6. Depth Perception

Question 1

What is the inverse problem of depth perception?

Answer 1

the retinal image can be caused by numerous possible configurations of the world

Question 2

What are the 4 main forms of depth cue?

Answer 2

Binocular, motion, pictorial, oculomotor

Question 3

Binocular disparity occurs because:

Answer 3

a scene falls on different parts of the retina between the two eyes due to the eyes being in different positions.

Question 4

Binocular disparity is measured in what unit?

Answer 4

Degrees

Question 5

Binocular disparity is directly proportional to __, and inversely proportional to __

Answer 5

Depth

Squared viewing distance

Question 6

Motion cues: what is motion parallax?

Answer 6

Motion on the retina caused by our movement relative to other things

Question 7

Motion cues: what is Kinetic depth?

Answer 7

motion on the retina due to objects moving relative to us. Closer parts of an object will move faster than far parts

Question 8

Pictorial cues: how does texture indicate depth?

Answer 8

sunflower field analogy: the more texture, the further something is away

Question 9

Pictorial cues: how does elevation indicate depth?

Answer 9

Things that are lower down tend to be closer to us

Question 10

Pictorial cues: how does relative size of objects indicate depth?

Answer 10

the bigger something is, the closer it is

Question 11

Pictorial cues: how does perspective indicate depth?

Answer 11

lines converge as things get further away

Question 12

Pictorial cues: how does shading indicate depth?

Answer 12

light and dark shading can show convexity or concavity

Question 13

Pictorial cues: how does occlusion indicate depth?

Answer 13

objects that are occluding/hiding others must be in front (nearer to us)

Question 14

Oculomotor cues: what is convergence and how does it signal depth?

Answer 14

• eyes bend in when focussing on near object

- have to converge more if object is close, muscles signal this to the visual system

Question 15

Oculomotor cues: what is accommodation and how does it signal depth?

Answer 15

• lens enables light to be focused on the retina

- lens gets fatter for close objects and thin for far objects through the ciliary muscles, which send signals to brain

Question 16

What are the problems with depth perception cues? (2)

Answer 16

• the cues are ambiguous

- how are all the different cues combined?

Question 17

Using prior knowledge and experience of physical properties of the world (top-down processing) can solve which problem of depth perception?

Answer 17

Ambiguity (retinal image could be created by numerous configurations)

Question 18

In perspective, we use top down assumptions that lines in the world tend to be __?

Answer 18

parallel or perpendicular

Question 19

In shading, we use what assumption about light in the world?

Answer 19

It comes from above

Question 20

What assumptions are made about surface textures in depth perception?

Answer 20

They are isotropic (unbiased orientation) and homogeneous (same density across the surface)

Question 21

What do the assumptions of texture being isotropic and homogeneous allow us to believe?

Answer 21

Changes in texture must be due to the 3D orientation of the object

Question 22

When using the depth cue of elevation, we assume that objects rest on the __

Answer 22

Ground (due to gravity)

Question 23

Sometimes, assumptions are not correct leading to perceptual illusions. These assumptions are called:

Answer 23

Erroneous assumptions

Question 24

Multi-cue integration: what is compromise?

Answer 24

take an average of the information from both cues, but the average will be biased toward the most reliable cue

Question 25

Multi-cue integration: what is dominance?

Answer 25

trusting one cue and ignoring the other if they are providing very different information

Question 26

Multi-cue integration: what is interaction?

Answer 26

use of a cue to make another cue less ambiguous

Question 27

The Ames Room illusion can be explained by which form of multi-cue integration, and how?

Answer 27

Dominance: we choose the invalid cue (perspective) and ignore the correct one (relative size).

Question 28

Interaction: binocular disparity can disambiguate which pictorial cue?

Answer 28

texture - if something is convex or concave

Question 29

There is evidence that interaction (cues being disambiguated by less ambiguous cues) occurs before cues being compromised: True or False?

Answer 29

True

Question 30

Conflict between these types of depth cue can lead to headache, eye strain, and nausea:

Answer 30

Binocular and oculomotor cues