Distortions in perception (Ch9) Flashcards
What does perceptual distortion involve?
An inconsistency or ‘mismatch’ between a perceptual experience and physical reality.
What is a visual illusion?
A perception of visual stimulus in a way that conflicts with how it is in physical reality.
What do visual illusions prove?
That the visual sensory system is prone to errors of judgement and perceptual distortions.
What is the Müller-Lyer illusion?
Visual illusion where two lines of equal lengh have ‘feather tail’ and ‘arrowhead’, and are incorrectly percieved as different lengths
Why is the Müller-Lyer illusion perceived incorrectly?
- perceptual error using inappropriate mental strategies (e,g wrong depth cues)
- contradicts what we have learnt in life about physical reality.
(cannot make sense of illusion, even after explanation)
Müller-Lyer illusion
What is the carpentered world hypothesis?
Illusion occurs due to similarity to familiar architectural features in 3D world we experience in everyday life
In everyday life, used to seeing corners and using them judge distances
What is the Ames room illusion?
Involves people appearing smaller or larger, depending on where they are standing.
Why does the ames illusion work?
Based on unusual construct of room, particularly back wall,
- Involves trapezium shaped room that is longer and higher on one side than another
- When viewed with one eye, room seems rectangular
What is the apparent distance theory?
When two retinal images are the same size, but one image appears further away, further away image interpreted as bigger.
What are other distortions?
Agnosia and synaesthesisa.
What is agnosia?
Neurological disorder characterised by inability to recognise and identify objects or persons using one or more senses.
What is agnosia characterised by?
Loss or impairment of ability to recognise and identify objects, people, sounds or other sensory stimuli using one or more of the senses, despite otherwise normally functioning senses.
What is visual agnosia?
Loss or impairment of ability to recognise visual stimuli.
Can have difficulty recognising familiar objects and faces.
What is the cause of agnosia?
- Rare disorder caused by brain damage (<1%)
- Can occur suddenly due to stroke, traumatic brain injury
- gradually due to brain tumor, dementia, etc
What are the symptoms and treatment of agnosia?
- Depends on specific location of damage, extent and severity.
- No direct cure, underlying cause treated if found and where possible
- Rehabilitation - compensatory uses of other senses
