2. Definitions
• Sensation: An immediate, unprocessed
stimulation of receptors of sense organs.
• Perception: Processing of sensory input,
organizing and interpreting it to produce a
meaningful experience of outside world.
• Apperception: To perceive new experience in
relation to past experience.
3. History
• Ideas from structuralism, constructivism, and
the philosophy of the mind.
• Between the 1950s and 1970s Gestalt
psychology.
5. Topics
Sensory distortions
– Changes in intensity
– Changes in quality
– Changes in spatial form (dysmegalopsia)
– Distortions of the experience of time
6. Sensory deceptions
– Illusions
• Definition
• Types of illusions
– Hallucinations
• Definition
• Causes
• Hallucinations of individual senses
• Hallucinatory syndromes
• Special kinds of hallucination
• The patients attitude to hallucinations
• Body image distortions
7. Sensory distortions
Real perceptual object in a distorted way.
Changes in the intensity and quality of the stimulus or the
spatial form of the perception.
8. Changes in intensity
Hyperaesthesia
• Increased intensity of sensations
• Intense emotions
• lowering of the physiological threshold.
• Eg. : Roof tiles as a brilliant flaming red .
Noise of a door closing like a clap of thunder.
• In :a. ↑Sensitivity of noise(hyperacusis)
anxiety and depressive disorders
hangover from alcohol
migraine
B. ↑ Sensitivity to colors
Hypomania, epileptic aura, LSD.
9. Hypoaesthesia
• Delirium
• Threshold for all sensations is raised.
• Defect of attention further reduces sensory
acuity.
• Depression and attention-deficit disorder.
• Visual and gustatory sensations may also be
lowered in depression, for example, everything
is black or all foods taste the same.
10. Changes in quality
– visual perceptions that are affected by this
– Etiology: Toxic substances.
• Coloring
xanthopsia> Yellow
Chloropsia> Green
Erythropsia> Red
Eg: Drugs like santonin, poisoning with mescaline or
digitalis.
– Metallic taste associated with the use of lithium.
– Derealisation: Everything appears unreal and strange.
– In mania objects look perfect and beautiful.
11. Changes in spatial form
(dysmegalopsia)
– Change in the perceived shape of an object/irregular.
– Metamorphosia
– Dysmegalopsia also seen in ,
• Temporal and parietal lobe lesions.
• Retinal disease, disorders of accommodation &
convergence.
• Aura or in the course of the fit.
• Atropine poisoning.
• Rarely in f20.
12. Micropsia
• Smaller than they really are.
• Oedema of the retina visual
• partial paralysis of
accommodation
Macropsia
• Bigger
• Scarring of the retina.
• Complete paralysis of
accommodation
• overactivity of
accommodation during near
vision
• If accommodation is normal
but convergence↓ =
macropsia occurs and vice
versa.
13. Lilliputian hallucinations
• People, objects or animals greatly reduced in
size
• Delirium, dementia.
• Toxoplasmosis.
• Basilar migraine, mesencephalic lesions.
• Schizophrenia and alcohol withdrawal states
14.
15. Distortions of the experience of time
– Two varieties of time:
• Physical and personal
• Personal judgment of the passage of time affected by psychiatric
disorders.
– Influence of mood on the passage of time,
1. In severe depression >time passes very slowly and even stands
still.
2. Manic >time speeds by.
3. Schizophrenic patients may >time moves in fits and starts, and
delusional elaboration that clocks.
4. In acute organic states>disorientation and overestimation of the
progress of time.
5. Temporal lobe lesions >time either passes slowly or quickly.
16. Sensory deceptions
• These can be divided into
– Illusions, which are misinterpretations of stimuli arising
from an external object.
– Hallucinations, which are perceptions - without an
adequate external stimulus.
17. Illusions
– Stimuli from a perceived object are combined with a
mental image to produce a false perception.
– Muller-lyer illusion: Not agreed with psychical stimuli.
– Not indicative of psychopathology.
– Delirium > patient misinterprets stimuli.
– Visual illusion (m.C.) F/b auditory illusions.
– Difficult to differentiate illusion or hearing of
hallucinatory voices.
– Fantastic illusions :extraordinary modifications to their
environment.
18. Types of illusion
Inattention such as misreading words in newspapers or
missing misprints.
Completeness, previous experience, our interests.
Completion Illusions
19. Affect illusions
Context of a particular mood state.
A bereaved person >‘See’ the deceased person
Delirious person in a bewildered/perplexed
state>Innocent gestures as threatening
In severe depression when delusions of guilt are
present > Wicked, people talking about killing him
when he is in the company of others.
20. Pareidolia
Occur without any effort, sometimes against will.
Excessive fantasy thinking and a vivid visual imagery.
Not explained as the result of affect or mind-set,
Pictures in fire or in clouds
22. Illusion vs Functional hallucination
Functional hallucination
• Both the stimulus and the
hallucination are perceived
by the patient
simultaneously
• Identified as separate and
not as a transformation of
the stimulus.
Illusion
• The stimulus from the
environment changes but
forms an essential and
integral part of the new
perception.
23. Trailing phenomena
• Moving objects are seen as a series of discreet and
discontinuous images.
• Hallucinogenic drugs(LSD, Peyote, Psilocybin, and
PCP)
24. Hallucinations
Definitions :
Esquirol: ‘A perception without an object’.
Jaspers : ‘A false perception which is not a sensory distortion or a
misinterpretation, but which occurs at the same time as real perceptions’.
Smythies:An hallucination is an exteroceptive or interoceptive percept
which does not correspond to an actual object.
Slades’s 3 criteria : a. Percept like experience in the absence of external
stimulus ,b. Full force and impact of real percept, c. Unwilled
spontaneously , can’t be controlled.
DSM 4 TR: A sensory perception , with a compelling sense of reality of a
true perception ,occurring without external stimulation of the relevant
sensory organ.
26. Hallucinations
• Causes(as a result of)
1. Intense emotions ,
2. Suggestion,
3. Psychiatric disorder,
4. Disorders of sense organs,
5. Sensory deprivation
6. Disorders of the central nervous system.
27. Emotion
Very depressed patients with delusions of guilt may
hear voices reproaching them.
Not continuous voices but disjointed or fragmentary
eg. ‘Die’ , ‘kill yourself’.
Continuous voices: schizophrenia or organic etiology.
28. Suggestion
– Normal subjects.
– Walking down a dimly lit corridor and stopping seeing a
faint light over the door at the end.
– Genesis of hallucinations /‘hysterical psychosis’.
– No longer mentioned in ICD−10 or DSM−IV and only of
historical interest.
29. Disorders of a peripheral sense organ
– Hallucinatory voices >ear disease
– Visual hallucinations > diseases of the eye
– CNS co morbidity
• For example, glaucoma patient with continuous visual
hallucinations >atherosclerotic dementia and left
posterior temporal lobe disease.
– Peripheral lesions of sense organs> hallucinations in
organic states .
– Negative scotomota >alcohol misuse.
30. Charles bonnet syndrome
• Phantom visual images.
• Absence of any psychopathology.
• In clear consciousness.
• Central or peripheral reduction in vision.
31. Sensory deprivation
• Incoming stimuli are reduced to a minimum in a normal
subject.
• Ex :
Deafness >paranoid disorders.
Protective patches in cataract surgery >delirium
32. Disorders of the central nervous
system
• Lesions of the diencephalons and the cortex> visual
hallucinations but can be auditory.
• Hypnagogic and hypnopompic hallucinations.
33. Hallucinations of individual senses
Auditory Visual Olfactory
Gustator
y
Tactile
Pain
and
deep
sensatio
n
Sense of
‘presence
’
34. Differential diagnosis
• Illusion
• Pseudo hallucination
• Hypnagogic images
• Hypnopompic images
• Vivid imagery
• Normal perception
• Delusion without a hallucination
35. Auditory hallucination
– Elementary >Noises, bells, undifferentiated whispers or voices. Seen in
organic cond . or noise.
Partly organized as music or completely organized as
hallucinatory voices, in schizophrenia.
– Hallucinatory Voices are basis for the patient’s delusion of
persecution.
• schizophrenia ,delirium ,dementia ,severe depression .
– Imperative hallucinations> Instructions to the patient.
– 3rd person AH or Running cmmentary.
36.
37. Thought echo/Thought
sonorisation
– Hearing one’s own thoughts
spoken aloud
• SCAN classifies thought
echo as a disorder of
thought (WHO, 1998)
rather than as a
hallucinatory experience.
• first-rank symptom
Thought broadcasting or
thought diffusion
• Thoughts are no longer private
but are accessible to others.
38. Talky-talky tongue
• Continuously auditorily hallucinated .
• Felt speech movements in her tongue.
• Thus she had both auditory and possibly somatic
hallucinations.
39. Delusional elaboration of a
hallucinatory experience
– Abusive the patient may attack those whom they believe are
responsible.
– Example > patient denied hearing voices but from time to time would
make unprovoked attacks on fellow patients.
40. Origin
• Junction between the right temporal lobe and the right parietal lobe.
• Inner-space hallucinations>increased white matter volume and posterior
displacement of sulcus , outer-space hallucination>decreased white
matter volume and anterior displacement.
<http://schizophreniabulletin.oxfordjournals.org/content/37/1/212.abstract>.
41. Vision
Elementary > flashes of light,
• Partly/ completely organized .
All varieties of visual hallucination are found in
– Acute organic states >delirium, delirium tremens .
associated with fear and terror.
– Scenic hallucinations are common in psychiatric disorders
associated with epilepsy
– Temporal-lobe epilepsy >combined auditory and visual
hallucinations
– Common in acute organic states with clouding of
consciousness than in functional psychosis.
– Extremely rare in schizophrenia.
42.
43. Smell (olfactory)
– Schizophrenia
– Organic states
– Uncommonly, in depressive psychosis.
• Difficult distinguishing hallucination from illusion and
delusion.
• Schizophrenia claim that they smell gas as enemies are
poisoning them by pumping gas into the room.
• Temporal lobe disturbance> aura involving an unpleasant
odor such as burning paint or rubber.
• Padre pio phenomenon>pleasant smell,eg.Religious people
can smell roses around certain saints.
44. Taste (gustatory)
– Schizophrenia and acute organic states .
– Delusional explanation .
– Depressed >loss of taste or state that all food tastes the
same.
45. Touch (tactile)
Formication > small animals crawling over the body
• Acute organic states.
• Cocaine bug (with delusions of persecution).
• Cold winds blowing >heat, electrical shocks and sexual
sensations, and the patient is convinced that these are
produced by outside agencies.
• Sexual hallucinations can occur in both acute and chronic
schizophrenia.
46. Sims classification of tactile
hallucinations
A. Superficial hallucinations, which affect the skin, into four types:
1.Thermic (e.g. A cold wind blowing across the face),
2.Haptic (e.g. Feeling a hand brushing against the skin),
3.Hygric (e.g. Feeling fluid such as water running from the head into
the stomach)
4.Paraestethic (pins and needles), although the latter most often
have an organic origin.
B. Kinaestethic hallucinations affect the muscles and joints and the
patient feels that their limbs are being twisted, pulled or moved.
C. Vestibular sensations such as sinking in the bed or flying through the
air - delirium tremens.
• Kinaestethic or vestibular >organic states such as alcohol intoxication
and during benzodiazepine withdrawal
47. Pain and deep sensation
• These are termed visceral hallucinations by Sims.
• Ex.
– Chronic schizophrenia may complain of twisting and tearing pains.
For example, sensations in his brain as layers of tissue were being
peeled off so as to bring to completion the battle between good and
evil.
– organic disorder, as in the patient who said he was infested with an
animal several centimetres long that he could feel in his stomach.
He eventually died and at post mortem was found to have a tumour
invading the thalamus.
48. Delusional zoopathy.
• Delusional belief that there is an animal crawling about in the
body.
• Hallucinatory component since the patient feels it
(hallucination) and can describe it in detail.
49. The sense of ‘presence’
– Difficult to classify an abnormal sense of presence because, although
it is not strictly a sense deception, it cannot be regarded as a delusion
either.
– Most normal people.
– Usually this is dismissed as imagination but nevertheless they look
behind them to be certain.
– However, sometimes there is the feeling that someone is present,
whom they cannot see, and may or may not be able to name. E.g.
A. I saw Jesus Christ at my side on feast day
• Lack of sleep, hunger and religious enthusiasm.
B. Hand on right shoulder(sense of presense)
– Healthy people,organic states,schizophrenia ,hysteria ,borderline
personality disorder.
50. Hallucinatory syndromes
– Hallucinosis > persistent hallucinations in any sensory
modality in the absence of other psychotic features.
– Alcoholic hallucinosis(during periods of relative
abstinence.)
• Sensorium is clear and hallucinations < 1 week .
• long-standing alcohol misuse.
– Organic hallucinosis >dementia(alzheimer type)
• Disorientation and memory is impaired .
51. Special kinds of hallucination
Functional hallucinations
Auditory stimulus but the stimulus is experienced as well as the
hallucination.
Hallucination requires the presence of ‘another ‘real sensation.
For example, a patient with schizophrenia first heard the voice
of God as her clock ticked; later she heard voices coming from
the running tap and voices coming from the chirruping of the
birds.
Patients can distinguish both features from each other and
crucially, the hallucination does not occur without the stimulus.
52. Synaesthesia
– Synaesthesia is the experience of a stimulus in one sense
modality producing a sensory experience in another.
– For example,
• the feeling of cold in one’s spine on hearing a fingernail
scratch a blackboard.
• hallucinogenic drugs such as LSD or mescaline when
the subject might describe feeling, tasting and hearing
flowers simultaneously.
53. Reflex hallucinations
– It is a morbid form of synaesthesia. In a reflex hallucination
a stimulus in one sensory field produces a hallucination in
another.
• For example, a patient felt a pain in her head (somatic
hallucination) when she heard other people sneeze
(the stimulus) and was convinced that sneezing caused
the pain.
54. Extracampine hallucinations
– 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 .
• hear voices talking in London when they are in
Liverpool.
– These hallucinations can occur in
• healthy people as hypnagogic hallucinations
• schizophrenia
• organic conditions, including epilepsy.
55. Autoscopy or phantom mirror-image
– Autoscopy, also called phantom mirror-image, is the
experience of seeing oneself and knowing that it is
oneself.
– Healthy >emotionally upset or exhausted.
– Acute and sub-acute delirious states, occasionally patients
with schizophrenia.
– Epilepsy, focal lesions affecting the parieto−occipital
region and toxic infective states.
– A few patients suffering from organic states look in the
mirror and see no image, known as negative Autoscopy.
56. Hypnagogic and hypnopompic
hallucinations
– When the subject is falling asleep or waking up respectively.
– Hypnopompic should be reserved for those hallucinatory experiences
that persist from sleep when the eyes are open.
– 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,e.g.Deprived of sleep .
– Not indicative of any psychopathology
– Also occur in narcolepsy.
57. Organic hallucinations
– Any sensory modality .
– Eye disorders ,central nervous system ,lesions of the optic tract.
– Charles bonnet syndrome.
– Dementias as well as delirium and substance abuse >visual
hallucinations.
– The phantom limb is the most common organic somatic hallucination
of psychiatric origin. ( Only >6yr age)
• Equivalent perceptions of phantom organs may also occur after
other surgical procedures such as mastectomy, enucleation of the
eye, removal of the larynx
– Lesions of the parietal lobe >somatic hallucinations with distortion or
splitting-off of body parts.
– Lesions of the temporal lobe > complex scenic hallucinations ,multi-
sensory hallucinations but they do not include somatic hallucinations.
58. The patient’s attitude to hallucinations
• Organic hallucinations >Terrified by the visual hallucinations and
desperately to get away from them.
• Persecuted attitude and the visual hallucinations
↓
Resistance to all nursing care & impulsive attempts to escape
• Lilliputian hallucinations> Amusement (not terrify) by the patient and may
be watched with delight.
• Patients with depression>Instructions to kill themselves are not
frightening since they may have thought of this for some time anyway.
• Schizophrenia:
– Acute schizophrenia >Very frightening >Attack the person he believes
to be their source.
– Chronic schizophrenia >Not troubled >Treat them as old friends.
59. Body image distortions
Hyperschemazia
• Magnification of body parts.
– When part of the body is painful it may feel larger than normal.
– Partial paralysis >affected segment feels heavy and large, as in
• Brown–sequard paralysis.
• Peripheral vascular disease
• Multiple sclerosis
• Thrombosis of the posterior inferior cerebellar artery.
– It may also occur in non-organic conditions such as
• Hypochondriasis,
• Depersonalisation
• Conversions disorder,
• Feelings of fatness in anorexia nervosa
60. Aschemazia or hyposchemazia
• Perception of body parts as absent or diminished
– Parietal lobe lesions such as in thrombosis of the right middle cerebral
artery.
– Following transaction of the spinal cord.
– Health volunteers when underwater.
• Hyposchemazia must be distinguished from nihilistic delusions.
61. Paraschemazia
• Parts of the body are distorted or twisted or separated from the rest of
the body
– Hallucinogenic use
– Epileptic aura
– Migraine on rare occasions.
62. Hemi somatognosia
• Unilateral lack of body image in which the person behaves as
if one side of the body is missing .
• migraine or during an epileptic aura.
63. Anosognosia
• Denial of illness.
• Patient denied their hemiplegia early after stroke and
refused to admit to any weakness despite demonstration that
it is paralysed.
64. Hemispatial neglect
• Neglect of the hemispace on the contralateral side to the
lesion when performing tasks.
• Gerstmann syndrome (lesion of dominant parietal lobe)
consists of agraphia, acalculia, finger agnosia and right/left
disorientation.
65. Conclusion
• Perceptual disturbances may be present in
normal individual.
• Merely hearing voices or seeing objects are
not hallucination.
• Proper knowledge of psychopathology will
help us to make true diagnosis.
66. References
• Fish’s clinical psychopathology.
• British journal of psychiatry.
• Sims' symptoms in the mind: an introduction
to descriptive psychopathology.
