Hallucination- Seeing What Isn’t There

Dr. V.K.Maheshwari, M.A(Socio, Phil) B.Se. M. Ed, Ph.D

Former Principal, K.L.D.A.V.(P.G) College, Roorkee, India

A hallucination is a fact, not an error; what is erroneous is a judgment based upon it.”

~Bertrand Russell

Hallucination is ‘seeing what isn’t there, or a sensory experience of something that does not exist outside the mind, caused by various physical and mental disorders, or by reaction to certain toxic substances, and usu. manifested as visual or auditory images.

It is the sensation caused by a hallucinatory condition or the object or scene visualized., a false belief or impression; illusion; delusion in more technical terms, to hallucinate is to think of remote objects with sensory vividness.

Delusions are false or erroneous beliefs that usually involve a misinterpretation of perceptions or experiences. Their content may include a variety of themes (e.g., persecutory, referential, somatic, religious, or grandiose).

Delusions are a symptom of some mental disorder, such as schizophrenia, delusional disorder, schizoaffective disorder, and schizophreniform disorder. Hallucinations, on the other hand, tend to only appear in people with schizophrenia or a psychotic disorder.

Persecutory delusions are most common; the person believes he or she is being tormented, followed, tricked, spied on, or ridiculed

Referential delusions are also common; the person believes that certain gestures, comments, passages from books, newspapers, song lyrics, or other environmental cues are specifically directed at him or her.

The distinction between a delusion and a strongly held idea is sometimes difficult to make and depends in part on the degree of conviction with which the belief is held despite clear contradictory evidence regarding its veracity.

Although bizarre delusions are considered to be especially characteristic of schizophrenia, “bizarreness” may be difficult to judge, especially across different cultures. Delusions are deemed bizarre if they are clearly implausible and not understandable and do not derive from ordinary life experiences. Delusions that express a loss of control over mind or body are generally considered to be bizarre; these include a person’s belief that his or her thoughts have been taken away by some outside force , that alien thoughts have been put into his or her mind , or that his or her body or actions are being acted on or manipulated by some outside force .

Hallucination may or may not be accompanied by delusion, by belief in the physical reality and presence of the object hallucinated. The more vivid and persistent the hallucination is, the more apt the subject to believe in the reality and presence of the object. Probably most normal persons have occasionally hallucinated; but persistent hallucination is one of the most common symptoms of mental disorder.

It is not possible to draw any sharp line between hallucination and illusion, or false interpretation of sense-impressions because it is not sure that some sense-impressions does not play a part in the genesis of hallucination; but in practice we speak of illusion when the role of sense-impression is obvious, of hallucination when it is doubtful or of secondary importance.

At best, imagination may be an apotheosis, radiating from a source from the vaults of mind or contained there within a … boundary, where the imaginer may feel as more or less being in control of what is being imagined, organizing or potentially directing the images that pop up about behind the eyes, and perhaps masterly unfolding them further for own use and or for others,

while hallucination may be a dazzling invasion by an image or by images, in mind or as if outside before the eyes, where the person will sort of uncontrollably be exposed to such an invasion of image-s.

It seems to me that images at best may calmly glowingly be managed in the mind of the imaginer, perhaps in a delightful entertaining way; also, images may be sought transferred into narration or … into drawn or painted or in other way manufactured pictures.

Hallucinations may evoke some weird feelings, they may make you spectacularly dazzled or even scared; they may much provoke your outer behaviour so that somebody witnessing you may get feeling worried, may decide that you need help, may try and help you find a therapy, or may help you get confined within the bounds of a madhouse.

Hallucination can be classified into three forms, these are reproductive, constructive and creative hallucinations.

Reproductive  Hallucination

Reproductive  hallucination is perhaps the most frequent variety, and lends itself most readily to a simple theoretical interpretation. Some times a person in good health who has for  any reason repeatedly perceived some object or impression, or very similar objects, may seem to perceive the same object again when it is no longer present.

Kinds of Hallucination.

Hallucinations are sensations that appear real but are created by your mind. They can affect all five of your senses. For example, you might hear a voice that no one else in the room can hear or see an image that is not real. Hallucination may be of a single sense or of several at once. the latter combined hallucinations are similar to dreams, and are always accompanied by the so-called clouded or dream-like consciousness.

Auditory hallucinations

Auditory hallucinations are among the most common. You might hear someone speaking to you or telling you to do certain things. The voice may be angry, neutral, or warm. Other examples of this type of hallucination include hearing sounds, like someone walking in the attic, or repeated clicking or tapping noises.

Auditory hallucinations are usually phonemes, verbal hallucinations or “Voices” and the words heard are frequently neologisms, nonsense words created by the patient.

Visual Hallucinations

Visual hallucinations involve seeing things that aren’t there. The hallucinations may be of objects, visual patterns, people, and/or lights. For example, you might see a person who is not in the room or flashing lights that no one else can see.

Visual hallucinations may be of absent friends or relatives, angles, god, the devil, snakes, insects, written words or other symbols.

Hallucinations of taste and smell

Olfactory hallucinations involve your sense of smell. You might smell an unpleasant odor when waking up in the middle of the night or feel that your body smells bad when it doesn’t. This type of hallucination can also include scents you find enjoyable, like the smell of flowers.

Hallucinations of taste and smell are usually disagreeable, for example of poison in food, poisonous gases, or filth. They may lead to refusal of food.

Tactile hallucinations

Tactile hallucinations involve the feeling of touch or movement in your body. For example, you might feel that bugs are crawling on your skin or that your internal organs are moving around. You might also feel the imagined touch of someone’s hands on your body.

Hallucinations of pain

Hallucinations of pain are often described as prods, pricks, stabs, darts or electric shocks, or the patient may describe ghis experience by a neologism.

Kinaesthetic or motor hallucinations.

The patient may think he has moved when no actual movement has taken place; for example, he may feel as if raised from the bed or as if flying. If they are intense, the false sensation may be transformed into an actual involuntary movement; and the patient may ascribe this movement to demonical possession vision of a single object, the Aristotelian illusion, and the geometric optic illusions. These normal illusions will not be considered further here.

Theories of Hallucination

There are numerous theoretical explanations for hallucination. Few important ones are as follows:

The theory of secondary sensations.

According to Sidis all hallucinations belong to the same order of phenomena as synesthesia. In other words, hallucinations are unusual and intense secondary sensations. This author defines perception and a combination of primary and secondary sensations; and in hallucination the secondary very much outweigh the primary in intensity, though the latter are never wanting. Normal perception, synesthesia, illusion, and hallucination represent merely four different degrees of intensity of the secondary in comparison with the primary sensations.

Centrifugal theories.

A .Psychical  hallucinations are vivid memory ideas projected outward. this is the view of Griesinger, Taine, and may of the older authors. Keaepelin also  has a group of “Apperception hallucinations” which he explains in this way. The following objections have been urged against the psychical centrifugal theory:

(a) There is a radical qualitative difference between intense images and sensations or perceptions; and (b) This view is based upon the theory of “Eccentric projection,” namely, that things are perceived int eh brain and then projected outward. (See James’s criticism)

b. Sensorial or physiological. “Hallucination is cramp of the sensory nerves” due to heightened excitability of subcortical centers or to weakened cortical inhibition. The objections are as follows:

(a) It would have to be a coordinated cramp of many sensory nerves in order to explain the combination of sensation in the hallucination; and

(b) Refluent or efferent currents in the sensory nerves are questionable, and the response of the sense organ to such currents doubtful.

. Centripetal theories.

Centripetal theories. these tend as a rule to deny the validity of Esquirol’s distinction between illulsions and hallucinations.

a. Binet’s “Point de repere” theory. There is alwyas an external object, howerer small, to serve as a starting point for hallucinatins as for illusion.

b.The physiological conception of the point de reparse. The afferent process may originate in the sense organ, sensory nerve, or even the sensory projection field, instead of being initiated be an external stimulus as in Binet’s theory. Kraepelin explains his “Elementary sense deceptions” and “Perception phantasms” in this way; and the occasional occurrence of unilateral hallucinations seems to favour the theory. The main objection is that afferent processes no matter how initiated can explain only the sensory char acted of the hallucination, and cannot account for its particular content or the fact that it is false.

Dissociation theories.

All the facts go to show that the hallucinations occurs in a dissociated state (Parish); and its content and falsity are no doubt due to this neural dissociation, that is to variation in synaptic resistance which results in the stimulus flowing into unusual cortical channels. Some form of dissociation is fundamental in the theories of Wernicke, James, Freud, and Prince.

a. Wernicke’s theory of hallucination is based upon the hypothesis of “Sejunction,” a temporary or permanent interruption of the paths followed by the nervous impulse. the nervous energy thus accumulates above the lesion; and, if the accumulations is in the psycho-sensory projection center, it sets up an abnormal irritation resulting in hallucination.

b. James’s theory is similar to Wernicke’s. Perception and ideation have the same cortical localization; but in ideation of the centers are not aroused to full activity, as the stimulation is drained off to other centres. If the flow is blocked (dissociation), the nervous energy accumulates, reaches a maximum intensity, and hallucination results.

c. Freud’s theory is based upon the activity of an unconscious mind. Hallucinations are symbolical pictureisations of the represses wishes, that is, wishes dissociated by conflict with the personal consciousness. Freud’s account is purely psychological, and from this standpoint may be correct. In other words, a a dissociated consciousness may exist and a hallucination may be a fulfilment of a wish; but this does not relieve one from the necessity of giving an explanation in neurological terms also. this theory explains only the content of the hallucination.

d. Prince believes that hallucinations may often be due to tge emergence into consciousness of  co-conscious (dissociated) images. These images although vivied remain independent of the main stram of consciousness. that is to say they are hallucinations.

Brain activity during hallucinations

Which brain areas are involved in experiencing a hallucination? Researchers havetried to answer this question with the use of modern functional neuro-imaging techniques, Neuro-imaging studies reveal a distributed network of cortical and sub-cortical areas involved in the experience of hallucinations. Although the exact role of these areas is not clear yet, it could be hypothesized that hallucinations are triggered by activity in sub-cortical and frontal areas, which in turn project to modality-specific association cortex, thereby leading to a conscious perceptual experience. With respect to auditory hallucinations, some studies observe activity in language-production areas during auditory hallucinations, some studies observe activity in the primary auditory cortex, but all studies report activity in the temporal lobe, more specifically in the middle or superior gyri. For visual hallucinations, activity is observed in secondary visual cortex.

Mechanism of hallucination.

Four approaches can be distinguished  regarding the mechanism of hallucination. These approaches focus respectively on

Inner speech

Most individuals report the experience of “inner speech” (either occasionally or continuously) when they think. Some hallucinating patients indicate that they cannot distinguish well between their inner speech and the “voices” they hear.

In addition, sub-vocal muscle activity has been reported, associated with hallucinations The “inner-speech” hypothesis of hallucinations holds that some distortion in the production of inner speech leads to the erroneous interpretation that the “inner speech” is of non-self origin.

Speech perception

According to Hoffman (Hoffman et al., 1999) a dysfunction of the speech perception system underlies auditory-verbal hallucinations. In the analysis of every-day sound characteristics, there is an important degree of acoustic ambiguity, due to background noise, and due to the “pasting” of phonemes (also called “blurring”). Syntactical and semantically expectations, based on earlier learnt words, therefore play a crucial role in speech perception. Hoffman’s hypothesis is that hallucinations arise from an impairment in verbal working-memory, Theory and findings which leads to pronounced linguistic expectations that could generate spontaneous perceptual “outputs”.

Reality monitoring

“Source monitoring” refers to the ability to distinguish between different sources of information, e.g., whether something was read in a newspaper, or whether it was told by a friend.

Reality discrimination and reality monitoring are considered to belong to this category of processes. Reality discrimination refers to distinguishing between internally generated information and externally presented information

Thus, reality discrimination refers to the “online” distinguishing of external versus internal sources, whereas reality monitoring refers to information that was presented or generated in the past. Reality discrimination measured  found that hallucinating patients made significantly more errors than non-hallucinating patients (specifically, the hallucinating patients erroneously indicated that a word had been presented in a burst of white noise).

Mental imagery

In the 19th century, Fancis Galton wrote that mental imagery exists as a continuum in the population, ranging from a total absence of mental images (subjectively) to imagery of great intensity and vividness, ending in pure hallucination (Galton, 1883). A number of studies investigated the imagery hypothesis with inconsistent results. The fact that none of the studies included adequate behavioral measures may account for this inconsistency.

The hypothesis that imagery and perception are more alike (and therefore harder to discern from each other) due to increased sensory characteristics of mental images in individuals that experience hallucinations thus predicts that these subjects will show smaller performance differences between a perception and an imagery condition of the same task.

Integrating the various perspectives

Despite the differences between these four cognitive approaches, there is also some conceptual overlap, which makes the possibility of integration especially attractive. Indeed, it could be argued that two earlier theories, namely the proposals of Frith  and of Grossberg incorporate elements of more than one approach.

Frith’s theory can be seen as an integration of the “inner speech” hypothesis and the reality monitoring hypothesis. According to Frith, hallucinations arise from failures in the monitoring of own intentions during inner speech (sometimes called ‘selfmonitoring’ by Frith). As a consequence, the cognitive system does not recognize that inner speech originates from the self, and thus erroneously attributes it to a non-self source. Thus, this approach does not consider the production of inner speech to be impaired, but rather states that auditory hallucinations are derived from defective monitoring of inner speech.

A different approach to hallucinations has been described by Grossberg (2000), based on the finding that top-down perceptual expectations can importantly affect the detection of stimuli

Grossberg  recently hypothesized, under normal behavioral conditions, a volitional signal can be phasically turned on that can alter this balance to favor top-down excitation, which can create conscious experiences in the absence of bottom-up information. In this way, conscious mental imagery can arise. In addition, Grossberg  proposes a mechanism by which hallucinations in schizophrenia could arise, namely when the phasic volitional signal becomes chronically hyperactive. As a result, top-down sensory expectations can generate conscious experiences that are not under the volitional control of the individual who is experiencing them. The net effect is a hallucination

This theory integrates elements of the imagery hypothesis and is reminiscent of Hoffman’s statement that “pronounced linguistic expectations can generate perceptual outputs”.

Most cognitive theorists agree that hallucinations are misattributions of internally generated information to an external source. Different hypotheses have been developed, concerning the role of inner speech, speech perception, reality monitoring, and mental imagery.

Diagnosis of Hallucination

Because many factors can trigger hallucinations, the best thing to do is to call the doctor right away if you suspect that your perceptions are not real. The doctor will ask about the symptoms and perform a physical exam. Additional tests might include a blood or urine test and perhaps a brain scan.

Causes of Hallucinations

Mental illnesses- are among the most common causes of hallucinations. Schizophrenia, dementia, and delirium are a few examples.

Substance abuse is another fairly common cause. Some people see or hear things that aren’t there after drinking too much alcohol or taking drugs like cocaine or PCP.

Lack of sleep can lead to hallucinations. social isolation, particularly in older adults

Medications taken for certain mental and physical conditions can also cause hallucinations. Parkinson’s disease, depression, psychosis, and epilepsy medications may trigger hallucination symptoms.

Other conditions that can cause hallucinations include, Terminal illnesses, such as AIDS, brain cancer, or kidney and liver failure, high fevers, especially in children, migraines, deafness, blindness, or vision problems, epilepsy (in some cases, epileptic seizures can cause you to see flashing shapes or bright spot

Treatment of Hallucinations

If you know someone who is hallucinating, avoid leaving them alone. Fear and paranoia triggered by hallucinations can lead to dangerous actions or behaviors. Stay with the person at all times and go with them to the doctor for emotional support. You may also be able to help in answering questions about their symptoms and how often they occur


Treatment for  hallucinations will depend entirely on their underlying cause. For example, if you are hallucinating because of delirium due to severe alcohol withdrawal, your doctor might prescribe medication that slows down your nervous system. For psychosis, the treatment may be a different kind of medication like dopamine antagonists.

Psychological Counselling

Counselling might also be part of your treatment plan, particularly if the underlying cause of  hallucinations is a mental health condition. Speaking with a counselor can help you get a better understanding of what is happening to you. A counselor can also help to develop coping strategies, particularly for when you are feeling scared or paranoid.







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