Problem 6

Question 1

Occlusion

Pictorial cue

Answer 1

Occurs when one object partially hides another from view

–> partially hidden object is perceived to be more distant

Question 2

Oculomotor cues

Answer 2

Created by

1. CONVERGENCE
   - -> inward movement of the eyes that occurs when we look at nearby objects
2. ACCOMMODATION
   - -> the change in the shape of the lens, when focusing on objects

=> cues based on our ability to sense the position of our eyes

Question 3

Monocular cues

Answer 3

Cues that work with one eye

a) accommodation
b) pictorial cues
c) motion produced cues

Question 4

Pictorial cues

Answer 4

Sources of depth information that can be depicted in a two dimensional picture

–> cues are stationary/fixed

Question 5

Relative size

Pictorial cue

Answer 5

When 2 objects are of equal size, the one farther away will take up less of our view than the one closer

–> cue depends on a persons knowledge of physical sizes

Question 6

Familiar size

Pictorial cue

Answer 6

Cues used when judging the distance based on prior knowledge of the size of objects

Question 7

Texture gradient

Pictorial cue

Answer 7

Elements equally spaced in a scene appear to be more closely packed as distance increases

Question 8

Relative height

Pictorial cue

Answer 8

Objects with their bases closer to the horizon are usually seen as being more distant

Question 9

Perspective convergence

Pictorial cue

Answer 9

Cue experienced when looking down parallel lines that appear to converge in distance

Question 10

Atmospheric perspective

Pictorial cue

Answer 10

Occurs when distant objects appear less sharp than nearer objects, with a slight blue tint

–> works above 30 m

Question 11

Shadows

Pictorial cue

Answer 11

Decreases in light intensity caused by a blockage of light that provide info about the location of objects

Question 12

Motion produced cues

Answer 12

Cues that emerge when we start moving, that enhance our perception of depth

–> works at close + medium ranges

Question 13

Motion parallax

Motion-produced cue

Answer 13

Occurs when nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly

ex.: moving nearby cars seem to speed away in a blur, whereas those farther away seem to be moving slowly

Question 14

Deletion + Accretion

Answer 14

As one moves sideways, some things become covered (=deletion) and some become uncovered (= accretion)

Question 15

Stereoscopic vision

Answer 15

Ability to use disparity between 2 eyes as a cue to depth

Question 16

Binocular disparity

Answer 16

Describes the differences between two retinal images of the same scene

–> basis for stereopsis

Question 17

Corresponding retinal points

Answer 17

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

Question 18

Horopter

Answer 18

Imaginary circle that passes through the point of focus

–> the surface has 0 disparity

Question 19

Non-corresponding points

Answer 19

Images of objects that are not on the horopter fall on non-corresponding points

Question 20

Absolute disparity

Answer 20

The degree to which these objects deviate from falling on corresponding points

–> determined by measuring the angle between where the CP would be located and where it is actually located

Question 21

Angle of disparity

Answer 21

Amount of absolute disparity

–> provides info about the objects distance from the horopter

Question 22

Crossed disparity

Answer 22

Sign of disparity produced by objects in front of the horopter

1. You would need to “cross” your eyes to fixate on the object in front of you
2. Objects appear to be displaced to the right in the left eye and vice versa

Question 23

Uncrossed disparity

Answer 23

Sign of disparity produced by objects behind the horopter

–> objects seem to be displaced to the right in right eye + same for left eye

Question 24

Relative disparity

Answer 24

The difference in absolute disparities of objects in a scene remains the same as an observer looks around the scene

–> helps indicate where objects are located relative to others

Question 25

Random dot stereogram

Answer 25

Stereogram made of a large number of randomly placed dots, that contains no monocular cues to depth

–> shows that disparity alone can result in depth perception

Question 26

Correspondence problem

Answer 26

Refers to the question of how the visual system matches the parts of the images in the left and right eyes that correspond to one another?

Question 27

Binocular depth cells

Disparity selective cells

Answer 27

Respond best when stimuli presented to either eye create a specific degree of absolute disparity

Question 28

Which cortical areas are involved in depth perception ?

Answer 28

Depth perception starts in primary visual area and extends into different areas in the ventral + dorsal streams

Question 29

Selective rearing

Answer 29

If an animal is reared in an environment that contains only certain types of stimuli, neurons that respond to these stimuli will become more prevalent

–> explains why we respond predominantly to vertical + horizontal lines

Question 30

Size constancy

Answer 30

Refers to the fact that our perception of an objects size is relatively constant, even when we view the object from different distances

Question 31

Size distance scaling

Answer 31

To perceive the actual size of an object the observer combines the information of

a) the retinal size of the object
b) the objects distance

Question 32

Equation for size distance scaling

Answer 32

S = K ( R x D )

S –> objects perceived size

K –> constant

R –> size of retinal image

D –> Perceived distance of object

Question 33

Müller - Lyer illusion

Answer 33

Illusion in which two lines of equal length appear unequal depending on whether angular lines forming arrowheads at each end point toward or away from each other

–> because our perception depends on the overall length of the figure

Question 34

Which constraints help us solve the correspondence problem ?

Answer 34

1. Uniqueness

–> a feature in the world will be represented exactly once in each retinal image

2. Continuity

–> except at the edges of objects, neighboring points in the world lie at similar distances from the viewer