Chapter 5 - Influences on Visual Perception Flashcards
What are the main factors that influence visual perception?
Physiology
Aging
Genetics
Physiology influence on visual perception
If any components are damaged, deteriorates or is negatively impacted, the ability to visually perceive the world is compromised.
- Colour-blindness/deficient
Inability to distinguish between certain colours due to impaired or missing cones
- Achloropsia
Perceive only black and white
Lack of cone vision, but also neural pathway damage
Aging examples of influence on visual perception
- Presbyopia
- Floaters
- Cataracts
- Age related macular degeneration
- Glaucoma
Examples of genetic influence on visual perception
- Inherited visual disorders
- Congenital visual disorders
- Colour vision deficiency
- Retinas pigmentosa
Presbyopia
Loss of lens flexibility – the lens stretches
Loss of lens ‘bend-ability’ hence losing ‘focus-ability’
Irreversible
Floaters
Tiny gel-like clumps of matter that float in the vitreous fluid surrounding the eyes
Starts in mid-40’s
Caused by deterioration of vitreous humor – little crystals form
Cataracts
Break down of proteins leads to the formation of a cloudy lens
Causes blurred vision & difficulty seeing at night or in bright light
Protein breakdown is seen as a natural part of aging
Fixed by surgery and interocular lens implant
Age related macular degeneration
Caused by deterioration & build up of grainy deposits in the macula
Inflammation & degeneration of the macula’s photoreceptor cells cause a blur spot in the centre of vision leading to a loss of detail
Glaucoma
Optic nerve is damaged due to increased pressure in the eye (aqueous hum)
Results in loss of peripheral vision
Examples of inherited visual disorders
Strabismus (cross eyed)
Amblyopia (the brain favours the other eye)
Astigmatism (the front surface of the eye is curved differently in one direction to the other)
Glaucoma
AMD (a blur spot in the centre of vision)
What is Congenital visual disorders?
A disorder present at birth from genetic factors or arise during gestation
Colour deficiency
More common in males, mutation of a gene on the X chromosome
Retinas Pigmentosa
A degenerative disease - gradual loss of peripheral vision (tunnel)
Examples of psychological influences
Past experiences
Context
Motivation
Emotion
What is Perceptual Constancies?
the tendency to maintain a stable perception of a stimulus, although the properties of the image on the retina may change
Size Constancy + Shape Constancy
Shape and size of the retinal image (reception, transduction, transmission) can change but it doesn’t change our perception (selection, organization, interpretation)
The Gestalt Principals
- Figure-ground organisation
- Camouflage
- Closure
- Similarity
- Proximity
types of depth perception
Binocular and Monocular
Depth Perception
The ability to accurately judge 3D space and distance by using cues in the environment
Perceptual set
perceiving things in a certain way due to past experience, context, or emotional state
Social influences on perception?
Cultural Skills; study by Hudson and Deregowski
