Depth, Size And Illusions Flashcards

1
Q

We perceive…

A

A 3D world but the image on our retina is 2D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Cues

A

Use cues to extract depth info
Cues are info in the retinal image that’s correlated with depth
Across our lives we learn to associate cues with depth
Associations become automatic through repeated exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens to the image on the retina

A

The image on the retina is upside down. Perception flips it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

3 broad cues

A

Bits of info that are:

1: oculomotor = minds get from muscles around eye (sensing position of eyes)
2: monocluar= extracted from images by either eye independently
3: binocular = extracted from images by both eyes working together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Ocular convergence

A

Oculomotor Cue

Inward movement of eyes and the corresponding muscle tension when focusing on near objects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Lens accomodation

A

Oculomotor cue where tension is detected in the ciliary muscles
Accomodation is the change in lens shape when focusing on near or far objects
Far = relaxes
Close = contacts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Monocular cues are mostly

A

Pictorial cues - information extracted from 2D images

Also non-pictorial cues - info cannot be extracted from static 2D image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Occlusion

A

When an object partially covers another

Object that is occluded is usually deeper in the visual field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Relative height

A

Looking below horizon = objects higher are more distant

Looking above horizon = objects lower are more distant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Relative size

A

When objects are equal size, the closer ones will take up more of your visual field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Perspective convergence

A

Parallel lines appear to approach each other at greater distances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Perspective convergence in art

A

European art- effect loss in middle ages and reemerged in Renaissance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Familiar size

A

Knowledge of familiar objects can help us infer which objects are closer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Atmospheric perspective

A

Distant objects are blurrier and can have blue/grey tint

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Texture gradient

A

Equally spaced elements are more closely packed as distance increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Shadow

A

Position of objects shadow can be helpful to perceive depth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Cues combined

A

Cues are more useful when they give consistent info

18
Q

Motion parallax

A

Non-pictorial monocular cue

Near objects glide rapidly past and far objects move slowly

19
Q

Occlusion via movement

A

Non-pictorial cue
Objects are covered and uncovered as we move relative to them
Covering = deletion
Uncovering = accretion

20
Q

Binocular cues involve

A

Comparing the slightly different views presented in each eye

21
Q

Binocular disparity

A

Disparity between different images created by objects falling in different locations on the retina

22
Q

Corresponding points

A

The forea is always the corresponding point as whatever is focused on falls on the same spot on both retinas

23
Q

Horopter

A

Unfocused things fall on the corresponding point if they are on the an arc called the horopter
Images not on the horopter fall on non-corresponding points

24
Q

Crossed disparity

A

Crossed: object inside horopter = appears closer
Uncrossed: object outside horopter= appears further

25
Stereoscopes
Take advantages of binocular disparity to create depth in a pair of 2d images
26
Chromostereopsis
See red circle in front of blue Some see no differences and minority reverse Effect reverses on white background From slightly different refractions of light from colours = non-corresponding points on eye
27
Corresponding problem
How does our visual system combine images | Potentially from specific features of objects but this doesn't explain objects like random-dot stereograms
28
Depth perception other species
Animals use same eves as humans But binocular disparity requires front facing eyes for overlapping fields of view Predators tend to have front facing Prey tend to have side facing (lateral)
29
Environmental cues to size
Size and depth perception are interrelated | Size is a cue for depth and depth is a cue for size
30
Retinal image size
Visual angle is the amount of the retina that an image occupies Far away = smaller image = less angle Close = big image = greater angle Your thumb at arms length covers 2 degrees of visual angle When depth cues are absent, perceived size determined by retinal image size eg- moon and sun have almost same visual angle but moons bigger so it covers sun during eclipse
31
Removing depth cues
With depth cues provided judgements were based on physical size With depth cues removed judgements were based on the size of the retinal image eg the visual angle
32
Size constancy
Perception that objects size is relatively constant even if the size of retinal image changes Expressed in the size-distance scaling equation Brains have no control over visual angle but try to keep perceived size of object the same Eg visual angle goes up distance from object must go down
33
Emmert's law
Retinal size of an after image stays constant Perceived size changes with distance Closer afterimage = smaller it seems (follows size- distance scale)
34
Nonveridical perception
Occurs during visual illusions | Stimulus dimensions that are only subjectively perceived to be there
35
Muller-lyer illusion
Arrows with different faces fins - shorter arrows have inward fins Explanation: size constancy misapplied to 2D Perceive fins as belonging to objects pointing If an objects coming towards us its closer = smaller
36
Miller-lyer problems with size constancy
``` Dumbbell version (no fins but circles) = same perception Also occurs in 3D images that don't implicate depth (things at the same distance but spread apart) ```
37
Conflicting cues muller-lyer
Perception depends on: 1: actual length of lines 2: overall length of figure Conflicting cues are integrated into a compromised perception of length
38
Ponzo illusion
Horizontal objects placed over train tracks Upper object seems longer but same size Misapplied Size constancy
39
Ames room
Room constructed to look normal with one eye view Left corner is actual further away Explanations: 1 - size-distance scaling: person on left has smaller retinal image + perceived distance is the same = perceived size must be smaller 2- relative size: size perception is relative to other objects (filling whole room)
40
Moon illusion
Moon appears larger on the horizon Explanations: 1 - apparent depth theory: horizon is surrounded by other depth cues 2- hastened heavens theory: horizon is perceived as further away than sky = small retinal image size larger on horizon
41
Forced perspective
When photos remove depth cues to change the size of people | Leaning tower of Pisa where people look like they're holding it