Task 6: 3D

Question 1

Perception of objects and scene is based on what kind of retinal image?

Answer 1

2D retinal image

Question 2

What do cues explain?

Answer 2

How retinal 2D image gives depth

Question 3

Oculomotor cues

- where do they work?

Answer 3

Cues based on our ability to sense the position of our eyes and tension in our eye muscles
- close range (up to 2 meters)

Question 4

Name 2 oculomotor cues

Answer 4

1. convergence

2. accomodation

Question 5

Convergence

Answer 5

Inward movement of eyes that occurs when we look at nearby objects.

Question 6

Accommodation

Answer 6

Change in shape of lens (lens flattens) that occurs when we focus on objects at various distances

Question 7

Monocular cues

Answer 7

Cues that work with one eye. These include accommodation, pictorial cues and motion-produced cues.

Question 8

Occlusion (monocular pictorial cue)

Answer 8

Occurs when one object (partially) hides another from view

Question 9

Relative size (monocular pictorial cue)

Answer 9

When two objects are of equal size, the one farther away will take up less of our field of view than the one closer.

Question 10

Familiar size (monocular pictorial cue)

Answer 10

Cue used when judging distance based on prior knowledge of size of objects.

Question 11

Texture gradient (monocular pictorial cue)

Answer 11

Elements equally spaced in scene appear to be more closely packed as distance increases.

Question 12

Shadows (monocular pictorial cue)

Answer 12

Decreases in light intensity caused by blockage of light that provide info about location of objects.

Question 13

Atmospheric pressure (monocular pictorial cue)

Answer 13

Occurs when distant objects appear less sharp than nearer objects, with a slight blue tint. Works above 30m

Question 14

Perspective convergence (monocular pictorial cue)

Answer 14

Cue experienced when looking down parallel lines that appear to converge in distance.

Question 15

Relative height (monocular pictorial cue)

Answer 15

Objects with their bases closer to horizon are usually seen as being more distant. Works from 2m.

Question 16

Motion-produced cues

Answer 16

Cues that emerge when we start moving, that enhance our perception of depth. Both work at close and medium ranges (up to 20 meters)

Question 17

Motion parallax (monocular motion-produced cue)

Answer 17

Occurs when nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly.

Question 18

Deletion and accretion (monocular motion-produced cue)

Answer 18

As an observer moves sideways, some things become covered (= deletion), and others become uncovered (= accretion).

Question 19

Binocular cues

Answer 19

rely on info from both eyes

Question 20

Stereoscopic vision

Answer 20

ability to use binocular disparity as a cue to depth

Question 21

Strabismus

Answer 21

misalignment of the eyes (cross eye), visual system suppresses vision in one of the eyes to avoid double vision so the person sees the world with one eye at a time

Question 22

Binocular disparity

Answer 22

Differences between two retinal images of same scene. Basis for stereoscopic vision

Question 23

Corresponding retinal points

Answer 23

points on retina that overlap if eyes are superimposed on each other

Question 24

Horopter

Answer 24

Imaginary circle that passes through point of focus. Surface of zero disparity.

Question 25

Non-corresponding points

Answer 25

Images of objects that are not on horopter fall on noncorresponding points.

Question 26

Absolute disparity

Answer 26

Degree to which these objects deviate from falling on corresponding points. It is determined by measuring angle between where corresponding point would be located and where it is actually located.

Question 27

Angle of disparity

Answer 27

angle between corresponding (0) and non-corresponding (not 0) retinal points

Question 28

Crossed disparity

Answer 28

Sign of disparity produced by objects in front of horoptor. Objects located in front of horopter appear to be displaced to the left in right eye, and to the right in left eye.

Question 29

Uncrossed disparity

Answer 29

Sign of disparity produced by objects behind horoptor. Objects located behind horopter appear to be displaced to the right in right eye and to the left in left eye.

Question 30

Relative disparity

Answer 30

Difference in absolute disparities of objects in a scene that remains the same as an observer looks around a scene.

Question 31

Stereopsis is related to ________, the experience of depth created by disparity

Answer 31

perception

Question 32

Stereopsis

Answer 32

impression of depth that results from information provided by binocular disparity

Question 33

Stereoscope

Answer 33

Device for simultaneously presenting slightly different images to one eye and the other, producing an illusion of depth because it creates same binocular disparity that occurs when a person views the scene naturally.

Question 34

Random-dot stereogram

Answer 34

Stereogram made of large number of randomly placed dots, that contains no monocular cues to depth. Aimed at showing that disparity alone can result in depth perception.

Question 35

Correspondence problem

Answer 35

Visual system must compare images of left and right retinas in order to calculate the amount of disparity.

Question 36

Binocular depth cells (disparity-selective cells)

Answer 36

– Respond best when stimuli presented to left and right eyes create specific degree of absolute disparity.

Question 37

Neurons in the ___ are sensitive to absolute disparity

Answer 37

primary receiving area

Question 38

Neurons in the ___ and other areas are sensitive to relative disparity

Answer 38

temporal lobe

Question 39

Our perception of ___ can be affected by our perception of ____

Answer 39

size, depth

Question 40

Visual angle

Answer 40

Angle of object relative to observer’s eye that is determined by extending lines from person to the lens of observer’s eye.

Question 41

Size constancy

Answer 41

Fact that our perception of object’s size is relatively constant, even when we view object from different distances.

Question 42

Size-distance scaling

Answer 42

Idea that perceiver combines the size of object formed on retina and its distance to perceive the actual size of an object

Question 43

Equation for size distance scaling

Answer 43

s = k ( r x d )

s= perceived size
k= constant 
r= retinal image size
d= perceived distance

Question 44

Emmert’s law

Answer 44

The farther away an afterimage appears, the larger it will seem.

Question 45

Misapplied size constancy scaling (gregory 66)

Answer 45

Explanation for this effect proposing that mechanisms that help us perceiving in 3-D world sometimes create illusions when applied to objects drawn on 2-D surface.

Question 46

Conflicting cues theory (day 90)

Answer 46

– Our perception of line length depends on (1) actual length of vertical lines and (2) overall length of figure.

Question 47

Where are the cells for

a) signalling disparity; binocular disparity starts here
b) extracting illusory contours

Answer 47

a) v1

b) v2

Question 48

What neurons are responsible for stereopsis?

Answer 48

V1 V2 V5

Question 49

Neurons responsible for pictorial cues

Answer 49

V2