Disorders of perception

Question 1

Perceptual distortions

Answer 1

-stimulus is present, the object is perceived but the quality of the object is altered

Question 2

Illusions

Answer 2

-stimulus is present but something else is perceived

Question 3

Hallucinations

Answer 3

• stimulus absent

- perception without stimulus

Question 4

Negative hallucinations

Answer 4

-stimulus is present but no object is perceived

Question 5

Perceptual distortion

Answer 5

-stimulus is perceived as corresponding object but not accurately- changes in shape, colour etc

Question 6

Change in shape of object

Answer 6

-dysmegalopsia

Question 7

Change in size of an object

Answer 7

• micropsia

- macropsia

Question 8

Eidetic imagery

Answer 8

• special ability of memory where visual images are drawn from memory accurately at will and described as being perceived current;y
• notes in 2-15% school goers
• may be part of religious experiences
• no pathology

Question 9

Affect illusion

Answer 9

• prevailing emotional state leads to misconceptions
• often fearful, emotion provoking
• disappears on focussing the object with extra concentration
• e.g a depressed patient reading ‘deed’ as ‘dead’

Question 10

Pareidolic illusion

Answer 10

• formed objects from ambiguous stimuli, coloured by prevailing emotion
• often playful and whimsical
• on paying extra attention the object intensifies
• e.g seeing cars in the cloud
• using psychodelics or delirium

Question 11

Completion illusion

Answer 11

• stimulus that does not form a complete object might be perceived to be complete
• due to inattention
• disappearance on concentration is the rule
• CCOK is read as COOK

Question 12

Elementary auditory hallucination

Answer 12

• unstructurede hallucinations

- seen in acute organic states

Question 13

Musical hallucinations

Answer 13

• similar to Charles Bonnet Syndrome

- can occur in those with deafness

Question 14

Lilliputian hallucinations

Answer 14

• seen in DTs

- tiny people, insects

Question 15

Autoscopic hallucinations

Answer 15

• see oneself
• in depression
• phantom mirror images
• in negative autoscopy one looks into a mirror and sees no image at all

Question 16

Palinopsia

Answer 16

• ‘again’ ‘seeing’
• visual disturbance causes images to persist even after their corresponding stimulus has left
• seen in LSD use, migraine, occipital epilepsy, head trauma

Question 17

Coenesthetic hallucinations

Answer 17

• visceral hallucinations -pain deep in viscera
• suggest schizophrenia
• also seen in ETOH and benzo withdrawal

Question 18

Formication

Answer 18

• from formic acid in ants
• special type of haptic hallucination
• unpleasant sensation of little animals or insects crawling on skin
• seeen in DTs and cocaine
• also seen in parietal seizures

Question 19

Olfactory hallucinations

Answer 19

• can occur in the aura of TLE

- in depression it can be associated with nialism

Question 20

Gustatory hallucinations

Answer 20

• bitter taste of poison can give rise to delusions of persecution in schizophrenia
• also seen in TLE

Question 21

Extracampine hallucinations

Answer 21

• hallucinations outside the normal FIELD of perception
• e.g images behind your back, voices from Scotland
• occur in schizophrenia, epilesy and hypnagogic hallucinations of healthy people

Question 22

Hypnagogic hallucinations

Answer 22

• when you are GOING to sleep
• 3x more common than hypnapompic
• 37% adults experience at least once
• more specific for narcolepsy
• EEG shows alpha rhythm
• hearing one’s name is most common

Question 23

Hypnapompic hallucinations

Answer 23

-when you are waking up

Question 24

Functional hallucinations

Answer 24

• external stimulus provokes hallucination
• voices heard whenever the noise of water running though the tap is heard
• same modality

Question 25

Reflex hallucinations

Answer 25

• similar to functional
• hallucination in one modality is provoked reflexively by a stimulus in another modality
• seeing an angel when listening to music

Question 26

Synaesthesia

Answer 26

• tasting music, hearing colours and smelling voices
• cross modality perception
• common in females 4:1 to 6:1
• runs in families
• colour-number synaesthesia is the most common form
• can be acquired in neurological disease
• can be induced by ingesting mescaline