, college students believe they have some measure of control over the experience. Exactly what sort of control they have, however, cannot be determined by the current data and, consequently, is a matter for additional research. However, even with respect to this reality dichotomy, college students reported the positive reality characteristic of Involuntarity more than 50% of the time. In summary, the experiences being rated by the college students in this study, by and large, seem to have the positive reality characteristics required for the experiences to be labeled hallucinations. It is certainly the case that with respect to positive reality characteristics, these hallucinations are as “hallucinatory” in nature as the experiences reported by schizophrenic patients. Furthermore, hallucinatory experiences with this pattern of reality characteristics are being reported by college students who showed no signs of psychopathology on the MMPI. This conclusion is consistent with an hypothesis proposed by Slade and Bentall (1988). They argued that hallucinations are not, necessarily, causally related to psychopathology. Rather, they suggested that hallucinations should be understood to be on a continuum of normal conscious experience that includes vivid thoughts and daydreams. The available evidence, although sparse, seems consistent with this view. Launay and Slade (198 l), Bentall and Slade (1985a), and Young et al. (1986) have presented evidence linking vivid thoughts, daydreams, and reports of hallucinatory experience in normal individuals. In addition, Barrett (1993) reported a positive relationship between the frequency of reported verbal hallucinations and rated vividness of imagery. The continuum hypothesis suggests that hallucinations reflect source discrimination errors. According to Slade and Bentall (1988) and Bentall (1990) hallucinations arise when an internally generated conscious experience (a thought) is mistakenly identified as an externally produced conscious experience (a perception). These authors refer to this process as reality discrimination. Bentall (1990) provides a particularly useful review of the research data consistent with this
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hypothesis. Further they suggest that it is analogous to the process Johnson and Raye (198 1) called reality monitoring in which subjects are asked to identify the original source of information in memory. One might expect to find the reality monitoring paradigm to be especially relevant as a method for investigating the mechanisms responsible for hallucinations. In particular, it seems reasonable to assume that variables related to reality monitoring errors might also be related to the occurrence of reality discrimination errors (i.e., hallucinations). Initial attempts to test this hypothesis have been reported by Bentall and Slade (1985b), Bentall et al. (199 l), and Rankin and O’Carroll(l995). Another important implication of the continuum hypothesis is that hallucinations associated with psychosis and those associated with normal conscious functioning are being produced by the same underlying mechanisms. In some sense, then, this perspective suggests that there will be fundamental similarities between these two types of hallucinations. Unfortunately, this issue has not, as yet, received any serious attention from researchers. The anecdotal evidence, however, does suggest some similarities. For example, hallucinations typically associated with schizophrenia are verbal in nature (e.g., Kaplan and Sadock, 1985). In fact, hearing one’s own voice (e.g., Schneider, 1959) and hearing a voice that talks to the person (World Health Organization, 1973) are both taken as important signs of psychosis. Yet both of these types of verbal hallucinations are reported with considerable frequency by college students we have assessed. Evidence reported in the present paper also suggests that the reality characteristics of hallucinations associated with psychosis and with normal consciousness are similar. Finally there is some agreement that psychotic hallucinations are experienced as having an external location (e.g., Goodwin et al., 1971). In like fashion, the hallucinations experienced during normal consciousness reported to us are perceived as having an external location. On the other hand, there also appear to be differences between the two types of experiences. It is often reported that psychotic hallucinations tend to have abusive content (e.g., Small et al., 1966) and that they generally occur, if not continuously, at great regularity with durations of up to an hour (Goodwin et al., 1971). Although we do not have systematic evidence about abusive content, it is our impression that verbal hallucinations associated with normal consciousness rarely, if ever, contain negative content. It also seems clear to us that there are substantial differences in the frequency and duration of hallucinations associated with psychosis and hallucinations associated with normal consciousness. The former seem to be much more frequent and have a much longer duration than the latter. Whether these similarities and differences warrant a claim of only quantitative differences or of a more basic qualitative difference will require much more careful empirical research than any yet reported in the scientific literature.
Acknowledgements The data reported here was collected as part of Marlys Caylor’s master’s thesis in Psychology at Murray State University. Thanks go to Dr J. Thomas Muehleman and Dr Judith Sheiman for reviewing the MMPI profiles of the college students for any indications of psychopathology. Preparation of this manuscript was supported, in part, by grant number 2-12869 and 2- 12704 to the first author from the Committee on Institutional Studies and Research, Murray State University.
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