On the Plausibility of Psychotic Hallucinations

 

 

Paul Franceschi

University of Corsica

http://www.univ-corse.fr/~franceschi

 

preprint

 

p.franceschi@univ-corse.fr

 


 

Abstract

In this paper, we describe several factors that can contribute, from the patient's viewpoint, to the plausibility of psychotic complex hallucinations. We sketch then a Plausibility of Hallucinations Scale, consisting of a 25-item questionnaire, which aims at evaluating the degree of plausibility of hallucinations. We also emphasize the utility of pointing out to the patient the various factors that contribute to the plausibility of his/her hallucinations, in the context of cognitive therapy for schizophrenia.

 


 

On the Plausibility of Psychotic Hallucinations

We shall focus in what follows on the plausibility of psychotic hallucinations. My concern will be with providing an account of complex hallucinations encountered in psychosis that stresses multiple factors which reinforce, from the patient's viewpoint, their intrinsic plausibility. The purpose of this paper is then to expose how hallucinations can seem plausible and credible to the patient. In section 1, we describe several factors that contribute to the plausibility of hallucinations occurring in psychosis. We sketch then in section 2 a plausibility scale, designed to measure accurately the plausibility of hallucinations. In section 3, we point out what could be the impact on cognitive therapy for psychosis of the present account.

 

 

Factors of plausibility of hallucinations

 

We shall enumerate in what follows several factors that can contribute, from the patient's viewpoint, to the plausibility of the hallucinations that he/she experiences. Hallucinations are one major symptom of psychosis. According to DSM-IV, a hallucination is defined as "A sensory perception that has the compelling sense of reality of a true perception but that occurs without external stimulation of the relevant sensory organ". (DSM-IV, p. 767). By plausibility, we mean the fact that the patient's abnormal perceptions are seemingly attributable to an external source (usually, other people). The plausibility that results from certain phenomenological features of auditory hallucinations has notably been hinted at by Stephane et al. (2003):

 

(...) hearing "multiple voices" is associated with attribution of the "voices" to others, which is plausible intuitively as well. This indicates that the patients' experiences of hallucinations could be understood, intuitively, based on common sense experiences of the world.

 

In this paper, we shall expand this idea, by pointing out that multiple factors are susceptible of congruently strengthening the patient's conviction that his/her abnormal perceptions come from the external world.

Hallucinations come in a variety of modalities. In order to shed light on the factors that can lead to the plausibility of hallucinations occurring in psychosis, it is worth drawing first some useful distinctions.

 

Unimodal and multimodal hallucinations

 

Let us begin with the distinction between unimodal and multimodal hallucinations. Unimodal hallucinations can be classified into five types, corresponding to our five sensory pathways: auditory, visual, olfactory, tactile and gustatory. Multimodal hallucinations are made up of unimodal hallucinations of different types which occur simultaneously (or quasi-simultaneously). There are accordingly 26 combinations of multimodal hallucinations (plus 5 unimodal ones). These latter can be enumerated exhaustively as follows (we also describe an instance of some common multimodal cases, since it can be useful for explanatory purposes):

 

n-modal

case

instance

 

auditory

 

 

visual

 

1-modal

olfactory

 

 

tactile

 

 

gustatory

 

 

auditory-visual

"I saw x sitting on my bed and I heard him saying 'Bastard!'"

 

auditory-olfactory

"I heard x saying 'I will smoke a cigar!' and at this very moment I smell a taste of tobacco"

 

auditory-tactile

"I heard x saying 'You will be stung by a scorpion!' and at this very moment I felt a sharp sting of pain on my left arm"

 

auditory-gustatory

 

2-modal

visual-olfactory

"I saw x on my bed smoking a cigar and I also smell the taste of tobacco"

 

visual-tactile

"I saw a scorpion on my left arm and at this very moment I felt a sharp sting of pain there"

 

visual-gustatory

"I saw blood dripping from my finger and it had the taste of blood when I put it on my tongue"

 

olfactory-tactile

 

 

olfactory-gustatory

 

 

tactile-gustatory

 

 

auditory-visual-olfactory

 

 

auditory-visual-tactile

"I heard x saying 'You will be stung by a scorpion!' and at this very moment I saw a scorpion on my left arm while feeling a sharp sting of pain there"

 

auditory-visual-gustatory

"I heard 'I will harm you' and at this very moment I saw blood dripping from my finger and it had the taste of blood when I put it on my tongue"

 

auditory-olfactory-tactile

 

3-modal

auditory-olfactory-gustatory

 

 

auditory-tactile-gustatory

 

 

visual-olfactory-tactile

 

 

visual-olfactory-gustatory

 

 

visual-tactile-gustatory

 

 

olfactory-tactile-gustatory

 

 

auditory-visual-olfactory-tactile

 

 

auditory-visual-olfactory-gustatory

 

4-modal

auditory-visual-tactile-gustatory

"I heard 'I will harm you' and then I saw blood dripping from my finger, while I felt a sharp pain there. It had the taste of blood when I put it on my tongue"

 

auditory-olfactory-tactile-gustatory

 

 

visual-olfactory-tactile-gustatory

 

5-modal

auditory-visual-olfactory-tactile-gustatory

 

 

At this step, it should be noted that multimodal hallucinations retain their force from the plausibility that results from the simultaneous (or quasi-simultaneous) occurrence of two or more unimodal hallucinations of different types. For this reason, multimodal hallucinations retain considerable power with regard to unimodal ones. The sense of reality that emerges from multimodal hallucinations results from the fact that several sensory pathways are congruently involved in the hallucinatory process. Take the example of bimodal hallucinations of the auditory-visual type: the simultaneous occurrence of an additional visual hallucination strongly reinforces the sense of reality that emerges from the auditory hallucination. Consider if, in a single auditory hallucination, a patient hears the voice of John which insults him/her. Now consider if, instead of simply hearing the voice, the patient also sees simultaneously John sitting on his/her bed. This will result in a much greater sense of realism. This shows how multimodal hallucinations are seemingly highly more plausible and realistic than unimodal ones. More generally, it illustrates how (n+1)-modal hallucinations appear significantly more real than n-modal ones, a supplementary sensory pathway being involved in the hallucinatory process.

 

Factors of plausibility of auditory hallucinations

 

It is worth mentioning, to begin with, several factors that can contribute to the intrinsic plausibility of auditory hallucinations:

 

(a)          structured versus unstructured auditory hallucinations: structured sounds notably consist of comments on the patient's thoughts or activities, conversations of several persons, or commands ordering the patient to do things, etc., while on the other hand, unstructured sounds consist of ringing, buzzing, whistling, etc.

(b)   auditory hallucinations having an external versus an internal origin: auditory hallucinations seemingly coming out from outer space could reinforce the idea that the voices have an external origin, e.g. are attributable to other people.

(c)   the locus (Chadwick et al. 1996, p. 103) -- i.e. the space location -- of auditory hallucinations is also susceptible of reinforcing their intrinsic plausibility. For consider a patient who hears the voice of the presenter of the show saying 'Bastard!'. Now this sounds more realistic if the locus of the voice is the television device rather than the ashtray. Suppose now that the patient hears a voice saying 'I can read your thoughts'. Now it sounds more likely to the patient if the voice comes out from the telephone than from the halogen lamp. The locus of the auditory hallucination is then another factor which can contribute to the likeliness, from the patient's viewpoint, of psychotic hallucinations.

(d)   bilateral versus unilateral auditory hallucinations: auditory hallucinations coming indifferenlty from the patient's right or from his/her left are more plausible than unilateral ones.[1]

(e)   time location related versus unrelated to the patient's thoughts, emotions or actions (Stephane et al. 2003 make mention of the "relation to the moment").

(f)    phrases versus single words: in this context, phrases, conversations, elaborate sentences are more plausible than single words.

(g)   multiple voices versus single voice (Stephane et al. 2003).

(h)   auditory hallucinations fitting versus not fitting with the patient's desires or fears: this factor consists of whether the hallucinations experienced by a patient fit adequately or not with his/her individual fears or desires. For in the affirmative, it would greatly increase the plausibility of the corresponding hallucinations. To take an example. The patient is very anxious about the evolution of his/her illness. He/she hears a voice that says: "You will relapse next month". Now the content of this auditory hallucination fits adequately with the patient's own fears. The reason why auditory hallucinations fitting with desires or fears are more plausible, is that they are coherent with the patient's belief system. By contrast, had the content of auditory hallucinations been unrelated or contradictory with the patient's desires and fears, the corresponding information would have then resulted in a lack of coherence with the patient's belief system.

(j)          interactive versus noninteractive voices: whether the patient can interact or not with voices, i.e. discuss or engage in dialog with them.

 

Factors of plausibility of visual hallucinations

 

Several factors, on the other hand, can contribute to the intrinsic plausibility of visual hallucinations:

 

(a)   formed versus unformed visual hallucinations: formed hallucinations are made up of figures, faces, morphing objects or scenes. By contrast, unformed hallucinations consist of dots, lines, geometrical figures, flashes, etc.

(b)   ordinary versus bizarre or extraordinary visual hallucinations: for obvious reasons, objects that look ordinary gain more likeliness than bizarre, unreal objects.

(c)   objects in color versus in black and white.

(d)   visual hallucinations fitting versus not fitting with surroundings: as noted by Teunisse et al. (1996), the relationship to surroundings could play an important role in the plausibility of complex hallucinations. Such or such unimodal hallucination could fit well (e.g. a person lying on a bed, a scorpion walking on the ground) or not with surroundings (a figure on the ceiling). Now it should be apparent that fitting with surroundings visual hallucinations are consistent with the patient's knowledge of the physical world. This renders, from the patient's viewpoint, the hallucination very plausible. By analogy with the locus of auditory hallucinations, fitting with surroundings can be assimilated to the locus -- i.e. space location -- of visual hallucinations.

(e)   bilateral versus unilateral visual hallucinations.

(f)    time location of visual hallucinations related versus unrelated to the patient's thoughts, emotions or actions (e.g. the patient thinks to a scorpion and at this very moment he/she sees a scorpion on the ground).

(g)     animated versus static images.

 

 

 

Plausibility of hallucinations scale

 

From the above, it results that it could be useful to measure accurately the plausibility of hallucinations occurring in psychosis. For this purpose, we shall sketch now a 25-item scale, which is targeted at evaluating the plausibility of hallucinations experienced by a patient. This scale - which remains to be tested/validated - consists of a questionnaire which allows for 5 types of ratings: from never (0) to very often (4).

 

item

questions (0-4)

1

does the patient experience auditory hallucinations?

2

does the patient listen hallucinatory structured sounds?

3

does the patient experience auditory hallucinations which come out from outer space?

4

does the patient experience auditory hallucinations whose locus sounds realistic?

5

does the patient experience bilateral auditory hallucinations?

6

does the patient experience auditory hallucinations whose time location is related to the patient's thoughts, emotions or actions?

7

does the patient experience auditory hallucinations which consist of phrases, conversations?

8

does the patient experience auditory hallucinations with multiple voices?

9

does the patient experience auditory hallucinations whose content fits with his/her fears?

10

does the patient experience auditory hallucinations whose content fits with his/her desires?

11

can the patient interact with auditory hallucinations, i.e. discuss or engage in dialog with them?

12

does the patient experience visual hallucinations?

13

does the patient experience formed visual hallucinations?

14

does the patient experience visual hallucinations with ordinary objects?

15

does the patient experience visual hallucinations in color?

16

does the patient experience visual hallucinations whose locus fits with surroundings?

17

does the patient experience bilateral visual hallucinations?

18

      does the patient experience visual hallucinations whose time location is related to his/her thoughts, emotions or actions?

19

does the patient experience visual hallucinations consisting of scenes or sequences of animated images?

20

does the patient experience tactile hallucinations?

21

does the patient experience olfactory hallucinations?

22

does the patient experience gustatory hallucinations?

23

does the patient experience bimodal hallucinations (auditory-visual, auditory-olfactory, etc.)?

24

does the patient experience trimodal hallucinations (auditory-visual-olfactory, auditory-tactile-gustatory, etc.)?

25

does the patient experience quadrimodal hallucinations (auditory-visual-tactile-gustatory, auditory-olfactory-tactile-gustatory, etc.)?

 

It is worth noting that this 25-item scale can be regarded as non-specific to psychotic hallucinations. It is also suited to other disorders or illnesses involving hallucinations. Among these are other mental illnesses, but also Charles Bonnet syndrome (Teunisse et al. 1996, Menon et al. 2003), epilepsy (Sachdev 1998; Schwartz & Marsh 2000), etc. In particular, the Charles Bonnet syndrome occurs in the elderly and is usually associated with ocular pathology and severe visual impairment. The Charles Bonnet syndrome is characterized by the presence of complex and persistent visual hallucinations. The syndrome is usually associated with an absence of hallucinations in other sensory modalities. It is worth noting that the Charles Bonnet syndrome affects psychologically normal individuals with full or partial insight and the patients are accordingly non-delusional. On the other hand, auditory hallucinations are frequently associated with temporal lobe epilepsy, where hallucinations in other modalities can also occur.

It is worth mentioning that the Plausibility of Hallucinations Scale could also be used in association with other instruments for measuring insight, such as the Beck Cognitive Insight Scale (Beck et al. 2003) in order to gain more accurate knowledge of the patient's state. For psychosis is usually associated with lack of insight into the internal origin of the hallucinations. By contrast, in other illnesses such as Charles Bonnet syndrome, the patient usually retains insight into the internal origin of his/her hallucinations (these latter being often termed pseudo-hallucinations). Perhaps it could be helpful to use in association an instrument for measuring accurately the insight into hallucinations, i.e. the belief that the perceptual stimuli have an internal origin (the patient's 'brain playing tricks': Siddle 2002). The following scale could notably be used to measure specifically insight into hallucinations. It consists of a 8-item additional questionnaire, whose structure parallels that of the Plausibility of Hallucinations Scale:

 

item

questions (0-100)

1

do you believe that the auditory stimuli that you perceive have an external or an internal (your brain playing tricks) origin?

2

do you believe that the visual stimuli that you perceive have an external or an internal origin?

3

do you believe that the olfactory stimuli that you perceive have an external or an internal origin?

4

do you believe that the tactile stimuli that you perceive have an external or an internal origin?

5

do you believe that the gustatory stimuli that you perceive have an external or an internal origin?

6

do you believe that the bimodal (auditory-visual, auditory-olfactory, etc.) stimuli that you perceive have an external or an internal origin?

7

do you believe that the trimodal (auditory-visual-olfactory, auditory-tactile-gustatory, etc.) stimuli that you perceive have an external or an internal origin?

8

do you believe that the quadrimodal (auditory-visual-tactile-gustatory, auditory-olfactory-tactile-gustatory, etc.) stimuli that you perceive have an external or an internal origin?

 

In this context, one should normally expect that the plausibility of hallucinations rate and the insight into hallucinations be correlated. This should normally be the case for what concerns psychosis. But it seems also to be the case -- at a lesser degree -- for other illnesses involving hallucinations, such as Charles Bonnet syndrome. Along these lines, Teunisse et al. (1996) remarked that among 60 patients, "11 (18%) had sometimes being deceived for a short period, but this had happened only when hallucinated objects looked ordinary and fitted realistically in the surroundings". A similar remark is also made by Menon et al. (2003).

 

 

Impact on Cognitive Therapy

 

We suggest that the above emphasis on the plausibility of hallucinations could be usefully incorporated into the process of cognitive-behavior therapy of schizophrenia (Kingdon & Turkington 1994, Chadwick et al. 1996, Rector & Beck 2002). The general idea would be to point out to the patient who experiences highly plausible hallucinations the different factors that confer to his/her hallucinations their intrinsic plausibility. Hopefully, this would insert itself well into the process of cognitive-behavior therapy, whose primary goal is to help the patient gaining more insight into the nature of his/her hallucinations and in particular to understand that they do not originate from an external source. In this context, stressing to the patient the plausibility of his/her hallucinations, could help him/her understand better how hallucinations can be self-deceiving.

Let us focus, to begin with, on multimodal hallucinations. A first step would be to point out the patient that multimodal hallucinations are capable of seeming very plausible and realistic. It could then be argued and explained to the patient that multimodal hallucinations are more plausible than unimodal ones. This could be illustrated through some examples. This latter strategy could make use of 'what if statements' (Ellis & Dryden 1997). Suppose, could it be said, that someone experiences, as many people do, hallucinations. To take an example, suppose that a given person has an auditory hallucination. Now consider if instead of one single auditory hallucination, he/she experiences simultaneously one visual hallucination. Wouldn't this multimodal (of the auditory-visual type) hallucination sound more realistic than a single visual hallucination or than a single auditory one? Along these lines, it could be pointed out to the patient that the particular case of multimodal hallucination that he/she experiences is potentially very realistic and inherently capable of deceiving him/her.

Once the patient familiar with the concept of multimodal hallucinations, another goal could be to learn the patient how to use by herself the preceding taxonomy of multimodal hallucinations and to apply it when he/she experiences these types of complex hallucinations. He/she would then be capable of identifying the corresponding case at hand. Hopefully, this could help the patient rationalize his/her abnormal perceptions and perhaps accept better the internal origin of his/her hallucinations as an alternative explanation.

The utility of classifying multimodal hallucinations would be helpful to the patient, it seems, to help him/her rationalize and explain the phenomena he/she experiences. For we should bear in mind that the patient experiences abnormal phenomena, which are unfamiliar to psychologically normal people. In this context, helping the patient rationalize, classify and describe accurately the phenomena of his/her own internal world, appears then as a valuable practical goal to attain. Accordingly, identifying, recognizing and labeling a given type of multimodal hallucination could help lessen its associated omnipotence (Chadwick et al. 1996). This could be helpful to the patient, since it appears to be a better alternative than simply leave him/her with an unexplained and upsetting phenomenon. More generally, the fact of identifying the various factors that render his/her complex hallucinations so plausible could help the patient gain more insight into the internal origin of his/her hallucinations. At this step, it should be noted that the present account is notably in line -- for what concerns the delusion that consists in attributing an external origin to the hallucinations -- with the views emitted by Brendan Maher (1988, 1999), who sees delusions as a patient's attempt to explain some perplexing and puzzling phenomena. According to Maher, delusions arise from normal (mainly rational but occasionally irrational) reasoning applied to abnormal phenomena. Among these abnormal phenomena which are very perplexing to the patient are the hallucinations.

 

 

Directions for further research

 

Finally, the above developments suggest several questions, which could usefully be the subject of further study. A first question is as follows: (a) Is the plausibility of hallucinations rate higher in psychosis than in other illnesses involving hallucinations, e.g. other mental illnesses, Charles Bonnet syndrome, temporal lobe epilepsy, etc.? A comparison of the plausibility of hallucinations rate occurring in schizophrenia and other illnesses involving hallucinations could be made accordingly. We suggest that such comparison could provide some useful information about the relationships of these illnesses (Sachdev 1998). Although schizophrenia (paranoid subtype) should prima facie involve a higher rating, it seems that an accurate measure of the degree of plausibility of hallucinations could result in some interesting information. Along these lines, a comparison of the plausibility of hallucinations ratings occurring in different subtypes of schizophrenia could also be made.

The above Plausibility of Hallucinations Scale is also designed to allow for comparisons between different chronological states in the same patient. This suggests a second type of question: (b) Does the plausibility of hallucinations rating evolve during the course of schizophrenia? Along these lines, Nayani & David (1996) observed an increase in the complexity of auditory hallucinations over time, seemingly related to lesser distress and better coping. An additional question would also be: does the plausibility of hallucinations rating increase during the period that precedes a relapse? A similar question could be raised for other illnesses involving hallucinations. In this context, Menon et al. (2003) reported accordingly that "Elementary hallucinations may progressively evolve into complex visual hallucinations" in the Charles Bonnet syndrome.

The following types of question extend the two preceding questions to the correlation between the ratings of the plausibility of hallucinations and of the insight into hallucinations. It follows: (c) Is there a significant difference in the correlation of the plausibility of hallucinations rating and of the insight into hallucinations rating, in different illnesses involving hallucinations, and also in different subtypes of schizophrenia? And also: (d) Does this latter correlation evolve during the course of the illness in the same patient?

Lastly, a fifth interesting question goes as follows: (e) Is the plausibility rate of hallucinations occurring in schizophrenia correlated with the I.Q. of the patient, i.e. do patients with a high I.Q. more frequently experience complex hallucinations with a high level of plausibility? In other words, is the following hypothesis confirmed: The higher the I.Q., the higher the plausibility of hallucinations rating? Hopefully, the answer to these questions will provide some information that might well be useful to the understanding of the illness and to cognitive-behavior therapy of schizophrenia.

 

 

Acknowledgements

 

I thank Peter Brugger and Hélène Verdoux for very useful comments on an earlier version of this paper.


 

References

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[1] I owe the suggestion to include the bilateral/unilateral distinction related to hallucinations in all modalities to Peter Brugger.

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