2. Definition
• Perception (from the Latin perceptio, percipio)
is the organization, identification, and
interpretation of sensory information in order
to represent and understand the environment.
• Conscious awareness of elements in the
environment by the mental processing of
sensory stimuli.
3. Disorders of Perception
• Divided into
• Sensory Distortion- Constant real perceptual
object which is perceived in a distorted way
• Sensory Deception- new perception that may
occur that may or may not be in response to
external stimuli
4. Sensory distortions
• Changes in perception that are the result of :
1. Change in the intensity,
2. Quality of the stimulus ,
3. Spatial form of the perception,
4. Distortions of the experience of time,
5. Splitting of perception.
5. Changes in intensity
• Increased intensity of sensation- hyperesthesia
seen in increasing sensations or lowering of
physiological threshold.
Seen in
anxiety
depressive disorder,
Hangover from alcohol
Migraine
hypochondria cal personalities
6. • Increased sensitivity to noise – Hyperacusis is
associated with Anxiety and depressive
disorders as well as hangover from alcohol
and migraine.
• Decreased sensitivity to noise – Hypoacusis,
occurs in delirium, where the threshold for all
sensations is raised. Hypoacusis feature of
other disorders associated with attentional
deficits such as depression and attention-
deficit disorder.
7. Changes in quality
Visual perception
• Xanthopsia- Coloring of yellow
• Chloropsia - Coloring of green
• Erythropsia- Coloring of red
which is result of drugs (santonin, poisoning
with mescaline or digitalis)
8. Changes in spatial form
• Change in percieved shape of an object, can
result from
Retinal disease
Disorders of accommodation
Temporal and Parietal Lobe Lesions
Poisoning with Atropine and Hyoscine
SCHIZOPHRENIA
9. • Micropsia : a visual disorder in which the
patient sees objects
o Smaller than they really are
o Farther away than they really are
• Macropsia or Megalopsia : opposite to
micropsia
10. • Porropsia : Experience of retreat of subjects
into the distance without any change in space.
Edema of the retina.
Partial Paralysis of accomdation.
Diseases affecting the nerves controlling
accommodation.
11. • MACROPSIA : Scarring of retina with
retraction
and complete paralysis of accommodation.
• DYSMEGALOPSIA: Objects are perceived
larger in one side and smaller in the other.
Atropine, Hyoscine poisoning
Chronic arachnoiditis
• METAMORPHOSIA: Irregular in shape.
12. Distortions in the experience of time
Mania- Time passes quickly
Depression- Time passes slowly
Temporal lobe lesions- feels time either passes
slowly or quickly.
Schizophrenia- have abnormalities of time
judgment, estimating intervals to be less than
they are.
13. Splitting of perception
• Seen sometimes with organic states and with
schizophrenia
• Unable to form usual assumed link between
two or more perceptions
• While watching TV experiencing a feeling of
competition between the visual and auditory
perception and not coming out of the same
source.
14. Sensory deceptions
• Illusions- Stimuli from a perceived object are
combined with a mental image to produce a
false perception.
15. Types of illusion
• Complete Illusion- These depends on misreading
words in newspapers or missing misprints
because we read the word as if it were capable.
• Affect Illusion-These arise in the context of
particular mood state.
• Paradolia- vivid illusions occur without the
patient making any effort ; are the result of
excessive fantasy thinking and a vivid visual
imagery.
16. Hallucination
• A perception without an object. (Esquirol)
• A false perception which is not a sensory
distortion or a misinterpretation but which
occurs at the same time as real perceptions.
(Jaspers)
17. Causes of Hallucination
• Intense emotions
• Suggestion
• Disorders of sense organs
• Sensory deprivation
• Disorders of CNS
18. Intense emotions
• Very depressed patients with delusions of
guilt. Hallucination tend to be disjointed or
fragmentary, uttering single words or short
phrases
• persecutory nature and may consist of voices
giving a commentary on person’s actions and
discussing him in a hostile manner.
19. Disorders of a peripheral sense organ
• Hallucinatory voices may occur in ear disease
and visual hallucinations in diseases of the
eye,
• Charles Bonnet syndrome (phantom visual
images) is a condition in which complex visual
hallucinations occur in the absence of any
psychopathology and in clear consciousness,
• It is associated with either central or
peripheral reduction in vision.
20. Charles Bonnet syndrome
• Feature of delirium, dementia, organic
affective or delusional syndromes, psychosis,
intoxication or neurological disorders with
lesion of central visual cortex are absent,
• Hallucination are located in external space,
much more vivid than the patient’s impaired
vision would otherwise permit,
21. Charles Bonnet syndrome
• May be modifiable by voluntary control,
• Usually insight is there concerning their
unreality,
• Can be either elementary or complex.
( Podoll et al, 1990)
22. Sensory deprivation
• If all incoming stimuli are related to minimum
in a normal subject they will begin to
hallucinate after few hours
• Usually these are changing visual
hallucinations and repetitive phrases
• BLACK PATCH DISEASE delirium following
cataract extraction in the aged result of
sensory deprivation and mild senile brain
changes
23. Disorders of CNS
• Lesions of the diencephalons and the cortex
can produce hallucinations that are usually
visual but can be auditory.
24. Hallucinations of individual senses
• Hearing
• Vision
• Smell
• Taste
• Touch
• Pain and deep sensation
• The sense of presence
25. Hearing
• Hearing (auditors) may be elementary or
unformed.
• Elementary – noises, bells or undifferentiated
whispers ; in organic states
• Partly organized- music
26. Hearing
• Completely organized-’Voices’ are
characteristic of schizophrenia,
• Can occur at any stage of the illness,
• As well as occurring in organic states, such as
delirium or dementia,
• They can occasionally occur in severe
depression but usually less well formed than
those described in schizophrenia.
27. Hearing
Imperative/Command hallucination
• Voices sometimes act upon individuals and give
instructions.
• may or may not act upon them
• Voices speak about the person in the third person and
may give a running commentary on their actions,
although this was one thought to be diagnostic of
schizophrenia, this is no longer the case since these
symptoms have also been described in mania
(Gonzalez-Pinto et al, 2003),
• Running commentary hallucinations are usually
abusive.
29. Hearing
• Thought echo - hearing one’s own thoughts
being spoken loud, voice may come from
inside or outside the head.
i. GEDANKENAUTWERDEN- thoughts are
spoken at the same time or before they are
occurring.
ii. ECHO DE LA PENSES- thoughts are spoken
just after they occurred.
30. Vision
• Elementary- flashes of light
• Partly organized- patterns
• Completely organized- visions of people animals
or objects.
Scenic hallucinations- whole scenes are
hallucinated like a cinema film,
More commonly seen in delirium
Also seen in psychiatric disorders associated with
epilepsy.
31. Vision
• Visual hallucinations are more common in
acute organic states with clouding of
consciousness than in functional psychosis.
• Patients with temporal-lobe epilepsy may
have combined auditory and visual
hallucinations,
• Some patients with schizophrenia may see
and hear people being tortured, murdered
and mutilated.
32. Vision
• Occasionally visual hallucinations occur in the
absence of any psychopathology or brain
disease and Charles Bonnet syndrome must
then be considered as the most likely
differential diagnosis.
33. Smell (olfactory)
Seen in
• Schizophrenia
• Organic states like temporal lobe epilepsy are
often ushered in by an aura involving an
unpleasant odour such as burning paint or
rubber with or without fit.
• Depression (uncommon)
PADRE PIO PHENOMENON- religious people can
smell roses around certain saints.
35. Touch( Tactile)
• Formication- a feeling that animals are
crawling over the body; not uncommon in
organic states
• Cocaine bug – formication occurring with
delusion of persecution in cocaine psychosis
• Sexual Hallucinations- seen in acute and
chronic schizophrenia
37. Superficial
1. Thermic ( cold wind blowing across the face),
2. Haptic ( feeling a hand brushing against the
skin)
3. Hygric ( feeling fluid ),
4. Paraesthetic ( feeling pins and needles).
38. Kinaesthetic
• Affects muscles and joints
• Patient feels their limbs are being twisted
pulled or moved
• Seen in schizophrenics
• Organic states such as alcohol intoxication and
benzodiazepine withdrawal
39. Pain and deep sensation
• Visceral hallucinations (SIMS 2003).
• Twisting and tearing pains
• Very bizarre complaints- organs being ripped
out and flesh ripped from his body
• Seen in chronic schizophrenia
• Delusional zoopathy in which delusional belief
that there is an animal crawling about in the
body and also a hallucinatory component
since the patient feels it & can describe it in
detail.
40. Sense of presence
• Organic states
• Schizophrenia
• Hysteria
• Normal people – Reverently religious
41. Special kinds of hallucination
• Functional hallucinations:
• a auditory stimulus causes the hallucination,
but it is experienced as well as the
hallucination.
• Seen in Chronic schizophrenia.
42. Special kinds of hallucination
• Reflex hallucinations
• Synaesthesia is the experience of a stimulus in
one sense modality producing a sensory
experience in another,
• Can occur under the influence of
hallucinogenic drugs such as LSD or mescaline
when the subject might describe feeling,
tasting and hearing flowers simultaneously.
43. Special kinds of hallucination
• Extracampine hallucinations-Hallucinations
that is outside the limits of the sensory field.
• Seen in healthy people as hypnagogic
hallucination
• Schizophrenia
• Organic conditions- epilepsy
44. Special kinds of hallucination
• Autoscopy or phantom mirror-image- The
patient sees himself and knows that it is he.
Not just visual hallucination , because even
kinesthetic and somatic sensations are
present
• Normal subjects- emotionally disturbed, tired
and exhausted
• Hysteria
• Schizophrenia
45. • Acute and sub acute delirious states
• Epilepsy
• Focal lesions in parieto occipital region
• Toxic infective states whose effect is greatest
in basal regions of the brain
• Drug addiction
• Chronic alcoholism
46. • Negative autoscopy: patients look in the
mirror and see no image which is seen in
organic states,
• Internal autoscopy: subject sees their own
internal organs, although this is rare.
47. Hypnagogic and hypnopompic
hallucinations
• Hallucinations occur when the subject is falling
asleep or waking up respectively,
• Hypnagogic hallucinations is about three times
more common than hypnopompic hallucinations.
• Hypnopompic a better indicator of narcolepsy.
• Commonest is auditory. His name being called
• May be geometrical designs , abstract shapes , faces
, figures or scenes from nature
• EEG shows alpha rhythm
48. Phantom Limb
• Most common organic somatic hallucination.
• 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.
• In rare cases with thalamo−parietal lesions the
patient describes a third limb.
49. Hallucinatory syndromes
• Disorders in which there are persistent
hallucinations in any sensory modality in the
absence of other psychotic features.
1. Alcoholic hallucinosis :
Hallucinations are usually auditory.
Occur during periods of relative abstinence.
They may be threatening or reproachful.
Hallucinations rarely persist longer than 1 week.
Associated with long-standing alcohol misuse.
50. 2. Organic hallucinosis:
• Present in 20−30% of patients with
dementia, especially of the Alzheimer type,
• Most commonly are auditory or visual,
• There is also disorientation and memory is
impaired.
51.
52. THANK YOU
“ WE DON’T SEE
THINGS AS THEY ARE,
WE SEE THINGS AS WE
ARE.”
