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.
gregory’s constructivist theory - evaluation points
support from research in different cultures - people interpret visual cues differently (e.g. Hudson’s study), showing experience affects perception
visual illusions - Gregory’s research used 2D visual illusions which are artificial, so theory may not apply to the real world
how does perception get going? - babies have some perceptual abilities (Fantz) so perception can’t just be the result of upbringing
factors affecting perception
culture, emotion, motivation, and expectation
factors affecting perception - culture
social world we live in (culture) affects what our senses pick up
hudson’s study - aim
to find out whether different cultures percieve depth cues in 2D images differently
hudson’s study - method
showed 2D drawings to black and white children, schooled and unschooled. children were asked which is nearer the man, the elephant or the antelope?
hudson’s study - results
black and white schooled participants more likely to percieve depth than unschooled participants. white schooled participants more likely to percieve depth than black schooled participants
hudson’s study - conclusion
different cultures use depth cues differently, so have different perceptual sets
hudson’s study - evaluation points
cross-cultural research - language differences could have made method used unclear, so validity is affected
problems with the method - the way the pictures were represented on paper may have confused participants, affecting findings
poor design - early cross-cultural studies were poorly designed (no control group), causing findings to lack validity
factors affecting perception - emotion
the tendency for our brain to notice exciting things and block threatening things
mcginnies’ study - aim
to know if anxiety-provoking things are noticed more than neutral things
mcginnies’ study - method
students shown neutral and ‘taboo’ words. had to say word out loud. emotional arousal measured through GSR.
mcginnies’ study - results
took longer to say taboo words. taboo words gave bigger change in GSR
mcginnies’ study - conclusion
emotion affects perceptual set, in this case perceptual defence
mcginnies’ study - evaluation points
objective measurement - GSR is a scientific method to measure emotion, better than rating scales
embarrassment not defence - delayed recognition may just be embarrassment not perceptual defence
results are contradictory - it’s difficult to draw conclusions from research that is inconsistent
factors affecting perception - motivation
wanting something increases its attractiveness
gilchrist and nesberg’s study - aim
to find out if food deprivation affects the perception of food
gilchrist and nesberg’s study - method
hungry (no food for 20 hours) and not hungry participants shown a slide of a meal
participants had to adjust light to level of slide shown
gilchrist and nesberg’s study - results
percieved food as brighter the longer deprived of food
gilchrist and nesberg’s study - conclusion
sensitivity greater when food deprived
hunger is a motivating factor that affects the perception of food
gilchrist and nesberg’s study - evaluation points
support from similar studies - sanford’s study found similar results which strengthens the validity of the conclusions
ethical issues - depriving people of food causes discomfort, a case of physical harm
not like everyday life - participants judged pictures rather than real food so it may not apply to the real world
factors affecting perception - expectation
beliefs based on past experiences can affect how much we attend to things
bruner and minturn’s study - aim
to find out if an ambiguous figure is seen differently if context is changed
bruner and minturn’s study - method
participants shown a sequence of letters or numbers with an ambiguous figure in the middle
bruner and minturn’s study - results
those who saw letters said B
those who saw numbers said 13
bruner and minturn’s study - conclusion
shows expectation is affected by the context the figure is presented
bruner and minturn’s study - evaluation points
artificial task - ambiguous figures are designed to trick perception, so task lacks validity
independent groups design - participant variables may have caused the difference in results not expectation
real-world application - the study can explain the sometimes serious mistakes people make in the real world
