Flashcards in PSY - Visual Perception Deck (51):
What is perception?
Process by which we give meaning to sensory information, resulting in personal interpretation
What is the order of light travel through the physiological features of the eye?
Cornea > Aqueous Humour > Pupil (Iris) > Lens (Ciliary Muscles) > Vitreous Humour > Retina > Optic Nerve > Visual Cortex
What is the cornea? What does it do?
A transparent, convex-shaped covering
Protects the eye, helps focus light rays onto the back of the retina
What is the aqueous humour? What does it do?
Between the cornea and the lens, it is a watery fluid
Helps maintain the shape of the eyeball and provide nutrients & oxygen to the eye, as well as carrying away waste products
What is the pupil? What does it do?
Not a structure in itself, opening in the iris
Controls amount of light entering the eye (dilates in dim, contracts in light)
What is the iris? What does it do?
Coloured, ring of muscles
Expand and contract to change size of pupil
What is the lens? What does it do?
Transparent, flexible, convex, behind pupil
Focuses light onto retina, (bulge for nearby, flatten for distant), controlled by ciliary muscles
What is the vitreous humour? What does it do?
Helps maintain shape of eyeball, helps focus light
What is the retina? What does it do?
Consists of several layers of nerve tissue and light-sensitive visual receptor cells (photoreceptors)
Receives and absorbs light, processes images, connected to brain via optic nerve, image focussed on retina is inverted and reversed
What happens in reception?
Eye receives light from external environment and focuses it onto retina where image of stimulus is captured, detected by photoreceptors
What are the characteristics of rods?
Photoreceptor, low light, night vision, poor at detecting details, not colour, 125 million
What are the characteristics of cones?
Photoreceptor, high light, well-lit vision, good at detecting detail, colour vision, 6.5 million
What happens in transduction?
Photoreceptors change electromagnetic energy (light) into electrical impulses (signals) which can travel along optic nerve to brain
What happens in transmission?
Sending electrical impulses along optic nerve to brain (visual cortex, which specialises in receiving and processing visual information, but sends information to other areas for further processing
What happens in selection?
Feature detector cells filter and select important pieces of visual information (eg. lines, dots, circles etc.)
What happens in organisation?
Arranging visual information features in meaningful way, with visual perception principles (eg. Gestalt principles), automatic
What happens in interpretation?
Process of assigning meaning to visual information
Psychological processes: past experience with object, gestalt principles, context
Physiological processes: visual information sent to other brain areas to decipher WHERE and WHAT an object is
What is the stroop effect? Why does this occur?
Word colour different to actual colour
Brain has difficulty processing conflicting pieces of information, automatic response is to first read the word
How does the biological perspective explain visual perception?
Physiology of eye, neural events
How does the behavioural perspective explain visual perception?
Learning, past experience, rewards/punishments, expectations
How does the socio-cultural perspective explain visual perception?
Personal circumstances, experiences within culture
How does the cognitive perspective explain visual perception?
How we acquire and process visual information, systems controlled by brain
What are the Gestalt principles?
Group features to perceive complete form, may only be for those who studied geometric concepts formally(Luria)/had exp. with 2D shapes
What is figure-ground organisation?
Figure stands out from ground (surroundings), separated by figure's contour, eg signs, illusions ('reversible figures')
What is closure?
Closure: close up gaps mentally in image > perception of whole (eg. logos)
What is similarity?
Perceive similar featured parts as whole/together (eg uniforms, Ishihara colour blindness tests)
What is proximity?
Aka Nearness: parts located together perceived as together (eg letters = words, musical notes = melody)
What are the binocular depth cues?
What is convergence?
Changes in tension in eye muscles determine distance (turn inwards for close objects), useful around 6 metres because here lines of sight of both eyes is basically parallel
What is retinal disparity?
Eyes are about 6-7 cm apart, so different image (about less than 9-10 m away) cast on each retina, and different location of visual images on retinae are compared/fused to make depth judgments
What are the monocular depth cues?
* Linear Perspective
* Texture Gradient
* Relative Size
* Height in the Visual Field
*= pictorial cues b/c used in artworks
What is accommodation?
Automatic adjustment of lens shape to focus an object in response to depth (bulge for close, flatten for distant) - extent to which changes shape gives info r.e. distance
What is linear perspective?
Apparent convergence of parallel lines as they recede into distance
What is interposition?
Aka overlap, is when one object partially covers another (blocked = further away)
What is texture gradient?
Gradual reduction of detail that occurs in a surface as it recedes into distance (close = finer detail)
What is relative size?
Tendency to visually perceive object that produces largest image on retina as being closer and vice versa (expected to be same size in real life)
What is Height in the Visual Field?
Location of objects in our field of vision, whereby objects close to horizon are perceived as more distant
What are the perceptual constancies?
Tendency to perceive object as unchanging/stable despite changes occur to image cast on retina
What is size constancy?
Object's actual size remains same despite size cast on retina changing (past experience = vital)
What is shape constancy?
Tendency to perceive object as maintaining shape despite change to shape of image cast on retina
What is brightness constancy?
Tendency to perceive object as maintaining brightness level in relation to surroundings despite changes in amount of light being reflected from object to retina
What is perceptual set?
Predisposition to perceive something in accordance with what we expect it to be, aka expectancy, can quicken reactions/understanding, can also make us miss relevant things we don't expect
How does context influence perceptual set?
= Setting in which perception is made
Relevant aspects of setting focused on (> quick & accurate interpretation), can > slower & inaccurate interpretations
Eg. Bruner and Minturn (1955): B and 13
How does motivation influence perceptual set?
Processes which activate behaviour which is directed towards achieving a particular goal
Psych (interests) and Physio factors (needs)
How does emotional state influence perceptual set?
Set us to perceive info in way consistent with that emotion
Eg. Coat hanger in dark > scared/frightened
How does past experience influence perceptual set?
Predispose us to perceive info in personal way b/c of personal exp. > individual differences in how perceived
Eg. Toch and Schulte (1961): 'binocular rivalry' (two images spontaneously presented, one to each eye - usually one actually seen) > violent and non violent situations for police trainees/officers and not
How do cultural factors influence perceptual set?
Experience with/in particular culture influences way we process and interpret visual info
Eg. Malawi people with dog photos could not identify dog b/c culture not accustomed to photos / 2D images of 3D things
What are visual illusions?
Misinterpretation of real sensory info (mismatch perception and reality)
Explain the Muller-Lyer illusion.
Line with feather tail is perceived as longer than longer than line with arrowhead
Biological: eye movements & brain's failure to properly process different info about eye movements (FT requires longer eye movements & also it takes more eye movements to view line w/ inward arrows) - rejected b/c still seen even with no eye movement
Behavioural: because it contradicts what learned about physical reality, 'carpentered world hypothesis' (illusion occurs b/c of its similarity to familiar architectural features in 3D real world = corners, FT > further away > longer
Socio-Cultural: 'non-carpentered world' people (Zulus w/ circle huts > less exposed and thus less likely to perceive illusion), race/education/training also proposed as relevant
Cognitive: may be due to inappropriate mental strategies (eg assuming smaller line is further away than it is = size constancy & depth cues), rejected as other shapes work as well as FT and AH
Explain the moon illusion.
Apparent distance theory: sky background > no depth cues > underestimate size, whereas tree/building background > further away > larger than zenith