Perception Flashcards
sensation
physical stimulation of the five senses processed by sense receptors
perception
the brain interpreting and organising the sensory information
sensation vs. perception
sensation is the detecion of a stimulus
perception is interpreting what it means
theories of perception
gregory sees a difference between sensation and perception. gibson does not.
visual cues and constancies
cues = information about movement, distance, etc.
constancies = seeing object as the same from different angles
binocular depth cues
retinal disparity - difference between the view of the left and right eye gives brain information sbout depth and distance
convergence - eyes point closer together when an object is close. muscles work harder so know distance and depth
monocular depth cues
height in plane - objects higher up appear further away
relative size - smaller objects appear further away
occlusion - if one object obscures part of another object, it is seen as closer
linear perspective - parallel lines appear closer as they become more distant
gibson’s direct theory of perception
perception doesn’t draw on past experience, in contrast with Gregory’s thory
gibson’s direct theory - key points
sufficient information for direct perception - sensation and perception are the same. the eyes detect everything we need without having to make inferences
optic flow patterns - when moving, things in the distance appear stationary and everything else rushes past. provides perceptual information about speed and distance
motion parallax - a monocular depth cue. when we are moving padt them, closer objects appear to move faster than objects that are further away. provides perceptual informatioj sbout speed and distance
the influence of nature - perception is inborn not learned
gibson’s direct theory - evaluation points
real-world meaning - research was on ww2 pilots, so relevant to daily life
theory struggles to explain visual illusions - perception is seen as accurate but illusions trick the brain, so theory is incomplete
support for the role of nature - Gibson and Walk showed few infants crawl off a visual cliff, so are born with depth perception
visual illusions
Ponzo illusion - misinterpreted depth cue. percieved horizontal line higher up as longer
Müller-Lyer illuion - misinterpreted depth cue. two vertical lines same length. line with outgoing fins seen as longer
Rubin’s vase - ambiguous figure. face and vase. both pictures correct, brain alternates.
Ames room - misinterpreted depth cue. room shape of a trapezoid. people seen as different sizes even though they are the same
size constancy
objects percieved as constant size despite size on retina changing with distance
misinterpreted depth cues
objects apparently in the distance scaled up by brain to look normal size, causes visual illusions
- ponzo illusion (converging lines gives illusion of distance, so you mentalling enlarge the top line.)
- Müller-Lyer illusion (ingoing fins: shape of outside building, appears closer, is scaled down. outgoing fins: inside corner of a room, appears further away, so scaled up)
ambiguous figures
two possible interpretations of an image; the brain can’t decide which is correct.
- Necker cube (cube can be seen as pointing upwards to the right or downwards to the left)
fiction
seeing something that is not there
- Kanizsa triangle (illusory contours create impression of a second triangle)
gibson’s constructivist theory of perception
contrasts with Gibson’s theory. proposes that sensation and perception are not the same.
gregory’s constructivist theory - key points
perception as a construction - brain uses incoming information and information we already know to form a hypothesis / guess
inference - brain fills in the gaps go create a conclusion about what is being seen
visual cues - visual illusions occur because of incorrect conclusions from visual cues
past experience (the role of nurture) - perception is learned from experience. the more we interact the more sophisticated our perception becomes.
