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Flashcards in Visual Perception 4 Deck (45)
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1
Q

points on the retina that overlap if the eyes are superimposed on each other

A

corresponding retinal points

2
Q

if we superimpose the 2 eyes then the two retinal images….

A

overlap

3
Q

what is a horopter

A

hypothetical surface

-objects that fall on the horopter create corresponding retinal points

4
Q

objects that don’t fall on the horopter create what

A

non-corresponding points

5
Q

the difference btwn the non-correspoding retinal points from the hypothetical corresponding points is called

A

disparity

6
Q

corresponding retinal points have ___ dispartity while noncorr points have ____ dispartiy

A

corr: 0

non-corr: greater than 0

7
Q

the horopter is a surface of ___ disparity and its position in the vf depends on the ____ of the eye (fixation)

A

0

convergence

8
Q

objects with 0 disparity are seen as ___ objects

objects w/ dispartiy diff from 0 are seen as ____

A

single

2-known as diplopia

9
Q

what is panum’s fusional area

A

the area close to the horopter that can generate objects w/ 0 disparity

10
Q

objects that are further away from the horopter have ___ angle of disparity (or abs dispartity) from objects that are closer to it

A

larger

11
Q

what does absolute disparity indicate

A

distance from the horopter (or the plane we are focusing on)

12
Q

what is relative dispartiy

what can this give us info about

A

the difference btwn the absolute disparities of 2 objects

-can give us info about the object’s position relatve to each other

13
Q

relative disparity remains always the ___ btwn 2 objects as we move our eyes and scan a scene

A

same

14
Q

-this constant diff in disparity gives us info about the ______ of objects

A

relative position

15
Q

for depth perception, we use _____

A

absolute and relative disparity

16
Q

for depth perception, we use absolute dispartiy for…

relative disparity for…

A

absolute: to judge an object’s distance from the plane of focus (horopter)
relative: judge the relative positions of objects

17
Q

what are the 2 kinds of dispartity

A

crossed and uncrossed

18
Q

what dispartiy is the objects always in front of the horopter

A

crossed disparity

19
Q

what disparity is it when the object is always behind the horopter

A

uncrossed

20
Q

crossed and uncrossed disparity is also called the ….

A

sign of disparity as we can tell whether an object is (+) or (-) the horopter

21
Q

what is the perception of depth called

A

stereopsis

22
Q

what is the geometrical description of how the objects are projected on the retina

A

disparity

23
Q

the stereoscope, view master, 3D movies and 3D tvs all use the same principles, they project lightly diff images on the retina causing…

A

disparity and therefore depth info

24
Q

what project different images on each eye through an optical system

A

stereogram (steroscope?) and view master

25
Q

how do 3D movies work with imgs of different color

A

2 slightly diff images are having diff color characteristics
usually one greenish one reddish
-by using tinted filters, one red and one green, the red img will be transmitted through the green filter and a diff image will be projected on each eye
-disparity btwn 2 diff image=depth perception

26
Q

how do 3D images work with polarized light

A

one image reflects polarized light in one direction while the other image reflects polarized light in another direction
-polarized lenses used that permit only one polarization to go through

27
Q

what is the passive method for 3D TV

A

polarized images are generated by the TV and again by using polarized glasses each image is projected only on one eye

28
Q

what is the active method for 3D TV

A

2 images are fast alternating on the screen

  • special glasses have an electronic componenet/shutter
  • each shutter is synchronized to only be open only when the first image is presented while the other remains shut and therefore there is no image on the other eye
  • the alternation must be higher thant he CFF so you don’t detect flicker
29
Q

how is steropsis used in military and medicine

A

military: usd to help appreciate the height, size, and shape of a target
medicine: taking x-rays from diff positions to create retinal dispartiy and would be able to see a tumor popping out

30
Q

all these methods provide steropsis bc of ____

but all the images we see (either in movie theatre, tv, or stereoscope) provide ______

A
disparity 
monocular cues (ex. occlusion)
31
Q

what are random-dot stereograms

A

presenting only binocular disparity w/ no monocular cues

-the fact that people perceive floating objects here suggest that disparity alone is a sufficient cue for stereopsis

32
Q

what is the corresponding problem

A

in order for disparity to work, the visual system matches the corresp points on the left and right retina
-for real world scenes, the visual system may match objects using specific features
ex. round with round, corner w/ corner
-most objects in the real world are discriminable (can tell part from other objects)
-our perceptual system corresponds one point to another even though it is complicated and our visual system calculates disparities
NO ANSWER TO CORRESPONDING PROBLEM.
-dont know how our visual system matches the corresponing points and calculates the disparities to create the perception of depth

33
Q

why is the visual system unable to calculate disparity for steropsis in stabismus

A

there are no corresponding points on the left and right retina

34
Q

the perception of ____ is affected by stereopsis

A

size

cant judge that an object is distant or near and therefore can’t judge its size

35
Q

what is the holway and boring experiment

A

aka hallway experiement

  • test stimulus can move back and forth and can change size so as to have the same visual angle on the retina
  • task for observer is to look at the stimulus and change the size of the comparison stimulus to be the same size as the test stimulus
36
Q

when the conditions were ______ the observers did a good job matching the sizes of the 2 stimuli

A

free-viewing

37
Q

size estimation is based on the….

A

physcial sizes of objects when depth cues are available

38
Q

size estimation is influenced by…

A

the objects visual angle when depth info isn’t available

39
Q

what is size constancy

A

our perception of an objects size is relatively constant, even when we see it from different distances (diff visual angles)

40
Q

what is it called when a mechanism uses a mathematical equation proposed to explain size constancy

A

size-distance scaling

41
Q

size-distance takes what into account

A

objects distance

42
Q

what is the equation to size-distnace scaling

which ones change together and what remians the same

A

S=a(RxD)

S=perceived img
R=retinal img
D=viewing dist
a=constan

R and D chnage together (direct rel’n) so S remains the same

43
Q

what is emmert’s law

A

the farther away an afterimage appears, the larger it will be perceived

44
Q

when the size constancy euqation is not applied correctly, forcing us to perceive different sizes, what is this called

A

misapplied size constancy

45
Q

what does the misapplied size contancy fail to explain

A

similar illusions w/ no obvsious perspceticve