perception (8)
sensation
the information recieved through our senses: they are processed by sense receptors such as our 5 senses
perception
how we organise and interpret the sensory information we recieve from our environment
fiction illusion
when an object colour or movement is percieved but the construction is not actually there - your mind adds something that doesnt exist
ambiguity illusion
an illusion where there is more than one possible way to interpret the image. the image is real but can be seen in multiple ways
monocular depth cue
perceptual cues that can be detected with one eye about distance and depth . if one eye was covered these would still be seen
binocular depth cue
perceptual cues that must be detected using both eyes about distance and depth
Necker cube
ambiguous
can be interpreted in 2 ways - percieved as pointing upwards to the right or downwards to the left
Rubin's vase
ambiguous
can be interpreted in 2 ways: 2 white faces or one black vase
Kanizsa triangle
fiction
when an object coulour or movement is percieved but the construction isnt actually there- a white triangle is percieved but isnt actually there
ponzo illusion
misinterpreted depth cues of size constancy and linnear perspective cause you to think the above line is longer than the one below, this is because the converging lines give the impression of distance therefore we judge the top line to be further away, however they are the same size
muller-lyer illusion
misinterpreted depth cue causes you to think the line with the inward facing arrowheads is longer than the one with the outward facing arrowheads
what are the monocular depth cues
height in plane
relative size
occlusion
linear perspective
what are the binocular depth cues
retinal disparity
convergence
height in plane
something that appears higher in the plane of vision is further away
relative size
larger objects in a visual field appear closer than smaller objects
occlusion
when something is covered partly by sometjing else in the plane of vision it is further away (than the thing covering it)
linear perspective
when parallel lines appear to converge the further away they are
retinal disparity
the disparity between what your left and right eyes see is greater the closer an object is
convergence
the closer an image/object is the more the eye muscles have to work to focus on the image as the eyes have to come together
Gibson's direct theory of perception
the NATURE interpretation of perception
perception happens directly & perceptual abilities are innate
sensation=perception
the visual environment gives all neccesary info needed by our brain to percieve accurately (sensory info, light,texture,detail)
we do not need to fill the gaps using expectation and past experience
weakness of gibson's direct theory
p- cant explain visual illusions
e- suggests we have all the info to percieve correctly therefore cant explain visual illusions
a- for example the ponzo illusion, we percieve the top line to be longer than the bottom line when that is not the case, showing that we arent given all the visual info to percieve correctly, meaning this is an incomplete theory
motion parallax
this is used to make judgements about movement. objects that are far away appear to move slowly as we move, in comparison to the objects closer to us (eg looking out of a car window, the sign you drove past appeared to 'move' out of your vision quite quickly whereas the mountains are 'moving' slower. ofc theyre not moving but you are)
gregory's constructivist theory
the NURTURE interpretation of perception
perception is an active process where the brain constructs what we see
perception is all to do with past experiences
sensory imput can be ambiguous or incomplete, this leads our brain to make a hypothesis about what were seeing
this is usually accurate however can lead to visual illusions when the brain's expectations are wrong
strength of gibsons direct theory
p- research support
e- visual cliff experiment: babied didnt wanna go off the "cliff", showing depth can be percieved instinctively without needing past experiences
a- shows that perception is innate, adds validity to the theory
visual cliff experiment
- to investigate wether depth perception is innate or learned
- 36 babies 6-14 months old placed on a "visual cliff" with a shallow and deep end covered in a pane of glass so there wasnt an actual drop and the babies werent at risk
a caregiver stood on the shallow end and encouraged the baby to come to them, then the same caregiver stood at the deep end and encouraged the baby to come to then
- a caregiver stood on the shallow end and all babies went to them without hesitation, whereas when the same caregiver stood on the deep end none of the babies crossed over to them
- depth perception appears to be innate as babies avoided the drop without needing prior experience
strength of gregory's constructivist theory
p- the theory is supported by evidence from visual illusions
e- for example illusions such as the muller lyer illusion occur due to past experiences and assumptions about depth and size
a- supports gregory's idea that perception is based on previous experiences and hypothesis testing, increasing the validity of the theory
weakness if gregory's constructivist theory
p- overemphasises the role of past experiences and underestimates the role of innate factors
e- studies such as the visual cliff study show that even young babies can percieve depth
a- suggests perception is at least partly innate, reducing the validity of gregory's theory
perceptual set
the tendency of the brain to notice or prefer certain aspects of the sensory environment. expectation affects perceptual set because you are more likely to notice or attend to certain stimuli because you are anticipating them
Bruner & Minturn study outline
a- to investigate wether expectation is an important factor in perceptual set- to see if you anticipate an object you are more likely to see that object
m- independent groups design
ppts shown a sequence of either numbers or letters
they were then asked to identify an ambiguous figure which could be interpreted as number or letter (13 ir B)
r- ppts who were given letters were more likely to identify b whereas ppts who were given nunbers were more likely to identify 13
c- expectation does affect perceptual set : by changing the context visual info is presented in it is possible to change the way it is percieved
bruner&minturn study evaluation (2xpea)
p- weakness- independent groups
e- participant variables
a- lowers internal validity
p- weakness- artificial task
e- doesnt happen day2day, lacks mundane realism
a- lowers ecological validity