Vision part 3

Question 1

Vergence

Answer 1

Eye convergence for near objects, divergence for distant ones.

Question 2

Ciliary muscles adjust lens shape for focus.

Answer 2

Accomodation

Question 3

The _____ system keeps tract of degree of accommodation, and uses this cue to infer depth

Answer 3

Nervous

Question 4

Absolute depth perception (unlike pictorial cues, can put absolute estimate of object’s distance )

Answer 4

Vergence limit: Reliable up to ~2m. After that, no divergence.
Accommodation limit: Active up to ~6m (beyond this is optical infinity)

Question 5

Stereopsis

Answer 5

Rich impression of depth that we get from seeing with both eyes.

Question 6

Binocular Disparity

Answer 6

The slight difference in the images perceived by each eye due to their horizontal separation, which the brain uses to calculate depth and perceive a three-dimensional view of the environment.

Question 7

Vieth-Müller Circle

Answer 7

• imaginary geometric circle in visual space that passes through the point of fixation and the optical centers of both eyes.

Question 8

The points in the Vieth-Müller Circle show the theoretical locations of objects that produce corresponding retinal points in both eyes, resulting in …

Answer 8

no binocular disparity and appearing at the same depth as the fixation point

Question 9

The fixation point P is reflected on the _____

Answer 9

Fovea

Question 10

A point that falls on the Vieth-Muller circle will be projected …

Answer 10

Exactly in the same point in both eyes.

Question 11

A point that falls outside the Vieth-Muller circle will be projected…

Answer 11

At a different point in each eye

Question 12

The principle of corresponding or non corresponding retinal points is used to infer ____

Answer 12

Depth

Question 13

Horopter

Answer 13

Spatial region in visual space where objects project images onto corresponding retinal points in both eyes.

Question 14

Objects on the horopter appear to be at the same depth as the point of fixation and are perceived without ….

Answer 14

Binocular disparity

Question 15

In theory, for every point outside the horopter, we should have…

Answer 15

Double vision

Question 16

The horopter can take different shapes depending on the viewing conditions, such as the distance of fixation. It includes the … under idealized conditions.

Answer 16

Vieth-Müller Circle

Question 17

Panum’s fusional area

Answer 17

Region in visual space around the horopter where slight binocular disparities can still be fused by the brain to produce a single, unified perception of depth.

Question 18

Objects outside Panum’s fusional area may appear as _____(diplopia)

Answer 18

Double

Question 19

Crossed disparity occurs when an object is ____closer/farther to you than the point of fixation.

Answer 19

Closer

Question 20

When the object is in front of the horopter (crossed disparity), the image of the object falls on the ____ side of the retina in both eyes.

Answer 20

outer (temporal)

Question 21

Why is crossed disparity called that ?

Answer 21

from the left eye’s view, the object is located to the right of the fixation point, and from the right eye’s view, it is located to left of the fixation point

Question 22

Uncrossed disparity

Answer 22

When an object is farther away from you than the point of fixation.

Question 23

When the object is behind the horopter (uncrossed disparity), the image of the object falls on the _____ side of the retina in both eyes.

Answer 23

inner (nasal)

Question 24

Why is uncrossed disparity considered “uncrossed” ?

Answer 24

From the left eye’s view, the object is located to the left of the fixation point, and from the right eye’s view, it is located to the right of the fixation point.

Question 25

Different binocular neurons in V1 encode all categories of retinal _____ (zero, crossed (near), and uncrossed (far)).

Answer 25

Disparity

Question 26

Binocular neurons in V1 perceiving depth within ____ _____ area.

Answer 26

Panum’s fusional

Question 27

Neurons with a 0 disparity preference

Answer 27

No difference between retinal image of left and right eye, its firing rate will increase when there is NO disparity - most neurons have this disparity tunning

Question 28

Tuned near neurons prefer...

Answer 28

A little crossed disparity

Question 29

Tuned far neurons prefer...

Answer 29

A little uncrossed disparity

Question 30

Far neurons prefer

Answer 30

Uncrossed disparity

Question 31

Near neurons prefer

Answer 31

Crossed disparity

Question 32

There is a gradual decrease of perception away from the ______

Answer 32

Horopter

Question 33

Stereoscope

Answer 33

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

Question 34

For movies to appear 3D, each eye must receive a slightly different ____

Answer 34

View

Question 35

“anaglyphic” glasses

Answer 35

Red lens for one eye, blue for the other - Used for early 3D movies

Question 36

Current methods for 3D glasses

Answer 36

- Polarized light and polarizing glasses to ensure that each eye sees a slightly different image Polarized light = each image is the same color, but the polarity (orientation of light wave) differs

Question 37

Correspondence problem

Answer 37

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

Question 38

2 hypotheses of object integration

Answer 38

1. Our visual system perceives the object before integrating it in each eye and send this information forward to combine the images 2. The visual system is made so that image from each eye is automatically integrated before recognizing the object

Question 39

Random dot stereogram

Answer 39

- Visual pattern consisting of two images made up of random dots. - When viewed with both eyes (using stereoscopic vision), the two images create the illusion of a three-dimensional shape or object floating in space.

Question 40

Generation of a random dot stereogram

Answer 40

1. 2 similar random-dot patterns are created. 2. A section of 1pattern is shifted slightly horizontally (left or right) relative to the corresponding section in the other pattern.

Question 41

Disparity in a random dot stereogram

Answer 41

1.The horizontal shift creates binocular disparity when the two images are viewed together. 2.This disparity mimics the differences in the images seen by the left and right eyes in real-world 3D viewing.

Question 42

Perception of a random dot stereogram

Answer 42

1.When each eye views one image (e.g., using a stereoscope or by crossing/uncrossing the eyes), the brain fuses the two patterns. 2.The shifted section appears as a 3D object or surface due to the brain's interpretation of the disparity.

Question 43

If the square from the left eye view is to the right of the square in the right eye view, there will be _____uncrossed/crossed disparity

Answer 43

Crossed (objects seen as more near)

Question 44

If the right square is to the right of the square of the left eye view, there will be _____uncrossed/crossed disparity

Answer 44

Uncrossed (object seen as more far)

Question 45

Binocular rivalry

Answer 45

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

Question 46

Most time there is no double vision for objects outside panum fusional area, because...

Answer 46

The visual system supresses the image that is coming from one of the eye for a couple of seconds, then switches to the other side (binocular rivalry)

Question 47

Right object recognition hypothesis

Answer 47

We cannot recognize certain stimuli with only 1 eye, so it is the 2nd hypothesis : The visual system is made so that image from each eye is automatically integrated before recognizing the object