Visual Perception 5 Flashcards
what is compromised in the theory of the conflicting cues
size perception
the converging lines give the perception of depth in a 2D image and the visual system assumes that a retinal image that appears to be further away will have a bigger physical size
the ponzo illusion
-tells us that this object must be more distant, same retinal size but appears more distant so it tell us that it must be bigger
what is the ames illusion
how is the visual angle related
what does the visual system assume
back wall shift and one person is closwer and one is more distance giving them a diff in size
both poeple have same visual angle
visual system assumes that the 2 poeple are at the same distance so one person appears larger and there is a greater visual angle
what are the 2 explainations for the Ames room
- size-dist scaling equation
2. relative size
what is the size-dist scaling equation explaination for the Ames room
the construction of the ames room cuases the person on the left to have a much smaller visual angle than the person on the right
-we perceive this distance as being the same bc of size-dist equation even though its not => 2 diff retinal img sizes => perception of size is diff
D is the same and R is diff and S is diff
what is relative size explaination for the Ames room
person on the right fills the whole room
bc we know that a normal size person wouldn’t fill the whole room so we perceive them as bigger
what is the moon illusion
the physicla size and dist of moon stays the same throughout the night => retinal image remians the same
- what chagnes is the perceived dist of the moon
- when the moon is closer to the horizon it is perceived as being further waway than when its a zenith (highest point reached)
why does the moon appear to be further away when its on the horizon
why does it appear to be shorter when its at zenith
bc we have depth info and we can judge the dist
at zenith we have no cues for depth and therefore we misperceive the dist as being shorter (bigger moon()
S=a(RxD)
what is the angular size contrast theory for the moon illusion
moon appears smaller when its high on the sky bc it is surrounded by a very big object (black sky)
what is the ebbinghaus illusion
circle surrounded by large circles look bigger bc of relative size
which illusions do not rely on prior knowledge but on physiology alone
- the hermann grid illusion
- mach bands
- simultaneous contrast
what is the hermann grid illusion
you see dark circles appearing at the intersections
- explained by lateral inhibition (influence of neurons on surrounding neurons)
ex. center-surround receptive field=inhibition - more inhibitions when looking at the intersections than when not
why don’t we see the reduction of lateral inhibition when we fixate at an intersection
prob cuase the bipolar cell receptive filed size is small enough so it doesn’t receive strong inhibitroy input from many surrouding neurons
what is the scintillating grid illusion
a bright spot appears darker at an intersection when you move your eyes around it
lateral inhibition
what are mach bands
stripes of dark and light created at the border of a dark and light surface
-appear as light enhancements at the light side of the border and dark at the dark side of the border
