Depth and Size Perception

Question 1

What is absolute distance judgment?

Answer 1

Egocentric localization - you to object

Question 2

What is relative distance judgment?

Answer 2

Requires object-relative localization - object to object

Question 3

What are pictorial depth cues?

Answer 3

Can be extracted from a 2D image
Occlusion
Shading and shadows
Atmospheric pressure
Relative size
Familiar size
Linear perspective
Relative height
Texture gradient

Question 4

What is occlusion?

Answer 4

If object A covers part of object B, then A is seen as closer than B

Question 5

What are shading and shadows?

Answer 5

Indicates which surfaces are facing the light source and which are not

Question 6

What is atmospheric pressure?

Answer 6

Greater absolute distance makes objects appear fuzzier, bluer

Question 7

What is relative size?

Answer 7

Same size object further away produces a smaller visual angle

Question 8

What is familiar size?

Answer 8

Knowledge of object’s actual size influences the perception of its distance

Question 9

What is linear perspective?

Answer 9

Apparent convergence of receding parallel lines at a vanishing point

Question 10

What is the key point in linear perspective?

Answer 10

The vanishing point which determine the horizon

Question 11

What is relative height?

Answer 11

Below the horizon, higher objects appear father away
Above the horizon, lower objects appear further

Question 12

What is texture gradient?

Answer 12

Texture elements appear smaller and more densely arranged as they get farther away

Question 13

What are motion-based depth cues?

Answer 13

Motion parallax
Deletion
Accretion

Question 14

What is motion parallax?

Answer 14

As an observer moves perpendicular to an object, nearby objects appear to move past more rapidly than faraway objects

Question 15

What is deletion?

Answer 15

Background object is occluded by foreground object moving in front of it

Question 16

What is accretion?

Answer 16

Background object is uncovered by foreground object moving out of the way

Question 17

What are oculomotor depth cues?

Answer 17

Accommodation
Convergence

Question 18

What does a smaller convergence angle result in?

Answer 18

Farther object

Question 19

What does a larger convergence angle result in?

Answer 19

Closer object

Question 20

How do depth cues interact?

Answer 20

Depth cues are rarely used alone
Accuracy in estimating distance is an additive relation between depth cues
Perception of depth is stronger with more cues

Question 21

What is binocular disparity?

Answer 21

Retinal images of an object fall on disparate points on each eye’s retina

Question 22

What is stereopsis?

Answer 22

Perception of depth based on retinal disparity alone

Question 23

What is a horopter?

Answer 23

Imaginary surface passing through a fixation point

Question 24

What happens if the distal stimulus lies on the horopter?

Answer 24

Then the proximal stimulus will fall on corresponding points on each retina = no disparity

Question 25

What happens if a distal stimulus is not on the horopter?

Answer 25

Then the proximal stimulus produces disparity

Question 26

What is the degree of disparity?

Answer 26

The distance between points on each retina

Question 27

What would result in greater disparity?

Answer 27

Objects being farther from the horopter

Question 28

What are random-dot stereograms?

Answer 28

Each eye sees the same pattern of random dots - with one exception Central region in each pattern is shifted over and this creates retinal disparity The shifted region is perceived as floating above the background

Question 29

What are single-image random-dot stereograms?

Answer 29

Retinal disparity in autosterograms is produced in opposite was form random-dot stereograms Usually, two separate images are directed onto the same part of each retina A single image is observed so that it falls on two different parts of each retina in RIRDS

Question 30

How to see an autostereogram?

Answer 30

Have a small angle of convergence Look at autostereogram but don't change the convergence; should see two overlapping images Change accommodation to bring images into focus keeping convergence constant Change convergence until repeating parts of the pattern line up horizontally

Question 31

What is the correspondence problem?

Answer 31

How is it determined which dots in the left eye match which dots in the right eye, to fuse the two images into one percept?

Question 32

What are some solutions to the correspondence problem?

Answer 32

A neural-network solution that depends on a number of factors including similarity; matches are made only between elements that are similar No widely accepted solution

Question 33

What was Walk and Gibson's cliff experiment?

Answer 33

Started with a visual cliff Mammals avoided the cliff, turtles did not There is an innate component to avoiding cliffs

Question 34

What was Campos, Bertenthals, and Kermoians experiment?

Answer 34

Younger, precrawling infants tested Experiment group given walker experience, control group got no experience Dangled infants over deep side and measured HR The walker group experienced fear, non-experienced did not Crawling experience more important than age Depth perception develops via interaction of appropriate experience and innate factors

Question 35

What are critical/sensitive periods?

Answer 35

Aspects of depth perception develop at certain chronological ages, given proper environmental experience

Question 36

What was the task of Holway and borings experiment?

Answer 36

Adjust size of comparison circle to match that of various sized test circles, places at different distances Visual angle of all test circles is 1°`

Question 37

What was part 1 of Holway and borings experiment?

Answer 37

Normal viewing If test circle was large and far, observers chose large comparisons

Question 38

What was part 2 of Holway and borings experiment?

Answer 38

Depth cues eliminated Observers looked at test circles through a peephole All stimuli had the same visual angle, so the size comparison matched the visual angle of the test circle, not the size of the test circle

Question 39

What happens as the distance from a given object increases?

Answer 39

The retinal image becomes smaller but we do not perceive that

Question 40

What is size-distance scaling?

Answer 40

Distance taken into account when perceiving size

Question 41

What must be available for size constancy?

Answer 41

Distance and depth cues or else errors will occur

Question 42

How do illusions occur?

Answer 42

Caused by misapplied size constancy

Question 43

Which illusion is weaker in children?

Answer 43

Muller-Lyer illusion

Question 44

What is the moon illusion?

Answer 44

Horizon moon seems to be larger than overhead moon even though the retinal size and the actual distance are constant Misjudgment of the moon's size resulting from a misperception of distance

Question 45

What is apparent-distance theory?

Answer 45

Objects on the horizon, viewed across the filled space of the terrain, should appear to be further away Objects overhead, seen through the empty space of sky, should appear closer

Question 46

What is the eye elevation hypothesis?

Answer 46

Moving eyes upwards makes objects appear smaller

Question 47

What is Emmert's law?

Answer 47

Perceived size of an object having a constant visual angle is proportional to the perceived distance of the object

Question 48

What is the illusion of velocity and size?

Answer 48

The larger the object, the more slowly it appears to be moving

Question 49

What is the illusion of linear perspective?

Answer 49

Increased perceived distance of the train, contributing to an overestimation of the safe time interval

Question 50

What is the deceptive geometry of collisions?

Answer 50

As distance to train decreases, the visual angle of the train increases in size The rate of increase in size is hyperbolic Overestimation of safe time interval