Topic 8: Perceiving Depth and Size

Question 1

How are depth and size related?

Answer 1

An inaccurate perception of depth can lead to an incorrect perception of size

Question 2

Your ability to perceive these distances in the 3D environment is based entirely upon…

Answer 2

The image (2D) that is hitting your retina.

Question 3

What are the three major groups of depth cues?

Answer 3

Oculomotor cues
Monocular cues
Binocular cues

Question 4

Cues that rely upon on our ability to sense the position of our eyes and sense the tension in our eye muscles

Answer 4

Oculomotor cues

Question 5

What are the two types of oculomotor cues?

Answer 5

Convergence
Accomodation

Question 6

inward eye movements that occur when we look at nearby objects

Answer 6

Convergence

Question 7

change in the shape of the lens that occurs when we focus on objects at various distance

Answer 7

Accommodation

Question 8

Cues for depth perception that can work when we use only one eye

Answer 8

Monocular cues

Question 9

What are the two broad categories that monocular cues can be divided into?

Answer 9

Pictorial cues
Movement-based cues

Question 10

What are the 7 pictorial monocular cues?

Answer 10

Occlusion
Relative height
Familiar size
Relative size
Perspective convergence
Texture gradients
Shadows

Question 11

Depth cue in which one object hides or partially hides another object from view, causing the hidden object to be perceived as being farther away

Answer 11

Occlusion

Question 12

Objects that are higher in the visual field are (usually) further away than objects lower in the visual field

Answer 12

Relative height

Question 13

Judgment of a distance based on previous knowledge of the size of objects

Answer 13

Familiar size

Question 14

When two objects are of equal size, the one that is farther away will take up less of the field of view

Answer 14

Relative size

Question 15

Perception that parallel lines in the distance converge as the distance increases

Answer 15

Perspective convergence

Question 16

Objects appear more textured when they are closer to us, with less texture being apparent as distance increases

Answer 16

Texture gradients

Question 17

Help us better determine the location and placement of objects relative to others

Answer 17

Shadows

Question 18

What are the two movement-based monocular cues?

Answer 18

Motion parallax

Deletion and accretion

Question 19

As we move, nearby objects appear to move rapidly across our visual field whereas far away objects appear to move more slowly

Answer 19

Motion parallax

Question 20

Moving sideways, some things become covered, and some things become uncovered

Answer 20

Deletion and accretion

The object that deletes and accretes = perceived as being farther away

Question 21

Basis of stereoscopic vision is…

Answer 21

Binocular disparity

Question 22

Occurs when the retinal images of an object fall on different points on the two retinas

Answer 22

Binocular disparity

Question 23

Points on the retina that would overlap if the eyes were superimposed on top of each other

Answer 23

Corresponding retinal points

Question 24

Objects that fall on corresponding points in each eye are located on the…

Answer 24

Horopter

Question 25

Objects that do not fall on the horopter fall on…

Answer 25

non-corresponding retinal points

Question 26

What occurs when objects fall in front of, or behind, the horopter?

Answer 26

Generates an angle of disparity between the eyes = “binocular disparity”

Question 27

What is the relationship between location of an object relative to the horopter and the size of the angle?

Answer 27

If the angle is large = object is closer than the horopter

If the angle is small = object is farther than the horopter

Question 28

The idea that binocular disparity provides information about the position of objects in space suggests that…

Answer 28

There should be neurons somewhere in our brains that fire to different amounts of disparity.

Question 29

Binocular depth cells/disparity selective cells are present in…

Answer 29

V1

Question 30

Explain the function of inocular depth cells

Answer 30

Preferentially respond to different amounts of disparity

Some will fire more to objects that are in front of the horopter

Some will fire more to objects that are behind the horopter

Question 31

Why are binocular cues most useful?

Answer 31

Any distance for any object

Question 32

Explain the relationship between size and visual angles

Answer 32

When far away, the visual angle is small, so the object is perceived as being small.

When closer, the visual angle increases, so the object is perceived as being big.

Question 33

Our perception of size remains relatively constant, even when the distance changes, or the visual angle on the retina changes.

Answer 33

Size constancy

Question 34

Environmental cues that can be used to judge an object’s size

Answer 34

Frames of reference

Question 35

Judging the size of one object by comparing them to the size of an object we are already, or more, familiar with

Answer 35

relative and familiar size