1. Dr Deepthi V H

2.  Sensation : is the first stage in receiving information
from outside the self.
 Perception : occurs when a stimulus has undergone
processing according to its form, color, motion.
 The subject is able to recognize that an object is in his
field of vision- sensation intact
 He is unable to recognize what the object or its
function is - impaired perception

3.  Constant real perceptual object in a distorted
way…………sensory distortion.
 New perception that may or may not be in response
to an external stimulus………..sensory deception.

4.  Sensory distortions….a) Visual perception
b) Auditory perception
c) Splitting of perception
 Sensory deceptions …a) Illusions
b) Hallucinations
c) Pseudohallucinations.

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

6. Changes in spatial form
Metamorphopsia
 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.

7.  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”
 Paraprosopia :when metamorphopsia affect faces.

9. Changes in intensity
 Visual hyperasthesia: increased intensity of colour
 Acrometopsia :complete absence of colour
-unilateral/bilateral occipital lesions (lingual,
fusiform gyri)
 Dyschromatopsia : perversion of colour perception
-unilateral posterior lesions

10.  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’.

11. 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.

12.  Uniqueness of perception
Palinacousis : persistance 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.

13.  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

14. Physical and personal
Personal: Determined by personal judgement of passage
of time.
Influence of mood: happy-time flies, sad-slow
Affected by psychiatric disorder
Severe depression- time passes slowly
Mania- time speeds by

15.  Illusions : Misinterpretations of stimuli arising from an
external object
 Hallucinations :Perception without an adequate
external stimulus.

16.  Completion illusions: depends on inattention for their
occurrence.
‘ _ook’ misread as ‘Book’ though the faded letter was ‘L’
 Affect illusions: arise in context of particular mood
state.
Delirious person may perceive the innocent gestures as
threatening.
 Pareidolia: vivid illusions without patients effort.
Subject sees vivid pictures in fire or in clouds without
any conscious effort.

17.  A perception without an object (Esquirol 1817).
 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).

18.  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.

19.  Intense emotions.
 Disorders of sense organs
 Sensory deprivation
 Disorders of central nervous system.

20.  Auditory hallucinations
 elementary & unformed- bells, whistling, machinery or
rattles.
 Completely organized as hallucinatory voices
schizophrenia
 May also occur in chronic alcoholic hallucinosis or
affective psychosis occasionally

21.  Visual hallucination
 Elementary- in the form of flashes of light
 Partly organized- patterns
 Completely organized-visions of people, objects or
animals
 Occipital lobe tumours
 Post-concussional state
 Metabolic disturbances-hepatic failure
 Alzheimer’s disease, senile dementia

22.  Charles Bonnet’s syndrome( phantom images)-
Individuals experience complex visual hallucinations
in association with impaired vision without any
psychopathology or disturbance of consciousness
 More common in elderly
 Associated with central & peripheral reduction in
vision
 Importance in differential diagnosis.

23.  Delirium tremens
 Alcohol withdrawal syndrome characterized by gross
changes in perception, mood and conscious state.
 Pareidolic or affective illusions are often prodromal.
 Lilliputian hallucinations-seeing tiny people or objects.
accompanied by pleasure & amusement.

24.  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’)

25.  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’

26.  Olfactory hallucination: schizophrenia , epilepsy.
 Hallucination of smell which may or may not be
unpleasant.
 Eg : people are pumping anaesthetic gas into the house
which the patient alone can smell.

27. Gustatory hallucinations: schizophrenia, depression,
temporal lobe epilepsy, psychotropic drugs- lithium or
disulfiram.
Eg: In schizophrenia and depression the flavour of food
may disappear alltogether or become unpleasant.

28.  Autoscopy (phantom mirror image) : subjects see an
image of themselves in external space viewed from
within their own physical body.
 Negative autoscopy : for instance, the patient looks in
the mirror and sees no image at all.
 Extracampine hallucination (concrete awareness):
experienced outside the limits of the sensory field,
outside the visual field or beyond the range of
audibility
Eg:‘ I keep on hearing them talking about my disease
down in the post office’ (half a mile away)

29.  Hypnogogic hallucination: perceptions that occur
while going to sleep.
 Hypnopompic hallucination: perceptions that occur on
waking.
May be visual, auditory or tactile
Occur in many people in good health
Described with narcolepsy, cataplexy and sleep
paralysis.
Toxic states- glue sniffing , acute fever , post
infective depressive states.

30. Eg - ‘a feeling of someone pushing him over the bed’
or
‘seeing a man coming across the bedroom’

31.  Functional hallucination : External stimulus is
necessary to provoke hallucination but the stimulus is
experienced as well as the hallucination
Eg : ‘ A schizophrenic patient heard hallucinatory voices
only when water was running through the pipes’.
 Reflex hallucination : A stimulus in one sensory
modality producing a hallucination in another.
Eg : ‘ I can feel you writing in my stomach’

32.  SIMS’ Symptoms in the mind psychopathology, fourth
edition.
 Fish’s clinical psychopathology, third edition.

33. Thank you