Task 6 - Three Dimensions

Question 1

Cue approach to depth perception

Answer 1

it focuses on identifying information in the retinal image that is correlated with depth in the scen

Question 2

Occlusion

Answer 2

a signal, or cue, that one object is in front of another – we learn the connection between this cue and depth through our previous experience with the environment

Question 3

Three major different types of cues

Answer 3

Oculomotor: cues based on our ability to sense the position of our eyes and the tension in our eye muscles
Monocular: cues that work with one eye
Binocular: cues that depend on two eyes

Question 4

Oculomotor cues are created by

Answer 4

(1) convergence, the inward movement of the eyes that occurs when we look at nearby objects, and
(2) accommodation, the change in the shape of the lens that occurs when we focus on objects at various distances

Question 5

Monocular cues

Answer 5

Accommodation: described under oculomotor cues
Pictorial cues: which is depth information that can be depicted in a two-dimensional picture
Movement based cues: based on depth information created by movement

Question 6

Pictorial cues

Answer 6

sources of depth information that can be depicted in a picture

Question 7

Occlusion

Answer 7

Occlusion occurs when one object hides or partially hides another from view. The partially hidden object is seen as being farther away

Question 8

Relative height

Answer 8

objects that are below the horizon and have their bases higher in the field of view are usually seen as being more distant

Question 9

Relative size

Answer 9

when two objects are of equal size, the one that is farther away will take up less of your field of view than the one that is closer – also depends a little on a person’s knowledge of physical sizes

Question 10

Perspective convergence

Answer 10

the perceptual coming-together of parallel lines (as distance increases)

Question 11

Familiar size

Answer 11

judge distance based on our prior knowledge of the sizes of objects

Question 12

Atmospheric perspective

Answer 12

occurs when more distant objects appear less sharp and often have a slight blue tint –The farther away an object is, the more air and particles (dust, water droplets, airborne pollution) we have to look through, making objects that are farther away look less sharp and bluer than close objects

Question 13

Texture gradient

Answer 13

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

Question 14

Shadows

Answer 14

Shadows that are associated with objects can provide information regarding the locations of these objects – they also enhance the three-dimensionality of objects

Question 15

Two different motion-produced cues

Answer 15

(1) motion parallax and

(2) deletion and accretion

Question 16

Motion parallax

Answer 16

occurs when, as we move, nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly

Question 17

Deletion and accretion

Answer 17

Covering is deletion

Uncovering is accretion

Question 18

Binocular disparity

Answer 18

the difference in the images in the left and right eyes

Question 19

Corresponding retinal points

Answer 19

the places on each retina that would overlap if one retina could be slid on top of the other

Question 20

Horopter

Answer 20

which is an imaginary surface that passes through the point of fixation and indicates the location of objects that fall on corresponding points on the two retinas

Question 21

Angle of disparity

Answer 21

the difference between where the image falls on the eye and the corresponding point

Question 22

Absolute angle of disparity / absolute disparity

Answer 22

it provides information about the distances of objects — the amount of absolute disparity indicates how far an object is from the horopter — One of the properties of absolute disparity is that it changes every time the observer changes where he or she is looking

Question 23

Relative disparity

Answer 23

the difference between two objects’ absolute disparities — disparity information that remains the same no matter where an observer looks

Question 24

Frontal eyes

Answer 24

results in overlapping fields of view

Question 25

Lateral eyes

Answer 25

result in no overlapping visual fields and therefore cannot use disparity to perceive depth

Question 26

Binocular depth cells / disparity-selective cells

Answer 26

neurons that are tuned to respond to specific amounts of disparity. The first research on these neurons described neurons in the striate cortex (V1) that responded to absolute disparity

Question 27

Visual angle

Answer 27

the angle of an object relative to the observer’s eye – when a person moves closer the visual angle becomes larger – The visual angle tells us how large the object will be on the back of the eye

Question 28

Size consistency

Answer 28

This principle states that our perception of an object’s size remains relatively constant, even when we view an object from different distances, which changes the size of the object’s image on the retina

Question 29

Size-distance scaling

Answer 29

the mechanism that takes an object’s distance into account

Question 30

Emmert’s law

Answer 30

The relationship between the apparent distance of an afterimage and its perceived size

Question 31

Müller-Lyer illusion

Answer 31

the right vertical line appears to be longer than the left vertical line, even though they are both exactly the same length (with the arrows pointing in and out)

Question 32

Misapplied size constancy scaling

Answer 32

size constancy normally helps us maintain a stable perception of objects by taking distance into account – Gregory suggests that the fins on the right line make this line look like part of an inside corner, and that the fins on the left line make this line look like part of an outside corner

Question 33

Conflicting cues theory

Answer 33

our perception of line length depends on two cues:

(1) the actual length of the vertical lines, and (2) the overall length of the figure

Question 34

Ponzo (or railroad track) illusion

Answer 34

both animals are the same size on the page, and so have the same visual angle, but the one on top appears longer

Question 35

Ames room

Answer 35

causes two people of equal size to appear very different in size
The reason for this erroneous perception of size lies in the construction of the room

Question 36

Moon illusion

Answer 36

The enlargement of the moon at the horizon compared to the elevated moon – although in both cases they have the same visual angle

Question 37

Apparent distance theory

Answer 37

the moon on the horizon appears more distant because it is viewed across the filled space of the terrain, which contains depth information; but when the moon is higher in the sky, it appears less distant because it is viewed through empty space, which contains little depth information

Question 38

Angular size contrast theory

Answer 38

the moon appears smaller when it is surrounded by larger objects – Thus, when the moon is elevated, the large expanse of sky surrounding it makes it appear smaller. However, when the moon is on the horizon, less sky surrounds it, so it appears larger