3. Perception
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, context,
prior experiences, memory, and, most
importantly, prior concepts.
‘We are not given the world: we make our world
through incessant experience, categorization,
memory, reconnection’ (Sachs 1995)
It is therefore the case that perception that is not a
passive process but an active one that involves
the construction of an external world that
depends on internal templates.
4. Characteristics of Perception
Are of concrete reality
Occur in external objective space
Clearly delineated
Sensory elements are full and fresh
Constant and remain unaltered
Independent of our will
(Jaspers, 1962)
6. • Imagery is the internal mental representation of the world
and is actively drawn from memory.
• In day-to-day life, it is common to refer to ‘seeing in the
mind’s eyes’ or ‘hearing in the mind’s ears’.
Imagery
7. • Images are figurative and have a character of subjectivity
• They appear in the inner subjective space
• They are not clearly delineated and come before us incomplete
• Although sensory elements are individually equal of those in
perception, mostly they are insufficient
• Images dissipate and always have to be recreated
• Images are actively created and are dependent on our will.
Characteristics Of Imagery
8. Applied aspect of Imagery
Vivid sensory description to create mental pictures.
In Psychopathology: an understanding of the nature of
imagery is required for examining the nature of perceptions,
hallucinations and pseudohallucinations.
The sun was shining brightly in the sky.
The bright yellow sun beamed down my shoulders, wrapping me
in a blanket of sunshine.
9. Normal Perception Imagery
Stimulus present Stimulus absent
External and objective space Internal and subjective space
Clearly delineated Incomplete and poorly delineated
Sensory elements are full and fresh Sensory elements incomplete
constant Not constant have to be recreated
Independent of will Dependent on the will
10. Synesthesia
Perception of an object, presented in one sensory
modality at the same time as in different sensory
modality.
“I don’t know what the color green looks like. But I
know what green tastes like!” –Taria Camerino
11. Synesthesia continued..
Various forms:
grapheme to color; time unit to color; musical sounds
to color; general sounds to color; and, phoneme to
color.
sounds to taste, sound to touch;
vision to taste
spatially extended, but different from seeing or
imagining
Experience close to the body and within ‘peri-
personal space’
Consistent over time
Elementary and specific in nature
12. One of the things I love about my husband are the colours of
his voice and his laugh. It’s a wonderful golden brown, like
crisp, buttery toast, which sounds very odd, I know , but it is
very real. (Cytowic and Eagleman, 2009)
13. Abnormal Perception
Sensory Distortion
Real perceptual object
which is perceived in a
distorted way
Sensory Deception
(false perceptions)
New perception that
may occur that may or
may not be in response
to external stimuli
14. • Distortion: The act of twisting or altering something out of
its true, natural, or original state..
• Sensory Distortion: Real perceptual object which is
perceived in a distorted way.
• Disturbance of the mental state, with or without organic
brain pathology, may cause sensory distortion.
Sensory Distortion
16. Distortion in Intensity
• Hyperesthesia (increased intensity of
sensations)
• Hyperacusis
• Causes:
• Lowering of physiological
threshold.
• Intense emotions
• Experienced in:
• Anxiety
• Depressive disorder,
• Hangover from alcohol
• Migraine
• Hypochondriacal personalities
17. • Hypoesthesia (decreased intensity of
stimulus)
• Hypoacusis
• Causes:
• Increase of physiological
threshold.
• Decreased attention
• Experienced in
• Ageing
• Delirium
• Depression (lowered visual n
gustatory sensations)
• Attention deficit disorder
18. Quality Distortion
It is mainly visual perceptions brought about
by toxic substances.
Drug toxicity
Digitalis, Santonin: Xanthopsia
Mesacline: Chloropsia
Viagra: Erythropsia
Lithium: Metallic taste
Derealization
Everything looks unreal and
strange
Mania
Objects looks perfect and
beautiful
19. •Distortions in Spatial Form
• Refers to Change in the perceived shape
of an object
• Also known as “Dysmegalopsia”
• Alice In Wonderland Syndrome
(Todd’s Syndrome)
20. Distortions in Spatial Form
Micropsia
Seeing objects smaller than they really are or farther away than they really are.
Retinal disease and scarring
Accomodation and convergence disorder
Parietal and temporal lobe disorder
Papilledema
Schizophrenia
Macropsia or Megalopsia
Seeing objects larger than they really are
Complete paralysis of accommodation
Atropine/hyoscine poisoning
Hypoxia
Chronic arachidonitis
Temporal lobe epilepsy
22. Distortions in Spatial Form
Teleopsia: Object appearing far away
than it should.
Pelopsia: Object appearing nearer than
it should
can be caused by changes in atmospheric
clarity
sometimes by wearing a corrective lens
Porropsia: Experience of retreat of
subjects into the distance without any
change in size
23. Disorders of Experience of Time
Varieties of time:
Physical (Actual time)
Personal (Determined by
personal judgment of
passage of time)
Affected by psychiatric
disorders
24. Sensory Deception
DECEPTION: the act of causing someone to accept as true or valid what is
false or invalid.
SENSORY DECEPTION
Occurring of new perception that may or may not be in response to external
stimulus.
Altered perception of real objects to consider the perception of objects that
are not there and are new perceptions that include:-
26. Illusion
Latin /illusio/ which means to mock (fake).
Stimuli from a perceived object
Mental Image
Illusion False Perception
27. Illusion
Not indicative of Psychopathology by themselves
Examples:
Muller-Lyer illusion
Person in dark road can mistake a shadow as attacker
May occur in any sensory modality but visual modality is more
common
Delirium
Anxious and bewildered individuals
Schizophrenia
Psychomimetic drugs
31. Fantastic Illusion
Fantastic illusions in which patients saw
extraordinary modifications to their
environment
Most of the time attributed to exaggeration
and confabulation.
More common in the world of fiction than
in the psychiatric realm. (Hamilton 1974)
32. Illusion Vs Functional Hallucination
Functional hallucination, which occurs when a certain
percept is necessary for the production of a hallucination,
but the hallucination is not a transformation of that
perception.
33. Illusion
VS
Perceptual Misinterpretation
Making a mistake as to the nature of
perception without that perception
being particularly influenced by
emotion mixed with fantasy.
Rather it can be affected by previous
information.
34. Hallucination
Latin word /allucinari/
Meaning wander in mind and
intent to mislead
In English: Sir Thomas Browne
(1646)
In psychiatry: Esquirol (1817) : A
perception without object
35. Pseudohallucination
Pseudohallucination is a perceptual experience that is figurative, not
concretely real, and occurs in inner subjective space, not in external objective
space.
Subjective perceptions similar to hallucinations, with respect to their character
and vividness, but that differ from those because these do not have objective
reality. -Victor Kandinsky
Corelates to Imagery as hallucination relates to Perception.
36. Qualities of Pseudohallucination
Full Consciousness
Inner subjective space
Definite outlines
Constancy retained, insight preserved
Relevant to emotions, needs, and
actions
Depends on the observer for
existence
By Jasper 1962
37. • Its presence merely doesn’t determine the presence of any
psychopathology.
• But, can be experienced in:
• Obsessional
• Depressive
• Histrionic Personality
• Delirious
• Psychotomimetic Drug Users
Pseudohallucination and Psychiatry
38. The significance of hallucination is that it almost always denotes a
morbid mental state.
The significance of Pseudohallucination is in its differential diagnosis
from hallucination, as Pseudohallucination is not necessarily
psychopathological.
39. References
Fish’s Clinical Psychopathology, 4th Edition, Patricia Casey, Brendan Kelly
SIMS’ Symptoms in the Mind, 6th Edition, Femi Oyebode
these 2 cases underline the distincition btwn sensation n perception
3rd pg candidate working in ward
Vivid = Clear detailed
Illusions, hallucination and pseudo hallucinations will be included under false perception
The possibility of a neurologic deficit affecting perception also needs to be considered.
Eg: cricket ball like identify garcha but usko features haru like size,shape,color(much more bright in hyperesthesia,in mania n depression ma dull color)
The perceptual distortions of colour occurs in schizophrenia.
Pt who are hypomanic or with epileptic aura or under influence of lsd may see colours as very bright n intense
This highlights the importance of speaking to a delirious patient more loudly and more slowly than usual.
In depressed individual everything looks black and all food tastes same.
A neurological disorder where A set of symptms with alteration of body image where size of body parts or sizes of external objects are perceived incorrectly
The term micro n macropsia have also been used to describe the changes of size in images experienced in dreams n hallucination I,e in liliputian ma small nad BROBDINGNAGIAN HALLUCINATIONS ma giant dekhcha
Alloasthesia =perceived object is in different position frm wht is expected.
Porropsia=tada pni ani syano pni
Eg: in severe depression pt may feel that time passes very slowly.
Slowing down of time is most marked in pt with psychotic depressive symptms/
Where as manic pt feels time speeds by n that days r not long enough to do eveythng.
Some pt with temporal lobe lesions compalains thet time either passes slowly or quickly
Schizo pt abnormalites of time judgement,interval haru less cha bhncha.
In illusions stimuli frm perceived object are combined with mental iange to produce false perception
*Bcz they occur in absence of psy disorder
In which 2 lines of equal length can be made to appear unqual depending on the direction of the arrowheads
LSD n Cannabis
Pareidolia=vivid iilusions occur without the pt. making any effort, due to excessive fantasy thinking
Pt sees vivid pictures in in fir or in clouds without any effort or evn against his will
both of these occur in response to environment stimulus,but in a functinal hallucinationboth the stimulus n hallucinations r perceived by the pt simultaneously n can be identified as separate n not as transformation of the stimulus.
Bhitra bta choko jsto lagcha, baira bta hoina.bhitrai bta aawaz aucha
Normal perception ko counterpart is hallucination ani
Imagery ko pseudohallucination