Perception Flashcards
(64 cards)
What type of theory is Gregory’s?
Top-down theory of perception
What type of theory is Gibson’s?
Bottom-up direct theory of perception
Primary cues in perception
Not dependent on experience
Work on the fact we have binocular vision
- Convergence
- Retinal disparity
- Accommodation (only monocular cue)
Convergence
Primary cue
Work on the fact we have binocular vision
Muscles of eye contract and pull eyes inwards when we focus on a item near to us
Retinal disparity
Primary cue
Work on the fact we have binocular vision
Eyes are about 6cm apart so receive slightly different information
Brain combines two images in a process called stereopsis
Uses this new stereoptic image to judge depth - greater disparity of image between eyes, closer it is
Stereopsis
Process that combines the images received from each eye into a single stereoptic image
Accommodation
Only monocular primary cue
Lens change shape depending on whether the viewed object is nearby or far away
Secondary cues in perception
Most of the monocular cues classed as secondary cues
Depend on learning and experience
One example is texture gradient
Gibson and Walk
Visual cliff experiment - black and white checked material
36 infants, 6-14 months old
Found that infants wouldn’t cross the ‘drop’ to mothers
If they toppled over near the edge they showed a fear reaction
Concluded that infants had an innate awareness of depth
Gibson’s theory of perception
Bottom-up direct
Believed that information from the eyes lead directly to perception
Perception is innate
Gregory’s theory of perception
Top-down
Constructivist
Perception is based on learning and schemas
Unconscious process
We hypothesise about what we see
Hudson
Showed a 2D image of a man (foreground) pointing a spear at a antelope (foreground) with a elephant in the gap between them in the background to different African cultures
When asked what the man was pointing his spear at they said the elephant
Didn’t’ understand depth cues like overlap that we use in Western culture to perceive depth in photos
Optic array (Gibson)
The structure of light in the environment
Movement (Gibson)
Even when body is still, eyes keep moving
This gives you lots of visual information about positions of objects and surfacesrather than what you would get without movement
Calls the way light structure changes as you move the ambient optic array
Invariant information (Gibson)
Used to gauge distance, depth and orientation of objects
Some features of the ambient optic array invariant and don’t change:
- Horizon ratio
- Optic flow patterns
- Texture gradient
Texture gradient (Gibson)
Elements of object coarse and far apart - close to observer
Elements of object smooth and close together - far from observer
Optic flow patterns (Gibson)
Created as elements in the environment pass around us
Gibson thought whole visual field was more important than individual objects
Provided information of speed, direction and altitude to pilots in Gibson’s study
Horizon ratio (Gibson)
Extent of which an object is above horizon compared with extent it is below 2 objects of the same hight on a flat surface will have the same horizon ratio
Doesn’t change with distance from observer
Affordances (Gibson)
We automatically know the use of an object when we see it
So a tribesman from a forest theoretically should know how to use a pen from first glance
Main elements of Gibson’s theory of perception
Optic array
Movement
Invariant information
Affordances
AO2 for Gibson’s theory
Gibson and Walk
Hudson (against)
Gibson’s study into WWII pilots
AO2 for Gregory’s theory
Müller-Lyre illusion
Duck/rabbit illusion
Hudson
Johanson (lights)
Diener (APT/aPt)
Johanson
Participants watched film
Man with flashing lights attached to major joints on body in a darkened room
Couldn’t tell what he was until he started moving
Required schema of how people move to tell what the lights were attached to
Diener
Misplaced size constancy
Pair of letters (APt and aPt)
Participants perceived the second ‘P’ as lower-case and smaller
