Space Perception

Question 1

Euclidian Geometry

Answer 1

Parallel lines remain parallel as they extend into space

Question 2

True or False

The images projected into the retina are non-euclidean

Answer 2

True

Question 3

How do we perceive space?

Answer 3

1. Monocular cues
2. Binocular vision and Stereopsis

Question 4

Name the monocular cues seen in class

Answer 4

1. Occlusion
2. Metrical depth cue
3. Nonmetrical depth cue
4. Relative size
5. Familiar Size
6. Relative height
7. Texture Gradient
8. Relative metrical depth cue
9. Linear Perspective
10. Vanishing point
11. Areal Perspective
12. Motion Parallax
13. Optic flow

Question 5

Occlusion

Answer 5

A cue to relative depth order in which, for example, an object partially obstructs the view of another object.

Question 6

Metrical Depth Cue

Answer 6

A depth cue that provides quantitative information about distance in the third dimension.

Question 7

Nonmetrical Depth Cue

Answer 7

A depth cue that provides information about the depth order but not the depth magnitude

Question 8

Relative Size

Answer 8

A comparison of size between two items without knowing the absolute size of any of them.

All things being equal, we assume that smaller objects are further away from use than larger objects.

Question 9

Familiar Size

Answer 9

A comparison of size between two items while knowing the absolute size of one of them.

In this case, we can infer the absolute distance since we know the exact size of one of the objects.

Question 10

Relative Height

Answer 10

For objects touching the ground, those higher in the visual field seem further away.

In the sky above the horizon, objects appearing lower in the visual field seem farther away.

Question 11

Texture Gradient

Answer 11

A depth cue based on the geometric fact that objects of the same size form smaller, closer spaced images the farther they get.

Texture gradients result from the combination of relative size cues and relative height cues

Question 12

True or False

Metrical cues give the visual system more information than nonmetrical cues.

Answer 12

True

Question 13

Relative Metrical Depth Cue

Answer 13

A depth cue that could specify, for example, that object A is twice as far away as object B without providing information about the absolute distance to either A or B.

Question 14

Linear Perspective

Answer 14

Parallel lines in the threedimensional world will appear to converge in the two-dimensional image as they extend into the distance.

Linear Perspective also results from a combination of the cues of relative size and relative height.

Question 15

Vanishing Point

Answer 15

The apparent point at which the parallel lines receding in-depth converge.

Question 16

Areal Perspective

Answer 16

A depth cue based on the implicit understanding that light is scattered by the atmosphere.

Further objects appear fainter, bluer and less distinct.

Question 17

Motion Parallax

Answer 17

Images closer to the observer move faster than the images farther from the observer.

The brain uses this to calculate the distance between objects in the environment.

Head movements and any other relative movements between observers and objects reveal motion parallax cues.

Question 18

Optic Flow

Answer 18

The apparent motion of objects in a visual scene produced by the relative motion between the observer and the scene.

Objects in the focus of the expansion will not move.

Objects closer the observer move more rapidly.

Question 19

Monocular to Binocular Cues

Answer 19

Accommodation

The process by which the eye changes its focus.

Convergence: The ability of the two eyes to turn towards each other. Usually to see objects that are closer.

Divergence: The ability of the two eyes to turn outwards. Usually to see objects that are farther away.

Question 20

Binocular Vision and Stereopsis

Answer 20

1. Binocular Summation
2. Binocular Disparity
3. Corresponding Retinal Points
4. Vieth-Muller Circle (Horopter)
5. Diplopia
6. Panum’s Fusional Area
7. Crossed Disparity
8. Uncrossed Disparity

Question 21

Binocular Summation

Answer 21

The combination of signals from each eye in ways that make performance on many tasks better with both eyes than with either eye alone.

Question 22

Binocular Disparity

Answer 22

The differences between the two retinal images of the same scene.

Disparity is the basis of stereopsis, a vivid perception of the threedimensional world that is not available in monocular vision.

Question 23

Corresponding Retinal Points

Answer 23

A geometrical concept stating that point on the retina of each eye where the monocular retinal images of a single object are formed are at the same distance from the fovea in each eye.

Question 24

Vieth-Muller Circle

(Horopter)

Answer 24

The location of objects whose image lies on the corresponding points.

The surface of zero disparity.

Question 25

Diplopia

Answer 25

Double vision.

If visible in both eyes, stimuli falling outside the Panum’s Fusional area will appear diplopic.

Question 26

Panum’s Fusional Area

Answer 26

The region of space in front and behind the horopter where binocular single vision is possible.

Question 27

Crossed Disparity

Answer 27

The sign of disparity created by objects in front of the plane of the horopter.

Images in the front of the horopter are displayed to the left of the right eye and to the right of the left eye.

Question 28

Uncrossed Disparity

Answer 28

The sign of disparity created by objects behind the plane of the horopter.

Images behind the horopter are displaced to the right in the right eye and displaced to the left in the left eye.

Question 29

True or False

Different binocular neurons in V1 encode all categories of retinal disparity.

Answer 29

True

Question 30

True or False

The binocular neurons in V1 that encode all categories of retinal disparity aren’t placed in a particular structure

Answer 30

False

They are organized as columns.

Question 31

Notice:

The binocular neurons in V1 that encode all categories of retinal disparity allow perceiving depth within Panum’s Fusional Area

Question 32

Stereoscope

Answer 32

A device for presenting an image to an eye and another image to the other eye.

Question 33

Correspondence Problem

Answer 33

In binocular vision, the problem of figuring out which bit of the image in the left eye should correspond with which bit in the right eye.

Question 34

Do we have to recognize objects to have stereopsis?

Answer 34

No,

An example is we have 2 teapots, and they are identical but one is located further away. So how does our visual system knows that the far teapots are the same, similarly for the near ones?

Question 35

Random Dot Stereogram (RDS)

Answer 35

A stereogram made out of a great number or randomly placed dots.

• RDSs contain no monocular cues to depth
• Stimuli visible stereoscopically in RDSs are cyclopean stimuli.
• If the “object” on the right eye is positioned to the left of the object on the left eye (if there is crossing), the object will be perceived in front of the background (and vice-versa)

Question 36

Cyclopean

Answer 36

Referring to stimuli that are defined by binocular disparity alone.

Question 37

True or False

Object recognition happens after binocular integration.

Answer 37

True

Question 38

Binocular Rivalry

Answer 38

The competition of the two eyes for control of visual perception, which is evident when completely different stimuli are presented to both eyes.