This document discusses perception and disorders of perception. It begins by defining perception as the first stage of receiving information from the outside world through the sensory systems. Perception involves an active process of transforming raw sensory stimuli into meaningful information. Disorders of perception can include sensory distortions, where real objects are perceived in a distorted way, or sensory deceptions like illusions and hallucinations, where new perceptions may or may not be in response to external stimuli. The document then examines different types of perceptual disorders in more detail, covering visual, auditory, tactile and other sensory modalities. It discusses the characteristics of illusions versus hallucinations and provides examples of different kinds of perceptual disorders.

1. BY-
Dr. Sameeksha Das
PGT first year.

2.  Whatisperception
 Disordersofperception
 Briefideasaboutillusionandhallucination

3. First stage of receiving
information from outside
the self.
 Sensory system includes the
 Visual
 Auditory
 Olfactory
 Gustatory
 Kinaesthetic
 Proprioceptive pathways

4.  These pathways deal with the receipt,
transformation and transmission of raw and
disparate sensory data from peripheral
receptors to CNS.

5. The transformation of raw
sensory stimuli into sensory
information that is then decoded
into meaningful perception at
the cortical level.
Involves active processes that are
influenced by
 Attention
 Affect
 Cultural expectations

6.  Context
 Prior expectations
 Memory
 Prior concepts
Perception is an active process that
involves the construction of an external
world that depends on internal templates.

7. STIMULUS INTACT
SENSATION
IMPAIRED
PERCEPTION

8. Internal representation of
the world and is actively
drawn from memory.
 Jaspers (1962) described the formal
characteristics of images as follows
 figurative, subjective.
Appear in inner subjective space
 not clearly delineated, incomplete

9. Sensory elements are insufficient
Dissipate, have to be recreated.
Actively created and are dependent
on will.
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.

10. Perception of an object,
presented in one sensory
modality, at the same time
as in a different sensory
modality.
 Rare condition, not an abnormal experience.
 Grapheme to colour; time unit to colour;
musical sounds to colour; general sound to
colour ; and , phoneme to colour.

11.  These experience are spatially extended,
close to the body , within limb’s reach, and
within ‘peri-personal space’.
 Consistent over time, specific and
elementary.

13.  Sensory Distortion- real perceptual object
which is perceived in a distorted way.
 Sensory Deception- new perception that
may or may not be in response to external
stimuli.

14.  Sensory distortions
a) Visual perception
b) Auditory perception
c) Tactile perception
d) Splitting of perception
 Sensory deceptions
a) Illusions
b) Hallucinations
c) Pseudo hallucinations.

15.  Disturbance of the mental state with/without
organic brain pathology
 Involve any elementary aspects of perception
like uniqueness , size , shape, color ,location,
motion or general quality.
Perceived object is correctly recognized and
identified yet there is a deviation from its
customary appearance.

16. Color,intensity
Shape and
size
Motion/general
quality
location
uniqueness

17. Changes in spatial form
 Alteration in the customary shape of
perceived object.
 Dysmegalopsia
 Retinal disease,disorders of accomodation
and convergence,temporal & parietal lobe
lesions
 Rare association with schizophrenia.
 May occur in poisoning with atropine or
 hyoscine

19.  Macropsia : size of perception is large.
 Micropsia : size of perception is small.
 Hemimicropsia : apparent reduction in one hemi
field of vision – temporal lobe epilepsy
 Palinopsia : recurrence or prolongation of visual
phenomenon beyond the customary limits of
appearance of the real event
eg: “cat noticed in the street one day kept
appearing at various times and situation over the
next few days”
Palin – again (Greek)
 Paraprosopia :when metamorphopsia affect
faces.

22. Changes in intensity
 Visual hyperasthesia: increased intensity
of colour.
hypomania, epileptic aura and influence of
LSD.
 Acrometopsia :complete absence of colour
unilateral/bilateral occipital lesions (lingual,
fusiform gyri)
 Dyschromatopsia : perversion of colour
perception
unilateral posterior lesions

23. •Hyperaesthesia

24. •Complete absence of color

25. Spatial location
 Telopsia : subjects appearing far away
 Pelopsia : subjects appearing nearer.
 Alloaesthesia :when the perceived
object is in a different position
 Akinetopsia: unable to perceive the
motion of the object. seen in B/L posterior
cortical damage.
 Eg: ‘ she had difficulty in pouring tea into a
cup because the fluid appeared to be
frozen’.

27. Changes in quality
 Colouring of yellow- xanthopsia,green-
chloropsia & red- erythropsia.
-poisoning with digitalis
 Derealization : everything appears unreal
and strange.
Eg: a factory worker sees a grass hopper
and becomes disturbed and excited at the
site of this very strange and unknown animal.

28.  Uniqueness of perception
Palinacousis : persistence of sounds that
are heard
 Intensity of perception
 Hyperacusis : increased sensitivity to noise.
Anxiety & depressive disorders, migraine,
hangover from alcohol.
 Hypoacusis: threshold for noise is raised
Delirium, depression & attention-deficit
disorder.

29.  Unable to form the usual, assumed links
between two or more perceptions.
 Rare phenomenon
 Described sometimes with organic states &
also with schizophrenia
Eg: a patient watching television
experienced a feeling of competition
between the visual and auditory perceptions

30.  Psychopathological point of view
 Physical- Determined by physical events
 Personal- Personal judgement of passage of
time
 Mania- Time passes quickly
 Depression- Time passes slowly
 Acute Schizophrenia- personal time goes in
fits and starts
 Acute organic states (temporal
disorientation)
 Overestimation of passage of time.

31. illusion
hallucination
Misinterpre
tations of
stimuli
from
external
object
Perceptions
without
adequate
external
stimulus

32. Stimuli
from
perceived
object
Mental
image
False
perception

33.  Completion Illusion – These depends on
inattention eg.misreading words in
newspapers.
‘-ook’ maybe read as book instead of look.
 Affect Illusion- These arise in the context of
particular mood state.
 Pareidolia – vivid illusions without the
patient making any effort ; result of
excessive fantasy thinking and a vivid visual
imagery.

36.  IntroducedbySir ThomasBrownein1646
 Derivationlatinwordalucinari meaningtowander inthemind.

37.  A perception without an object
(Esquirol)1817).
-doesnot cover functional hallucination or exclude dreams
 A false perception which is not a sensory
distortion or a misinterpretation ,but which
occurs at the same time as real
perceptions(Jaspers ,1962).
 A hallucination is an exteroceptive or
interoceptive percept that does not correspond
to an actual object (smythies ,1956).

38.  A hallucination is a perception without an object
or the appearance of an individual thing in the
world without any corresponding material event
(cutting 1997).
 According to Slade (1976) ,3 criteria are
essential (a) percept like experience in the
absence of external stimuli, (b) percept like
experience that has the full force and impact of
a real perception (c ) percept like experience
that is unwilled ,occurs spontaneously and
cannot be readily controlled by the percipient.

39.  Intense emotions
 Suggestion
 Disorders of sense organs
 Sensory deprivation
 Disorders of CNS
 Psychiatric disorders

40.  depressed patients -delusions of guilt; voices
reproaching,hallucination - disjointed or
short phrases – “rotter” ; “kill yourself”.
 continuous persistent hallucinatory voices in
severe depression ? Schizophrenia /physical
disease.

41.  Normal subjects can be persuaded to
hallucinate .
 By hypnosis or brief task motivation
instructions.

42.  Hallucinatory voices -in ear disease
 Visual hallucination - eye diseases ,disorders
of the CNS
 Peripheral lesions -sense organs -
hallucinations in organic states

43.  incoming stimuli reduced to minimum -
normal subject -hallucinate after few hours
changing visual hallucinations ,repetitive
phrases
 BLACK PATCH DISEASE delirium following
cataract extraction in the aged result of
sensory deprivation and mild senile brain
changes
 Deafness causes paranoid disorders in the
deaf.

44.  Lesions of diencephalons and cortex can
produce hallucination that are not only visual
but can be auditory.

45. Parameter Types
Depending on sensory
modality
Auditory,visual,olfactory,gustatory,t
actile, vestibular, deep sensations.
Depending on complexity Simple : single sense modality
Complex: Multiple sensory modality
involved.
Depending on organisation Unformed: sparks of light, noises
Formed: voices accusing the
patient.
Depending on reality value True hallucinations have reality
value
False hallucination pt. is aware of
the unreality of his perception.
Special types of
hallucinations
Hypnogogic , hypnopompic
,functional ,extracampine ,scenic
etc.

46.  Hearing
 Vision
 Smell
 Taste
 Touch
 Pain and deep sensation
 Vestibular sensations
 The sense of presence

48.  Hearing (auditors) may be elementary or
unformed.
 Elementary – noises, bells or undifferentiated
whispers ; in organic states
 Partly organized- music
 Completely organized- hallucinatory voices-
schizophrenia- persecutory in nature
 Severe depression ‘voices’ heard , less well
formed than schizophrenia

49. Imperative hallucination
 Voices sometimes give instructions to the
patient.
 may or may not act upon them
Auditory hallucinations may be
 Abusive
 Neutral
 Helpful
 Incomprehensible nonsense
 Neologism

50.  Thought echo - hearing one’s own thoughts
being spoken loud, voice may come from
inside or outside the head.
i. GEDANKENLAUTWERDEN- thoughts spoken
at the same time or before they are
occurring.
ii. ECHO DE LA PENSES- thoughts are spoken
just after they occurred.
 Running commentary hallucinations are
usually abusive.

52.  Elementary- flashes of light
 Partly organized- patterns
 Completely organized- people,
animals,objects.
 all varieties of VH in acute organic states
but small animals and insect most common in
delirium
 Scenic hallucinations- like a cinema
in psychiatric disorders with epilepsy.

53.  Patients with visual and auditory
hallucinations co occur as a whole
 Temporal lobe epilepsy
 Late onset of schizophrenia (protracted)
 Micropsia+ VH = tiny people or objects
Lilliputian hallucinations. Accompanied by
pleasure and amusement.

54.  Visual Hallucinations - organic states
+clouding of consciousness >functional
psychosis
 rare -schizophrenia
 Occasionally without any psychopathology
CHARLES BONNET SYNDROME

55.  Presents with visual hallucinations in the absence of
any psychopathology or brain disease.
 Victims are usually old age persons with visual loss.
 No other psychotic symptoms and aware about the
unreality of the perceptions.

57. Seen in
 Schizophrenia
 Organic states like temporal lobe
epilepsy(aura)
 Depression (uncommon)
PADRE PIO PHENOMENON- religious people
can smell roses around certain saints

59. Seen in
 Schizophrenia
 Organic states
Depressed patient often describes loss of taste.

61.  Formication- animals crawling over the
body;
in organic states
 Cocaine bug – formication + delusion of
persecution - cocaine psychosis
 Sexual Hallucinations- acute and chronic
schizophrenia

62.  Classified into 3 types (Sims)
1. Superficial
2. Kinesthetic
3. Visceral

63.  Superficial: Affecting skin sensation
 Thermic - heat and cold (‘my feet on fire’)
 Haptic - of touch (‘a dead hand touched
me’)
 Hygric – a perception of fluid (‘ I can feel a
water level in my chest’)
 Paraesthetic – pins and needles ; most often
have an organic origin.

64.  Kinaesthetic hallucinations : The patient
feels that his limbs are being bent or twisted
or his muscles squeezed.
 Schizophrenia
 Withdrawal state from benzodiazepine or
alcohol intoxication.
Eg: ‘I thought my life was outside my feet
and made them vibrate’

65.  Visceral hallucinations
 Twisting and tearing pains
 Very bizarre complaints- organs ripped out ,
flesh ripped from his body
 chronic schizophrenia

66.  Organic states
 Schizophrenia
 Conversion disorder
 Normal people – fervently religious

67.  Aka hallucinosis
 Persistent hallucinations in any sensory modality
in the absence of other psychotic features.
 Alcoholic hallucinoisis
 Occur during period of relative abstinence
 Usually auditory – threatening or reproachful,
sometimes benign.
 Sensorium is clear.
 Rarely persist longer than 1 week.
 Associated with long standing alcohol misuse.

68.  Organic hallucinosis
 20-30% patients of dementia
 Especially Alzheimer type
 Auditory or visual
 Disorientation and memory impairment.

69.  Hallucinations with insight (Hare, 1973)
 Vivid internal images
 phenomenon that have all the clarity and
vividness of a normal percept except that
they occur in inner subjective space.
 Lack the substantiality of the perceptions
 Full consciousness
 Retained unaltered
 Independently of the subject’s will, cannot
be deliberately evoked.

70.  Auditory, tactile or visual.
 Not necessarily pathological.

71.  Functional hallucinations :hallucination
requires the presence of another real
sensation.
 Auditory stimulus causes the hallucination,
both experienced
 Chronic schizophrenia
 Reflex Hallucination : a stimulus in one
sense modality produces hallucination in
another. Morbid variety of synaesthesia.

72.  Extracampine hallucination : Hallucinations
that is outside the limits of the sensory field.
o Seen in healthy people as hypnagogic
hallucination
o Schizophrenia
o Organic conditions- epilepsy

74.  Autoscopy (phantom mirror image) –
experience of seeing oneself and knowing
that it is oneself
VH+Kinesthetic +somatic sensation.
 Normal subjects- emotionally disturbed,
tired and exhausted
 depressed
 Hysteria
 Schizophrenia

75.  Acute and sub acute delirious states
 Epilepsy
 Focal lesions in parieto-occipital region
 Drug addiction
 Chronic alcoholism
NEGATIVE AUTOSCOPY
 No image in the mirror; organic state.
INTERNAL AUTOSCOPY
 Subject sees their own internal organs.

76.  Occur when the subject is falling asleep
during drowsiness
 Are discontinuous
 Appears to force themselves on the subject
 Do not form part of an experience in which
the subject participates unlike DREAM
 Commonest is auditory.
 geometrical designs , abstract shapes , faces
, figures or scenes from nature
 EEG shows alpha rhythm.

77.  Occurs when the subject is waking up
 Hallucinations persisting from sleep when the
eyes are open
 More in narcolepsy.

78.  Occurs in any sensory modality and may
occur in various neurological or psychiatric
disorders
 Depends on
i. General condition of the brain
ii. Recent experiences
iii. Psychodynamic factors
iv. Effect of local lesion

79.  Stimulation of visual projection areas in the
walls of the calacrine fissure causes
perception of flashes of light as does
stimulation or irritation of optic radiation.
 Lesions of optic tract and lateral geniculate
bodies.
 Spontaneous V H – sensory defect
 Complex scene hallucination – stimulation of
posterior part of temporal lobe.

81. Almost exclusively the result of lesion which
produces sensory defect
PHANTOM LIMB
 Most common organic somatic hallucination
 95% of amputation after 6 yrs of age
 Pt feels he sees the limb from which in fact
he is not receiving any sensations either
because limb has been amputated or sensory
pathway destroyed.

83.  Most phantom limbs are produced by peripheral and
central disorders.
 Occasionally it develops from lesion of peripheral
nerve or the medulla or spinal cord.
 Thalamoparietal lesions have phantom third arm or
leg.
 Does not necessarily correspond to the previous
image of the limb, maybe shorter.

84.  Whistling , buzzing, drumming and even bells
heard by patients with middle ear disease or
internal disease
 Caused by epileptic foci and space occupying
lesions in the temporal lobes

85.  Occurs most often in temporal lobe epilepsy
ass with salivation and chewing and sniffing
 Stimulating the depths of the sylvian fissure
around the transverse temporal gyri.
OLFACTORY HALLUCINATIONS
 temporal lobe epilepsy.

86.  These are multisensory hallucinations but
they do not include somatic hallucinations,
which is to be expected because the somatic
sensory area is separated from the temporal
lobe by sylvian fissure.

87.  Hyperschemazia –
percieved
magnifications of
body parts
 When part of the
body feels larger
than the normal
 ORGANIC CAUSES
o Brown Sequard
Syndrome
o PVD, MS, thrombosis
of PICA
 NON ORGANIC
CAUSES
o Hypochondriasis
o Conversion disorder
o Depersonalization

88.  Aschemazia- perception of body parts as
absent
 Hyposchemazia – Body parts as diminished
 Paraschemazia – distorted of body image as a
feeling that body parts are distorted or
twisted from rest of the body.
 Hemisomatognosia- Unilateral lack of body
image in which the person behaves as if one
side of body is missing

89.  Anosgnosia- ‘denial of illness’ –Rt hemisphere
strokes denied their knowledge early after
stroke and refused to admit to any weakness
in their left arm.
 Somatoparaphrenia- delusional beliefs about
the body, distorted, inanimate , severed, or
in any other ways abnormal.

90.  Fish’s Clinical Psychopathology- Patricia
Casey and Brendan Kelly
 SIMS’ Symptoms in the Mind- Femi Oyebode
 Synopsis Of Psychiatry-Benjamin James
Sadock, Virginia Alcott Saddock

91.  “You see, but you do not observe. The
distinction is clear.” – Sherlock Holmes

92. Thank
you !