Disorders of perception

1. DISORDERS OF
PERCEPTION
Dr. Priyash Jain
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2. CONTENT
• Introduction
• Sensory distortion
• Changes in intensity
• Changes in quality
• Changes in spatial characteristics
• Sensory deception
• Illusion
• Hallucination
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3. INTRODUCTION
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4. INTRODUCTION
• The word perception is derived from the Latin word “percipio”
meaning “to seize, understand”
• Perception - process of attaining awareness or understanding
of the environment by organizing and interpreting sensory
information.
• Sensation is only the first stage in receiving information from
outside the self.
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5. INTRODUCTION
• Imagery is the internal mental representation of the world
and is actively drawn from memory. Conceptually, imagery is
sometimes designated as a residual trace of sense perceptions.
• Imagery underlies our capacity for many crucial cognitive
activities such as mental arithmetic, map reading, visualizing
and imagining places previously visited and recollecting
spoken speech.
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6. INTRODUCTION
Normal perception Imagery
Concrete reality Are figurative
Occur in external objective space Appear in inner subjective space
Clearly delineated Incomplete and poorly delineated
Sensory elements are full and
fresh
Sensory elements are relatively
insufficient
Constant and remain unaltered Dissipate and have to be recreated
Independent of our will Dependent on our will
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7. SENSORY DISTORTION
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8. SENSORY DISTORTION
• Changes in intensity
• Changes in quality
• Changes in Spatial form
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9. CHANGES IN INTENSITY
• Increased intensity of sensations (hyperaesthesia) may be the
result of intense emotions or a lowering of the physiological
threshold.
• Thus a person may see roof tiles as a brilliant flaming red or
hear the noise of a door closing like a clap of thunder.
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10. CHANGES IN INTENSITY
• Anxiety and depressive disorders as well as hangover from
alcohol and migraine are all associated with increased
sensitivity to noise.
• Even day-to-day noises such as washing crockery are
magnified to the point of discomfort.
• Those who are hypomanic, suffering an epileptic aura or
under the influence of lysergic acid diethylamide (LSD) may
see colours as very bright and intense.
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11. CHANGES IN INTENSITY
• Hypoacusis occurs in delirium, where the threshold for all
sensations is raised.
• Visual and gustatory sensations may also be lowered in
depression, for example, everything is black or all foods taste
the same.
• Changes in intensity can also be a feature of intense normal
emotions such as religious fervour or the unsurpassed
happiness of being in love.
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12. CHANGES IN QUALITY
• It is mainly visual perceptions that are affected by this,
brought about by toxic substances.
• Coloring of yellow, green and red have been named
xanthopsia, chloropsia and erythropsia.
• These are mainly the result of drugs (for example, santonin,
poisoning with mescaline or digitalis) used in the past to treat
various disorders.
• In derealization everything appears unreal and strange, while
in mania objects look perfect and beautiful.
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13. CHANGES IN SPATIAL FORM
• Refers to a change in the perceived shape of an object.
• In micropsia patient sees objects as smaller than they really
are. The opposite kind of visual experience is known as
macropsia or megalopsia.
• The experience of the retreat of objects into the distance
without any change in size is porropsia.
Micropsia Macropsia
Normal
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14. CHANGES IN SPATIAL FORM
• Dysmegalopsia can result from retinal disease, disorders of
accommodation and convergence but most commonly from
temporal and parietal lobe lesions.
• Rarely, it can be associated with schizophrenia.
• In oedema of the retina visual elements are separated so that the
image falls on what is functionally a smaller part of the retina
than usual. This gives rise to micropsia.
• Scarring of the retina with retraction naturally produces
macropsia, but as the distortion produced by scarring is usually
irregular, metamorphopsia is more likely to result.
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15. DISTORTIONS OF THE
EXPERIENCE OF TIME
• From the psychopathological point of view there are two
varieties of time: physical and personal, the latter being
determined by personal judgement of the passage of time.
• It is the latter that is affected by psychiatric disorders.
• We are all aware of the influence of mood on the passage of
time, so that when we are happy ‘time flies’, and when we are
sad it passes more slowly.
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16. DISTORTIONS OF THE
EXPERIENCE OF TIME
• In severe depression the patient may feel that time passes
very slowly and even stands still. Slowing down of time is
most marked in those with psychotic depressive symptoms.
• By contrast the manic patient feels that time speeds by and
that the days are not long enough to do everything.
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17. DISTORTIONS OF THE
EXPERIENCE OF TIME
• Some patients with schizophrenia believe that time moves in
fits and starts, and may have a delusional elaboration that
clocks are being interfered with.
• In acute organic states, disorders of personal time are shown
in temporal disorientation and in milder forms there may be
an overestimation of the progress of time.
• Some patients with temporal lobe lesions may complain that
time either passes slowly or quickly.
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18. DISTORTIONS OF THE
EXPERIENCE OF TIME
• In recent years there is some evidence to suggest that patients
with schizophrenia have abnormalities of time judgement,
estimating intervals to be less than they are.
• Age disorientation is another feature present in patients with
chronic schizophrenia, noted even in the absence of any other
features of confusion.
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19. SENSORY DECEPTIONS
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20. SENSORY DECEPTIONS
• These can be divided into
• illusions, which are misinterpretations of stimuli arising from
an external object, and
• hallucinations, which are perceptions without an adequate
external stimulus.
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21. ILLUSIONS
• In illusions, stimuli from a perceived object are combined with
a mental image to produce a false perception.
• It is unfortunate that the word ‘illusion’ is also used for
perceptions that do not agree with the physical stimuli, such
as the Muller-Lyer effect in which two lines of equal length
can be made to appear unequal depending on the direction of
the arrowheads at the end of each respectively.
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22. ILLUSIONS
• Not indicative of psychopathology since they can occur in the
absence of psychiatric disorder, for example the person
walking along a dark road may misinterpret innocuous
shadows as threatening attackers.
• Illusions can occur in delirium when the perceptual threshold
is raised and an anxious and bewildered patient misinterprets
stimuli.
• Visual illusions are the most common
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23. ILLUSIONS
• Completion illusions: these depend on inattention such as
misreading words in newspapers or missing misprints because
we read the word as if it were complete.
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24. ILLUSIONS
• Affect illusions: these arise in the context of a particular mood
state. For example, a bereaved person may momentarily
believe they ‘see’ the deceased person, or the delirious person
in a perplexed and bewildered state may perceive the innocent
gestures of others as threatening.
• Pareidolia: this is an interesting type of illusion, in which
vivid illusions occur without the patient making any effort.
These illusions are the result of excessive fantasy thinking
and a vivid visual imagery.
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25. ILLUSIONS
• Cannot be explained as the result of affect or mind-set, so that
they differ from the ordinary illusion.
• Pareidolias occur when the subject sees vivid pictures in fire
or in clouds, without any conscious effort on his part and
sometimes even against his will.
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26. ILLUSIONS
Illusion should be distinguished from the following conditions-
• Fantastic Illusion – In this, patient sees extraordinary
modifications of his or her environment. One of the classic
example is a patient who looked in the mirror and instead of
seeing his own head he saw that of a pig.
• Intellectual Misinterpretations – These are basically wrong
deductions and do not imply alteration in the actual sense
perception. Here the object is perceived in exactly a same way,
but a wrong interpretation has been put on it. For e.g. when some
one says that the doctor is not really a doctor but the public
prosecutor.
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27. ILLUSIONS
• Perceptual Misinterpretations: It involves making a mistake
as to the nature of perception without that perception being
particularly influenced by emotion mixed with fantasy (Sims,
2009).
• Trailing phenomena, although not strictly illusions, are
perceptual abnormalities in which moving objects are seen as
a series of discreet and discontinuous images. They are
associated with hallucinogenic drugs.
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28. ILLUSIONS
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29. HALLUCINATIONS
• ‘A false perception which is not a sensory distortion or a
misinterpretation, but which occurs at the same time as real
perceptions’. (JASPERS)
• perceptions from ‘within’, although the subject reacts to them
as if they were true perceptions coming from ‘without’.
• This distinguishes them from vivid mental images that also
come from within but are recognized as such.
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30. CAUSES OF HALLUCINATIONS
• Intense emotions or psychiatric disorder,
• Suggestion,
• Disorders of sense organs,
• Sensory deprivation and
• Disorders of the central nervous system.
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31. HALLUCINATIONS OF
INDIVIDUAL SENSES
• Auditory
• Visual
• Olfactory
• Gustatory
• Tactile
• Special Hallucinations
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32. AUDITORY HALLUCINATIONS
• Auditory hallucination may be elementary and unformed, and
experienced as simple noises, bells, undifferentiated whispers
or voices.
• Elementary auditory hallucinations can occur in organic
states and noises, partly organised as music or completely
organised as hallucinatory voices, in schizophrenia.
• Auditory hallucinations may be abusive, neutral or even
helpful in tone. At times they may speak incomprehensible
nonsense or neologisms.
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33. AUDITORY HALLUCINATIONS
• Imperative hallucinations - The voices sometimes give
instructions to the patient, who may or may not act upon
them; these are also termed as “command hallucinations”
• Running commentary - In some cases the voices speak about
the person in the third person and may give a running
commentary on their actions. It was once thought to be
diagnostic of schizophrenia, this is no longer the case.
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34. AUDITORY HALLUCINATIONS
• Thought echo - hearing one’s own thoughts spoken aloud
Known in German as Gedankenlautwerden, it describes
hearing one’s thoughts spoken just before or at the same time
as they are occurring. Echo de la pensée (French) is the
phenomenon of hearing them spoken after the thoughts have
occurred.
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35. AUDITORY HALLUCINATIONS
Other types of Auditory Hallucinations
• Musical hallucination: Auditory hallucination characterized
by songs, tunes, melodies, harmonics, rhythms, and/or
timbres. The most common cause is acquired deafness. Other
causes include stroke, epilepsy and neoplasm, depressive
illness, OCD, alcoholism and schizophrenia.
• Talky-Talky Tongue: In this special kind, patient hallucinate
speech movement and hear speech which comes from their
own throat but has no connection with their thinking.
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36. AUDITORY HALLUCINATIONS
• A number of patients (becoming fewer in number with
advances in treatment) have continuous hallucinations that
do not trouble them.
• For others the persistence of the hallucinations cuts across all
activities so that the patient is seen to be listening and even
replying to them at times. Sometimes activity may diminish
due to preoccupation with the hallucinations.
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37. AUDITORY HALLUCINATIONS
• Patients explain the origin of the voices in different ways.
They may insist that the voices are the result of witchcraft,
telepathy, radio, television, and so on.
• Sometimes they claim that the voices come from within their
bodies such as their arms, legs, stomach.
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38. VISUAL HALLUCINATIONS
• These may be elementary in the form of flashes of light, partly
organized in the form of patterns, or completely organized in
the form of visions of people, objects or animals.
• Figures of living things and inanimate objects may appear
against the normally perceived environment or scenic
hallucinations can occur in which whole scenes are
hallucinated rather like a cinema film.
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39. VISUAL HALLUCINATIONS
• Brobdignagian hallucination: These are visual hallucinations
of gigantic objects or creatures. Also associated with delirium
and dementia.
• Peduncular hallucination: Cartoon-like visual hallucinations
without depth. They are typically colorful and nonthreatening
images of animals or people. They occur in full wakefulness
and last a few seconds or limits and rarely for hours or days.
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40. VISUAL HALLUCINATIONS
• Many varieties of visual hallucination are found in acute
organic states but small animals and insects are most often
hallucinated in delirium.
• Patients with delirium tremens are extremely suggestible so
that one may be able to persuade the patient to read a blank
sheet of paper.
• Scenic hallucinations are common in psychiatric disorders
associated with epilepsy
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41. VISUAL HALLUCINATIONS
• Visual hallucinations are isolated and do not have any
accompanying voices. Sometimes, however, visual and
auditory hallucinations co-occur to form a coherent whole.
• Patients with temporal-lobe epilepsy may have combined
auditory and visual hallucinations.
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42. VISUAL HALLUCINATIONS
• Some patients with schizophrenia of late onset (especially
when the illness is protracted) may see and hear people being
tortured, murdered and mutilated.
• In some patients, micropsia affects visual hallucinations so
that they see tiny people or objects, so-called Lilliputian
hallucinations. These are often accompanied by pleasure and
amusement.
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43. VISUAL HALLUCINATIONS
• Visual hallucinations are more common in acute organic
states with clouding of consciousness than in functional
psychosis.
• Visual hallucinations are extremely rare in schizophrenia, so
much so that they should raise a doubt about the diagnosis.
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44. OLFACTORY HALLUCINATIONS
• Hallucinations of odor can occur in schizophrenia and organic
states and, uncommonly, in depressive psychosis.
• Sometimes the smell may be pleasant, for example when some
religious people can smell roses around certain saints; this is
known as the Padre Pio phenomenon
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45. OLFACTORY HALLUCINATIONS
• Aura in episodes of temporal lobe disturbance are often with
unpleasant odour such as burning paint or rubber.
• At times, the hallucination may occur without any fit so that
the patient then complains of a strange smell in the house.
• For example one patient with a temporal lobe focus had no fits
but, from time to time, would complain of a smell of stale
cabbage water in the house and would turn the house upside
down trying to locate the offending object.
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46. GUSTATORY HALLUCINATIONS
• Hallucinations of taste occur in schizophrenia and acute
organic states but it is not always easy to know whether the
patient actually tastes something odd or if it is a delusional
explanation of the effect of feeling strangely changed.
• Depressed patients often describe a loss of taste or state that
all food tastes the same.
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47. TACTILE HALLUCINATIONS
• Three main types: superficial, kinaestethic and visceral.
• Sims further divides superficial hallucinations, which affect
the skin, into four types:
• thermic (e.g. a cold wind blowing across the face),
• haptic (e.g. feeling a hand brushing against the skin),
• hygric (e.g. feeling fluid such as water running from the head
into the stomach) and,
• paraestethic (pins and needles), although the latter most often
have an organic origin.
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48. TACTILE HALLUCINATIONS
• Kinaestethic hallucinations affect the muscles and joints and
the patient feels that their limbs are being twisted, pulled or
moved. They occur in schizophrenia, where they can be
distinguished from delusions of passivity by the presence of
definite sensations.
• Vestibular sensations such as sinking in the bed or flying
through the air can also be hallucinated and are best regarded
as a variant of kinaestethic hallucinations and occur in
organic states, most commonly delirium tremens.
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49. TACTILE HALLUCINATIONS
• Kinaestethic or vestibular perceptions occur in organic states
such as alcohol intoxication and during benzodiazepine
withdrawal and may also occur in the absence of any
abnormality
• Visceral hallucinations are seen in patients with chronic
schizophrenia and they may complain of twisting and tearing
pains.
• These may be very bizarre when the patient complains that
his organs are being torn out or the flesh ripped away from his
body.
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50. SPECIAL KINDS OF
HALLUCINATION
• Functional Hallucinations
• Reflex Hallucinations
• Extracampine Hallucinations
• Hypnogogic and Hypnopompic Hallucinations
• Organic Hallucinations
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51. FUNCTIONAL AND REFLEX
HALLUCINATIONS
Functional Hallucination Reflex hallucination
Hallucination is in the same
modality as the stimulus
Hallucination is in different
modality as compared to the
stimulus
chronic schizophrenia chronic schizophrenia, LSD,
Mescaline
Eg. Sound of fan  Auditory
hallucination
Sound of fan  Visual
Hallucination
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52. AN ILLUSION OR A FUNCTIONAL
HALLUCINATION?
• Both occur in response to an environmental stimulus but in a
functional hallucination both the stimulus and the
hallucination are perceived by the patient simultaneously, and
can be identified as separate and not as a transformation of
the stimulus.
• This contrasts with an illusion in which the stimulus from the
environment changes but forms an essential and integral part
of the new perception.
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53. EXTRACAMPINE
HALLUCINATION
• The patient has a hallucination that is outside the limits of
the sensory field.
• For example, a patient sees somebody standing behind them
when they are looking straight ahead
• Hearing voices talking in Kolkata when the patient is in
Indore.
• These hallucinations can occur in healthy people as
hypnagogic hallucinations but also in schizophrenia or organic
conditions, including epilepsy.
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54. HYPNOGOGIC AND HYPNOPOMPIC
HALLUCINATIONS
• Hypnogogic - occur when the subject is falling asleep
• Hypnopompic – when the subject is waking up.
• It has been suggested that hypnopompic hallucinations are
often hypnagogic experiences that occur in the morning when
the subject is waking and dosing-off again, so that they
actually happen when the subject is falling asleep.
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55. HYPNOGOGIC AND HYPNOPOMPIC
HALLUCINATIONS
• Hypnagogic hallucinations occur during drowsiness, are
discontinuous, appear to force themselves on the subject and do
not form part of an experience in which the subject participates
as they do in a dream.
• Hypnagogic visual hallucinations may be geometrical designs,
abstract shapes, faces, figures or scenes from nature. Auditory
hallucinations may be animal noises, music or voices.
• One of the most common is that of hearing one’s name called or a
voice saying a sentence or phrase that has no discoverable
meaning.
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56. HYPNOGOGIC AND HYPNOPOMPIC
HALLUCINATIONS
• About three times more common than hypnopompic
hallucination, although the latter are a better indicator of
narcolepsy.
• Subjects often assert that they are fully awake. This is not so
and electroencephalogram (EEG) records show otherwise.
• They are not indicative of any psychopathology even though
they are true hallucinatory experiences.
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57. ORGANIC HALLUCINATIONS
• Organic hallucinations can occur in any sensory modality and
they may occur in a variety of neurological and psychiatric
disorders.
• Organic visual hallucinations occur in eye disorders as well as
in disorders of the central nervous system and lesions of the
optic tract. Complex scenic hallucinations occur in temporal
lobe lesions.
• Charles Bonnet syndrome consists of visual hallucinations in
the absence of any other psychopathology, although impaired
vision is present.
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58. ORGANIC HALLUCINATIONS
• The phantom limb is the most common organic somatic
hallucination of psychiatric origin.
• The patient feels that they have a limb from which in fact they
are not receiving any sensations either because it has been
amputated or because the sensory pathways from it have been
destroyed.
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59. ORGANIC HALLUCINATIONS
• In rare cases with thalamo−parietal lesions the patient
describes a third limb.
• In most phantom limbs the phenomenon is produced by
peripheral and central disorders.
• Phantom limb occurs in about 95% of all amputations after
the age of 6 years.
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60. ORGANIC HALLUCINATIONS
• Occasionally a phantom limb develops after a lesion of the
peripheral nerve or the medulla or spinal cord.
• The phantom limb does not necessarily correspond to the
previous image of the limb in that it may be shorter or consist
only of the distal portion so that the phantom hand arises
from the shoulder.
• Equivalent perceptions of phantom organs may also occur
after other surgical procedures such as mastectomy,
enuleation of the eye, removal of the larynx or the
construction of a colostomy.
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61. ORGANIC HALLUCINATIONS
• When the experience is related to a limb the perception
shrinks over time, with distal parts disappearing more quickly
than those that are proximal.
• Lesions of the parietal lobe can also produce somatic
hallucinations with distortion or splitting-off of body parts.
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62. BODY IMAGE DISTORTION
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63. BODY IMAGE DISTORTIONS
• Hyperschemazia, or the perceived magnification of body parts.
• The perception of body parts as absent or diminished is known
as aschemazia or hyposchemazia.
• Paraschemazia or distortion of body image is described as a
feeling that parts of the body are distorted or twisted or
separated from the rest of the body.
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64. BODY IMAGE DISTORTIONS
• Some patients show bizarre attitudes to their paralysed limb,
known as somatoparaphrenia (delusional beliefs about the
body). They may have too many, they may be distorted,
inanimate, severed or in other ways abnormal (Halligan et al,
1995).
• They may claim the limb belongs to a specified other person.
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65. TO SUMMARIZE
• Perception is the process of attaining awareness or
understanding of the environment by organizing and
interpreting sensory information.
• In distortions there is a constant real perceptual object, which
is perceived in a distorted way, while in sensory deceptions a
new perception occurs that may or may not be in response to
an external stimulus.
• Illusions and Hallucinations are a type of sensory deception.
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66. REFERENCES
• CASEY PATRICIA KELLY BRENDAN. FISH'S CLINICAL
PSYCHOPATHOLOGY: signs and symptoms in psychiatry.
CAMBRIDGE UNIV Press; 2019.
• Oyebode F. Sims' symptoms in the mind: textbook of
descriptive psychopathology. Edinburgh: Elsevier; 2018.
• Ralston S, Penman I, Strachan M, Hobson R. Davidson's
principles and practice of medicine.
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67. THANK YOU
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