Madness Explained

by Richard P. Bental

  Believing is seeing

  The findings of Romme and Escher in Holland, and Chadwick, Birchwood and Morrison in Britain, suggest that patients’ beliefs about their voices may influence how they are experienced, a conclusion that seems to be supported by the cross-cultural and historical studies that we examined at earlier in the book. American psychologist Ihsan Al-Issa has suggested that the positive attitude taken towards hallucinations in some developing countries reflects philosophical perspectives that differ markedly from the dominant philosophy of the Western world.31 In Western societies, where scientific materialism prevails, the need to distinguish between what is ‘real’ and what is ‘imaginary’ seems self-evident whereas, in less materialistic cultures, this distinction is less important.

  Al-Issa’s survey of the cross-cultural evidence revealed that visual hallucinations are more commonly reported by psychiatric patients in non-Western countries than by patients in the developed world, a finding that was supported by evidence from the WHO study of the Determinants of Outcome of Severe Mental Disorders.32 Similar differences have been observed in historical comparisons. Herman Lenz studied psychiatric records in Vienna that dated back over 100 years, finding that visual hallucinations were more often recorded at the end of the nineteenth century than in modern times.33 There is also evidence that the typical content of hallucinations has changed with the passing of centuries. Hallucinatory experiences recorded during the Middle Ages were almost always religious in content, whereas those reported by modern psychiatric patients often have persecutory or technological themes34 (one of my patients was convinced that the local police force was talking to him via a radio receiver that they had surgically implanted inside his head).

  The suspicion that these kinds of cross-cultural and historical differences reflect differences in people’s beliefs and expectations is fuelled by the results of studies in which hallucinations have been induced by suggestion. One of the first studies of this sort was carried out, not with psychiatric patients, but with students at a secretarial college. In the early 1960s, American social psychologists Theodore Barber and David Calverley attempted to demonstrate that most if not all hypnotic phenomena were caused by compliance with the hypnotist’s unusual instructions, rather than by the induction of a special trance state. In one of a series of experiments, they simply asked their group of secretarial students to close their eyes and listen to the record ‘White Christmas’, but did not actually play it. When questioned afterwards, about 5 per cent of the students said that they had heard the record.35

  When psychologists Sanford Mintz and Murray Alpert repeated this procedure with psychiatric patients in New York,36 they found that the ‘White Christmas’ effect was more pronounced inpatients who were experiencing hallucinations than in non-hallucinating patients or ordinary people, a finding that one of my postgraduate students, Heather Young, was later able to replicate.37

  The role of external stimulation

  The second factor that is known to influence hallucinations is external stimulation. Classical definitions of hallucination, for example Esquirol’s, imply that hallucinations occur in the absence of any stimulus. Of course this cannot be strictly true; there is always some kind of stimulus around. Patients’ accounts of their experiences often reveal the influence of this kind of background stimulation. For example, they may complain that their voices are worst when they are on their own at night, when they are in a crowd, or when they are close to electrical machinery such as fans and washing machines.

  In one of the few experiments to assess systematically the impact of stimulation on hallucinations, Andrew Margo, David Hemsley and Peter Slade asked a small group of highly co-operative patients to sit in a sound-proofed room and listen to various kinds of sounds. The experiment included a sensory-restriction condition, in which the participants wore headphones through which no sound was played, and other conditions in which participants heard interesting speech, boring speech, speech in a foreign language, pop music, meaningless blips and ‘white noise’ (the kind of unpatterned hiss that can be heard from a mistuned radio). The main finding was that the patients’ voices became worse (louder and longer in duration) during the sensory-restriction and white-noise conditions, but became less troublesome when the patients were listening to interesting speech. Margo and his colleagues also found that asking the patients to read aloud also seemed to suppress their hallucinations.38Figure 14.1 shows the results of an experiment that almost perfectly repeated these findings, which was recently carried out by Tony Gallagher and colleagues at Trinity College, Dublin.39

  Stress and the impact of emotion

  The third important factor that seems to affect hallucinations is emotional arousal. Clinical reports have documented cases of previously unaffected people who have experienced hallucinations following particularly stressful events, such as extended military operations,40 being trapped in a coal-mine,41 or after being taken hostage by terrorists. In the last case, a study by Ronald Siegel found that eight out of thirty-one terrorism victims experienced hallucinations varying from simple geometric shapes to complex memory images.42

  However, perhaps the best evidence of a link between emotional stress and hallucinations has emerged from investigations of people who have recently suffered bereavement. In one study carried out in Britain it was found that over 13 per cent of recently widowed men and women had heard their dead spouse’s voice.43 In another, carried out in Sweden, 71 per cent of bereaved elderly people reported a hallucination, or hallucinatory-like experience, of their deceased partner.44 The feeling that the deceased was present was particularly common. However, many of those surveyed reported seeing and talking to their dead spouse.45 These kinds of experiences were usually comforting, and were most commonly reported by people who described their marriages as very happy. It is possible that many apparent encounters with ghosts are in fact hallucinations of this sort.46

  Key to conditions 1: control (sitting quietly); 2: reading aloud; 3: listening to interesting speech; 4: listening to boring speech; 5: listening to pop music; 6: listening to regular electronic blips; 7: listening to irregular electronic blips; 8: sensory restriction (wearing headphones and dark goggles); 9: white noise. Figure 14.1 The effects of external stimulation on the duration, loudness and clarity of auditory hallucinations (from Gallagher, Dinin and Baker, 1994).

  As we have seen in earlier chapters, emotional arousal is usually accompanied by physiological phenomena, such as changes in the electrical conductivity of the skin (the electrodermal response). The relationship between these changes and hallucinations has hardly been investigated. However, one study has reported excessive fluctuations in skin conductance in hallucinating patients,47 and, in another, these fluctuations were observed to coincide with the appearance of voices.48

  Murmurings Within

  We are now close to being able to construct a theory of hallucinations. Before we proceed, however, it will be helpful to remind ourselves about a facet of normal mental life that seems particularly relevant to the experiences of patients who hear voices.

  In Chapter 8, I discussed the important phenomenon of inner speech, noting that we speak not only to other people but also to ourselves, and that silent speech directed to the self has important intellectual and emotional functions. We covertly comment to ourselves about what we have done, formulate our plans for the day ahead, keep transient memories (for example of telephone numbers) alive by rehearsing them, and wrestle with problems that we find emotionally challenging. However, despite the apparent silence of inner speech, it is accompanied by small activations of the speech muscles– a phenomenon known as subvocalization. These activations, which can be recorded using a machine called an electromyograph, occur because, in early childhood, we first learn to talk to ourselves out loud, and only later learn to suppress overt speech when no one else is listening. Subvocalization, therefore, is a neuromuscular echo of a time when we did not know how to speak silently.

  By now t
he reader will have realized why I took the trouble to discuss inner speech at length. As Ivan Leudar and Phil Thomas noted from their interviews with people who heard voices, the most common form of auditory hallucination – a voice or voices issuing instructions – mirrors the most common form of inner speech, which is a stream of instructions issued to the self.49 Other forms of auditory hallucination reflect less common forms of inner speech. For example, most people occasionally lapse into an inner debate or dialogue, in which different arguments or points of view are played off against each other. This form of inner speech is similar to the kind of auditory hallucination in which voices discuss the perceiver’s actions among themselves. The inescapable conclusion is that auditory hallucinations are inner speech.

  Hard evidence supporting this idea has been available since the late 1940s, when the first electromyographic studies of hallucinating patients were conducted at Norwich State Hospital in Connecticut by American psychiatrist Louis Gould.50 In his first experiment, using equipment that must be judged crude by modern standards, Gould conducted EMG assessments of 100 patients, finding raised muscular activity in the lips and chins of those who experienced voices. In a later study, he was able to show that the onset of this activity coincided with patients’ reports of hallucinations. This finding has since been repeated many times. Two Japanese psychiatrists, Tsuyoshi Inouye and Akira Shimizu, reported in 1970 that they had been able to time precisely the onset of increased activity in the speech muscles, and showed that this happened just a few seconds before their patients reported hearing voices. They also found that the duration and amplitude of the EMG activity they recorded corresponded with the duration and apparent loudness of their patients’ voices.51

  In two extraordinary case studies, researchers investigating the inner speech hypothesis even found that it was possible to record and listen to their patients’ voices. The first was conducted by Louis Gould, who used a sensitive microphone and amplifier to detect rapid subvocal speech in one of his patients.52 In a later study, British psychologists Paul Green and Martin Preston were able to record the whispers of a male patient who said that he was hearing the voice of a woman. When they amplified and played back their recordings to their patient this had the surprising (and as yet unexplained) effect of making his speech less and less silent, until both sides of the conversation between the patient and the voice could be clearly heard without the aid of special equipment.53

  Compelling though the electromyographical data are, they do not exhaust the physiological evidence in favour of the inner speech hypothesis. Hallucinations should be accompanied, not only by activation of the speech muscles, but also by activation of the centres in the brain that control language. Since the middle years of the nineteenth century, it has been known that, in the majority of people, these centres are located on the left side of the brain. An area of the left frontal cortex, identified by the French neurologist Paul Broca in the 1860s, appears to be particularly important in speech generation, so that damage to this area causes a form of expressive aphasia, in which the ability to transform verbal ideas into speech patterns is impaired. A second important area, located in the left temporal lobe, was discovered by the German neurologist and psychiatrist Karl Wernicke at approximately the same time. Damage to this area causes a disorder known as Wernicke’s aphasia, in which language comprehension is particularly disrupted.

  Figure 14.2 The left cerebral hemisphere of the brain, showing Broca’s and Wernicke’s areas (from N. Gershwind (1979) ‘Specializations of the human brain’, in The Brain: A Scientific American Book. San Francisco: Freeman).

  An attempt to measure brain activations in hallucinating patients by means of EEG, reported in 1982, found that the onset of auditory hallucinations coincided with an increase in activity in the left temporal lobe.54 This initial finding was later supplemented by evidence gathered by means of the new functional neuroimaging technologies, which allow activations in particular brain regions to be visualized with a precision that far exceeds that achievable with the best EEG equipment. Using single positron emission tomography (SPET) (a forerunner of PET) with a small group of co-operating patients, British psychiatrists Philip McGuire, G. M. Shah and Robin Murray were able to confirm that the onset of auditory hallucinations coincided with increased blood flow in the left temporal lobe, and also in Broca’s area.55

  A later study by David Silbersweig and colleagues, using PET, also found that auditory hallucinations were associated with activation of the left frontal cortex, together with structures deeper in the brain (various subcortical nuclei and paralimbic regions). They also studied a single drug-free patient who experienced combined auditory and visual hallucinations in which adisembodied head talked to him. These hallucinations were associated with activations not only in the auditory association cortex (near Wernicke’s area in the temporal lobe) but also in the visual association cortex towards the rear of the brain, which is involved in processing visual imagery.56

  Taken together, the EMG, EEG, SPET and PET findings strongly support the theory that auditory hallucinations consist of inner speech. The findings from the investigation by David Silbersweig and colleagues, which was unique in studying a patient with visual hallucinations, also imply that visual hallucinations consist of visual imagery. As Ralf Hoffman, a psychiatrist at Yale University, has pointed out, these discoveries therefore suggest that people who experience hallucinations are mistaking their own thoughts and imaginings for things they are hearing or seeing.57 Hoffman attempted to explain why these errors occur, by suggesting that a difficulty in planning speech might lead hallucinating patients to experience their speech as unintended and therefore alien to themselves. According to this idea, we mentally formulate a speech plan before we speak, and we recognize our speech as self-generated because it matches the plan. The hallucinating patient, who lacks a plan, is unable to do this.

  For some reason, this theory has attracted the attention of a number of professional philosophers, who have enjoyed pointing out various logical difficulties that it creates. Kathleen Akins and Daniel Dennett have objected that the idea that speech is normally preceded by a plan seems to create an infinite regress.58 If intelligent behaviour requires a plan, the plan itself (which is evidently intelligent) must surely also require a plan, and so we go on for ever. Of course, Hoffman might escape this objection by arguing that not all speech requires a plan, and that it is only unplanned speech that is mistaken for a voice. However, as G. Lynn Stephens and George Graham have observed, when we come to consider the origins of speech plans this version of the theory still leads us into a logical dead end.59 Presumably speech plans could themselves be intended or unintended. If they are intended, they must require a plan, and we are back in the Akins–Dennett regress. If, on the other hand, speech plans are unintended, Hoffman’s theory leads us to conclude that they should be experienced as alien and, presumably therefore, the speech that follows from them would be experienced as alien also.

  The answer to these conundrums is not to reject Hoffman’s proposal that auditory hallucinations are inner speech, but to look more carefully at the processes involved in recognizing that thoughts and images are self-generated.

  How we Recognize the Real

  Most of us take for granted the process of distinguishing between our thoughts and images and the things we hear or see. The experiences of people who hallucinate remind us that the mechanisms responsible for this process are anything but self-evident. There are good philosophical and scientific reasons for supposing that we do not have a priori knowledge of whether a perceived event is something that we have generated by ourselves, or something that is generated by an agency or process external to the self.

  The philosophical argument follows from Ludwig Wittgenstein’s analysis of the difficulties involved in describing our mental states. We saw in Chapter 7 that emotional states cannot be identified by brute introspection, because they do not come with appropriate labels attached to them. Similarly, ther
e is no reason to believe that perceptual states have the labels ‘real’ or ‘imaginary’ printed on them. We have to infer how best to describe any particular experience from whatever information there is available to us, and there is no unique source of information that we can rely on in order to make this judgement.

  Scientific research on our ability to discriminate between mental events (thoughts and emotions) and events in the world (someone speaking to us or standing in front of us) has been pursued over the last two decades by American experimental psychologist Marcia Johnson.60 Johnson calls this ability source monitoring and she has focused, in particular, on our ability to tell the difference between memories of things we have perceived and memories of things we have thought ourselves. As Johnson points out, professional scientists and artists often get into disputes following a failure of this kind of source monitoring. This usually results in someone claiming credit for an idea that originated from someone else, but occasionally the opposite kind of error can occur. (The songwriter Paul McCartney woke one morning with a tune that was later to be the hit song ‘Yesterday’ running through his mind, and spent days checking whether he had heard it from someone else.)61

  There is not enough space here to describe Johnson’s many elegant experiments. It is sufficient to say that she has shown that accurate source monitoring depends on a variety of cues. For example, we often make use of contextual information about time and location to decide whether an event has ‘really happened’. The inherent plausibility of the experience may also be important – if we recall ourselves performing acts that violate the laws of nature we are likely to realize that we are remembering a dream. Sensory qualities also play a role, since the more vivid our memory of an event, the more likely we are to believe that it really happened. Johnson has also shown that the mental operations we use when generating a thought may provide us with useful information. Try thinking of a vehicle beginning with C – it is probably not difficult to come up with an answer. Now try thinking of a vegetable beginning with O – most people find this much more difficult.* When thinking of the vegetable, you may have been aware of a feeling of ‘cognitive effort’ as you searched your mind for an appropriate exemplar. At a later time, you will be able to remember this feeling, which will help you recognize that you were not told the name of the vegetable in question, but thought of it yourself. (The role of cognitive effort explains Paul McCartney’s confusion about the authorship of ‘Yesterday’. Apparently, the composition of the song had not been accompanied by the cognitive effort necessary for him to realize that the song was his.)