L3 Depth Perception and Binocular Vision

Question 1

What are the two types of depth perception cues that humans use?

Answer 1

Binocular and Monocular

Question 2

What are the 2 pictorial cues to depth?

Answer 2

Occlusion

Size Constancy

Question 3

What does occlusion tell us about?

Answer 3

Depth ordering and what is closer to you

Question 4

What does size constancy tell us?

Answer 4

We understand how big an object should be and use that to determine depth

Question 5

Where is our depth perception greatest?

Answer 5

In peripersonal space (50-100cm in front of us)

Question 6

What cue is Ames room exploiting?

Answer 6

Size constancy

The room looks to be normal and yet one girl is much bigger than the other, in reality, the room is on an angle and is designed so it looks the same so this tricks our brain into seeing one girl bigger than the other.

Question 7

Occlusion and Size constancy can be referred to as pictorial cues but can also be referred to as _____ cues

Answer 7

Contextual

• They give context to the object we are looking at*
• What is expected in the environment (a more probable event) can influence perception*

Question 8

Are occlusion and size constancy monocular cues or binocular cues

Answer 8

Monocular

Question 9

What is a monocular cue for depth perception?

Answer 9

The depth of an object can be estimated with only one eye view

Question 10

What is Motion Parallax?

Answer 10

The relative motion that is created when we or objects in our environment move.

Question 11

Why is Motion Parallax a depth cue?

Answer 11

Close objects move most, far objects move the least

Question 12

What is binocular vision?

Answer 12

Vision with two eyes

Question 13

What are the three binocular vision cues?

Answer 13

Vergence

Binocular disparity

Accommodation

Question 14

How do binocular cues to depth work?

Answer 14

Binocular cues to depth require information to be combined from the two eyes.

Question 15

What is binocular disparity?

Answer 15

The difference in the left and right eye in what you can see in relation to the horopter

Question 16

Why do prey animals have eyes on the sides of their heads?

Answer 16

They need to be aware of predators more than they need to be able to focus intently on whats in front of them so they need a larger field of view (FOV).

Question 17

What is the interpupillary (distance between the pupils of each eye) distance for humans on average?

Answer 17

57mm

Question 18

What is the line called where our vision is neither crossed or uncrossed in terms of binocular disparity?

Answer 18

Horopter

Question 19

What is retinal disparity?

Answer 19

The way that your left eye and your right eye view slightly different images

Question 20

What does dichoptic mean?

Answer 20

Viewing a separate and independent field by each eye.

Question 21

Are thresholds for disparity (stereo) judgements comparable to width judgements?

Answer 21

Yes

It looks like there is a constant i.e. there is a law in play here

Question 22

What does it suggest for what is happening in the brain that disparity and width judgements are similar?

Answer 22

Suggests that the brain is using a similar ‘code’ to judge the position of two locations in space

Question 23

Biocular disparity and monocular cues can cues to judge depth.

What is the third cue?

Answer 23

Sensorimotor cues

Question 24

What are the two types of sensorimotor cues?

Answer 24

Accommodation

Vergence

Question 25

What is accommodation?

Answer 25

How the lens is stretched or relaxed to bring a target into focus

Question 26

How is accommodation a depth cue?

Answer 26

Strain on the lens is sensed by the visual system and can be used to calculate the distance of an object.

Question 27

In **accommodation**, which muscles pull or push the lens which allows us to focus light on the back of the retina?

Answer 27

Ciliary muscles

Question 28

As people age, the lens in the eye becomes less flexible. Accommodation changes and it is harder to change...

Answer 28

focal length

Question 29

What happens to the lens in our eyes as we age?

Answer 29

The lens becomes less flexible and this makes it harder to change focal length.

Question 30

What is a **hyperopic eye**? How is it fixed?

Answer 30

Fixation plane is beyond the retina Contact Lens

Question 31

What is a **myopic eye**? How is it fixed?

Answer 31

The focal plane is too far in front of the retina Fixed with a concave lens

Question 32

What is (con)**vergence**?

Answer 32

Angle of gaze of two eyes * Eyes can be turned towards each other, or turned outwards* * (controlled by ocular muscles)*

Question 33

What does convergence allow us to do?

Answer 33

Allows us to change focal distance

Question 34

What is **Strabismus** (strabismic amblyopia)?

Answer 34

A deficit in vision due to the misalignment of one eye - often caused by different muscle tension in each eye

Question 35

What is the term for an outward pointed eye?

Answer 35

**Exotrope**

Question 36

What is the term for an inward pointed eye?

Answer 36

**Esotrope**

Question 37

How is Strabismus treated?

Answer 37

With early surgery

Question 38

What happens if you do not treat Strabismus early and miss the critical period?

Answer 38

Strabismus makes you lose contrast sensitivity and you have a lack of depth perception. You may permanently lose some of these depth cues if not treated in the critical period.

Question 39

What is stereo (stereoscopic) vision?

Answer 39

The human ability to view with both eyes in similar but slightly different ways. ## Footnote *Another word for binocular*

Question 40

What is stereo vision primarily good for?

Answer 40

Fine Motor Skills *e.g. surgery, picking berries, playing music*

Question 41

What can we use to simulate depth (i.e. virtual reality and 3d movies)

Answer 41

Binocular Disparity ## Footnote *different left and right eye view to give the illusion of depth*

Question 42

What are two limitations for using disparity information for virtual reality/augmented reality?

Answer 42

1. 30-40% of people have compromised stereo vision 2. We only have high-resolution vision at the point we look at * The distance we focus at is linked to the distance the two eyes are pointing at. AR/VR requires different distances for these things* * Can give us headaches and other issues if we use VR for too long as a result*