Chapter 10 - Lecture Section 10.3

Question 1

Why must Perceived Depth and Size of objects be codependent?

Answer 1

Because of what’s referred to as the Visual Angle. In order to get a sense of size from the visual angle of the retinal image, we have to have information about depth, that is why the two factors are codependent.

Question 2

How can two objects of different sizes take up the same Visual Angle?

Answer 2

If the two objects are at different distances, like if you have a larger but more distant object, it can take up the same visual angle, anything that’s within the arc would take up the same visual angle

Question 3

How can we easily approximate the Visual Angle of different objects in our environment?

Answer 3

By looking at the width of your thumb at arm’s length, it’s about 2 degrees of Visual Angle.

Question 4

For equal Visual Angles: If those items are perceived at the same distance and have the same Visual Angle, then they must be ___ size.

Answer 4

the same

Question 5

For equal Visual Angles: If one is perceived as farther away, then it must be ___ than the other.

Answer 5

larger

Question 6

What is Size Constancy?

Answer 6

Occurs when the size of an object is perceived to remain the same even when it is viewed from different distances. This is similar to Colour Constancy and Brightness Constancy

Question 7

Depending on whether an apple is in front of us on our desk, or on the other side of the room, we are able to estimate its size pretty accurately, why is this?

Answer 7

Size Constancy and the Size-Distance Scaling Mechanism

Question 8

Humans use Size-Distance Scaling to achieve ___.

Answer 8

Perceptual Size Constancy

Question 9

What is the formula used for the Size-Distance Scaling Mechanism used for Perceptual Size Constancy?

Answer 9

Perceived Size = Constant (Retinal image size x Perceived Distance)

Question 10

Perceived Size and the Perceived Distance are both affected by ___.

Answer 10

depth cues

Question 11

We must take into account the Visual Angle to get the ___, which is an easily quantifiable and measurable objective reality.

Answer 11

Retinal image size

Question 12

The Retinal image size is the geometrical description of how big the image is on the Retina in terms of ___.

Answer 12

Visual Angle

Question 13

What is Emmert’s Law?

Answer 13

The farther away an Afterimage appears, the larger its size

Question 14

What is the use of Emmert’s Law?

Answer 14

Emmert’s Law provides a great example of how we can use the Size-Distance Scaling Mechanism dynamically.

Question 15

What can cause the percept of the size to change?

Answer 15

The perceived distance

Question 16

When participating in an illusion the Afterimage should appear quite small when looking at your hand, and when looking over to the distant wall, that Afterimage is much larger, why is this?

Answer 16

The Afterimage is related to the Photoreceptors on the Retina that are bleached, so it provides a measure of the Visual Angle of that Retinal image.

The perceived distance is causing the percept of the size to change

Question 17

When looking at the Afterimage on your hand, you perceive the distance from your eye to your hand, the close object, as being ___.

Answer 17

short

Question 18

When looking at the Afterimage on the wall, you perceive the distance, using all those depth cues, to the wall, as being ___.

Answer 18

very far

Question 19

In an Afterimage, the Retinal image size will be ___.

Answer 19

constant

Question 20

When the Afterimage is on the hand, the perceived distance from you is ___, and so, a Constant x a small number will be a ___ number.

Answer 20

small // small

Question 21

When the Afterimage is on a distant wall, the perceived distance is ___, so a constant x a large number turns into a ___ number.

Answer 21

large // large

Question 22

Without depth cues, ___ can be misinterpreted.

Answer 22

size

Question 23

Whiteout condition Helicopter scenario: If what the pilot assumes is the perceived size of the object as large, we’re having a ___ number divided by a constant which will be a large number, so the pilot thinks that they are fairly ___ the ground and are ___.

Answer 23

large // high off // safe

Question 24

Whiteout condition Helicopter scenario: The Retinal image size is ___ because it’s taking up the box, the same ___.

Answer 24

constant // visual angle

Question 25

Whiteout condition Helicopter scenario: As the pilot approaches the object, they see that it’s not a truck, it’s a box. Now we have the perceived box is small, divided by a constant which produces a ___ number. Their perceived distance from the object, and therefore the ground, is much ___, and they are ___.

Answer 25

small // smaller // not safe

Question 26

Size perception is fairly accurate when you have ___.

Answer 26

depth cues

Question 27

Size perception is inaccurate and merely reflects visual angle when you lose the ___.

Answer 27

depth cues

Question 28

The Moon is much smaller than the Sun, so why do they appear to us as the same size?

Answer 28

They appear to be the same size because the Moon is much closer than the Sun is. Both the Sun and Moon have the same visual angle, and take up about 0.5 degrees of visual angle.

Question 29

What depth cues can help provide additional size information?

Answer 29

Relative Size and Familiar Texture

Question 30

How can Relative Size help provide additional size information?

Answer 30

You use familiar objects that act as a yardstick for unfamiliar objects.

Example: We see an image of a chair, and we assume it’s a normal chair based on what we already know about chairs. Then in the next image, we see a person standing next to it, and the chair towers over the person, leading us to realize its a large sculpture of a chair. We used the person as the familiar object, and the person rescaled the true size of the chair.

Question 31

How can Familiar Texture help provide additional size information?

Answer 31

If you’re standing on the cobblestone, so that you can see the size of your foot as you’re standing on them, then you have a good estimate of how big the cans are when they are several distances away from you, because you know the size of a cobblestone, and you know that this object takes up a width of a cobblestone, and so that allows you to get a good size estimate of those objects, even if they are unfamiliar.

Question 32

What is Veridical Perception?

Answer 32

Perception that matches the actual physical stimulus

Question 33

In well-lit natural environments, human depth and size perception is very close to ___.

Answer 33

Veridical

Question 34

When we have Magnitude Estimation, there is a ___ relationship between the size of the stimulus and our estimate of that stimulus size.

Answer 34

linear

Question 35

Muller-Lyer Illusion causes ___ perception.

Answer 35

non-veridical

Question 36

The Muller-Lyer Illusion causes ___ perception.

Answer 36

non-veridical

Question 37

What is the Muller-Lyer Illusion?

Answer 37

You are asked to concentrate on the straight vertical segment, and asked which straight vertical lines is longer, most people report that the second line is longer, however, it is an illusion, and both lines are the same length.

Question 38

In the Muller-Lyer Illusion which line is longer?

Answer 38

It is an illusion, and both lines are the same length.

Question 39

What is one explanation for the Muller-Lyer Illusion?

Answer 39

Misapplied Size Constancy Scaling

Question 40

The Muller-Lyer Illusion, Misapplied Size Constancy Scaling: The top fin projection looks like the ___ corner of a building, and inside corners are often ___ from us, so it the same visual angle, but the distance is larger, so we perceive the size of this line as ___.

Answer 40

inside // further away // larger

Question 41

The Muller-Lyer Illusion, Misapplied Size Constancy Scaling: The bottom fin projection lines pulled inwards resembles the ___ corner of a building, where we often approach these outside corners. And so therefore we assume that it is ___, so the viewing distance is closer, smaller number, retinal image size is constant, constant times a small number equals a ___ perceived size of that line.

Answer 41

outside // closer // smaller

Question 42

Why does the Misapplied Size Constancy Scaling for The Muller-Lyer Illusion not hold up?

Answer 42

Because the barbell version contains circles instead of lines making corners, but creates the same illusion of one line looking longer than the other when they are the same length.

Question 43

What are the two pieces of information taken into account when using the Conflicting Cues Theory to explain the Muller-Lyer Illusion?

Answer 43

They take into account the size of the component, which you are directing their attention to, so the lines, but they also take into account the overall size of the figure.

Question 44

How does the Conflicting Cues Theory explain both the versions of the Muller-Lyer Illusion?

Answer 44

The overall size of the figure contaminates their judgement of the component, and so because the overall image of one is larger, that largeness contaminates their perception of the component within the figure.

Question 45

The Ponzo Illusion

causes ___ perception.

Answer 45

non-Veridical

Question 46

In The Ponzo Illusion, the ___ monster appears much larger, but the size of the monsters, in terms of visual angle, is ___.

Answer 46

distant // identical

Question 47

In the Ponzo Illusion, the marmot at the top of the image looks ___, but they are taking up ___ visual angle.

Answer 47

larger // an identical

Question 48

In the Ponzo Illusion, how do we know the marmot at the top of the image is further away than the marmot that is closer?

Answer 48

By using depth cues like Perspective Convergence and the texture of the gravel and railway ties.

Question 49

In the Ponzo Illusion, if we use the Size-Distance Scaling Mechanism, we have a ___, but for the marmot at the top of the screen, there is a ___ perceived depth, so a constant x a large number becomes a large perceived size.

Answer 49

constant retinal image size // larger

Question 50

In the Ponzo Illusion, for the marmot at the bottom of the image, there is a ___ perceived depth, or distance away, we have a constant x a small number and that produces a ___ perceived size.

Answer 50

small // small

Question 51

What is an Ames Room?

Answer 51

The Ames room is designed so that the Monocular depth cues give the illusion that both corners of the back wall are the same distance away from you, but they aren’t.

Question 52

What are important aspects of the Ames Room?

Answer 52

consistent textural information and monocular vision

Question 53

What were the problems with the Halifax Discovery Center Ames room?

Answer 53

The floors were scuffed which ruined the textural cue, and they allowed a large window for you to look through with both eyes, Binocular, so you could use Stereopsis which ruined the illusion.

Question 54

In an Ames Room, the perceived distance from the observer is gonna be ___ between the two corners of the room.

Answer 54

constant

Question 55

In an Ames Room, the observer misperceives the size of the person closest to them as being ___.

Answer 55

larger

Question 56

What is the Moon Illusion?

Answer 56

The horizon Moon appears much larger than the apex Moon, so when the Moon is closer to the ground it seems larger, and when it’s up high in the sky it seems smaller.

Some people believe that the moon is on an elliptical path and that it’s closer to the earth when it’s on the horizon, but that’s not true.

The moon does not change size, but we perceive that it does.

Question 57

What is the Apparent Distance Theory (Flattened Heavens Theory) for the Moon Illusion?

Answer 57

This explains that we perceive the moon at different distances, and that leads us to use our Size-Distance Scaling Mechanism to then perceive the moon at different sizes.

Question 58

In the Apparent Distance Theory (Flattened Heavens Theory) the Moon takes up a Constant visual angle, so the size of the Retinal image is Constant between the two conditions.

A smaller distance, so a contestant x a small distance = a ___ perceived size, here, with this larger assumed distance, we have a constant x a large number = a ___ perceived size.

Answer 58

small // large

Question 59

In the Apparent Distance Theory (Flattened Heavens Theory) the horizon Moon is perceived as farther away, and therefore ___.

The elevated Moon is perceived as closer, and therefore ___.

Answer 59

larger (many depth cues from terrain and surface objects) // smaller (few depth cues)

Question 60

What is the problem with the Apparent Distance Theory (Flattened Heavens Theory)?

Answer 60

This works only if you perceive the moon as being flat and kind of pasted onto the night sky, and some people object to this explanation because they don’t perceive the Moon as being pasted on flat onto the night sky, they perceive it as floating in front of the night sky, and so it doesn’t matter if they perceive the night sky at horizons to be further away and at the apex to be closer, because the moon is not at the same depth as the night sky, its closer.

Question 61

What is the Angular-Size Contrast Theory?

Answer 61

The contrast in size between the Moon and surrounding objects creates this illusion that the Moon is bigger at the horizon.

Question 62

In the Angular-Size Contrast Theory, the Moon appears ___ when it’s surrounded by large objects, and it appears ___ when it’s surrounded by small objects.

Answer 62

smaller // bigger

Question 63

How do we make the Angular-Size Contrast Theory work to make the Horizon Moon look bigger?

Answer 63

Look at the horizon moon, there are all these tiny little features on the horizon (skyline of anything from buildings or trees or mountains) and this constant size moon, and so this appears larger compared to these small objects.

Question 64

How do we make the Angular-Size Contrast Theory work to make the Apex Moon look smaller?

Answer 64

In the sky we essentially have to ignore the small features like stars, and say that the moon sitting on this big empty expansive sky is a constant surrounded by a big expanse and so it will look small.

Question 65

The Angular-Size Contrast Theory is closely related to the ___ Illusion.

Answer 65

Ebbinghaus

Question 66

The Angular-Size Contrast Theory explanation for the Moon Illusion requires some assumptions that are slightly different than the Flattened Heavens explanation for the moon illusion, and perhaps the truth ___ between people.

Answer 66

varies