Unit 9

Question 1

How do we perceive depth?

Answer 1

by using information from:
- the environment
- physical sensations

Question 2

What is one of the most widely known approaches to the question as to how we perceive 2d images as 3d?

Answer 2

The cue approach

Question 3

What is the cue approach?

Answer 3

study of information in retinal image that provides cues regarding depth

Question 4

What are the three main types of visual cues?

Answer 4

Oculomotor
Monocular
Binocular

Question 5

Oculomotor cues

Answer 5

information we can feel because of eye movements:
- convergence
- accommodation

Question 6

Convergence

Answer 6

inward movement of eyes when looking at nearby objects
-> causes change in convergence angle
movement produces physical sensation
-> used by NS to calculate distance

Question 7

Accomodation

Answer 7

Change in shape of lens to focus on objects at various distances

Question 8

Ciliary muscles

Answer 8

muscles that change shape of lens
Tension caused by ciliary muscles used to calculate distance

Question 9

What are oculomotor cues useful for?

Answer 9

Visual information of up to an arms length

Question 10

What is more useful? Convergence or accomodation?

Answer 10

Convergence (usually), as it produces a stronger physical sensation

Question 11

Monocular cues

Answer 11

depth information from just one eye
consist of:
Accommodation
Pictorial cues
Motion cues

Question 12

Occlusion

Answer 12

When an object in a scene hides another one
partially obstructed object perceived as further away
-> only gives relative distance

Question 13

Relative height

Answer 13

Objects higher in visual field generally perceived as further away
-> however depends on horizon
-> for objects above horizon opposite effect

Question 14

Familiar size

Answer 14

Using prior knowledge of size of objects to judge distance
most useful when other information about depth isn’t available

Question 15

Relative size

Answer 15

when we know that that two objects are of same size but presented as different size
-> located at different distances
-> objects further away will occupy less visual space

Question 16

Perspective convergence

Answer 16

converging lines towards a point in a 2D image
-> objects closer to the point are further away

Question 17

Atmospheric perspective

Answer 17

The further an object is away, the greater the number of dust, water and air particles between us and the object
-> if object in 2D image less sharp (often with blueish colour)
-> appears further away

Question 18

Why does the blueish colour occur for far away objects?

Answer 18

blue light scatters off of particles easier than other colours of visible light

Question 19

Texture gradient

Answer 19

When objects in environment are equally spaced apart
-> produce perception of texture
-> objects less spaced: further away
-> objects more spaced: closer
=> change in texture: texture gradient

Question 20

Shadows

Answer 20

Decrease in light sensitivity because of the obstruction of light
Give information about three-dimensional shape of objects

Question 21

Motion cues

Answer 21

monocular cues that rely on movement to perceive depth

Question 22

Motion parallax

Answer 22

when moving by objects:
- going slower appear more distant
- going faster appear closer

Question 23

Why does motion parallax occur?

Answer 23

images of close and distant objects move across retina at different speeds

Question 24

Deletion and accretion

Answer 24

some objects cover others (deletion)
some objects get covered (accretion)

Question 25

What does the utility of monocular cues depend on?

Answer 25

situation distance

Question 26

Binocular cues

Answer 26

take differences between images created in left and right eye into account

Question 27

What is the difference in images called?

Answer 27

binocular disparity

Question 28

What is stereoscopic depth perception?

Answer 28

basis: binocular disparity easily seen in cinemas 3D movies use two different angles -> 3d glasses help separate two images

Question 29

What is the binding problem?

Answer 29

How do we combine individual characteristics to perceive whole object?

Question 30

Feature integration theory

Answer 30

Treisman & Gelade attempts to answer binding problem -> 2 stages of object recognition

Question 31

2 stages of object recognition

Answer 31

1 Preattentive stage (feature search): individual characteristics independently and automatically detected 2 focused attention stage(conjunction): FA used to combine individual features

Question 32

How did Treisman & Schmidt find evidence to support the Feature integration theory (FIT)?

Answer 32

illusory conjunctions participants shown shapes and numbers (–200ms) needed to say numbers before shapes -> individual feature detection not influenced -> conjunction impaired: couldn't correctly combine colours and features since FA was disrupted

Question 33

Recognition-by-components theory

Answer 33

Biederman geons (simple geometric shapes) aid in object recognition recognition of objects by dividing them into geons

Question 34

What is a fundamental assumption of the recognition-by-components theory?

Answer 34

viewpoint invariance geons equally recognisable from every angle -> also applies to objects constructed from geons

Question 35

What is the issue with the recognition-by-components theory?

Answer 35

doesn't explain how we recognise specific faces should cause same neurone activation for viewpoint invariant geons but doesnt (only some in inferior temporal cortex)

Question 36

What is one of the most prominent theories as to how we recognise objects

Answer 36

Prototype theory we recognise objects and compare them with object that best represents category -> prototype

Question 37

What is a prototype?

Answer 37

averaged model of all previously encountered objects for a categroy

Question 38

What is typicality?

Answer 38

the degree to which variations represent the prototype -> high typicality = high similarity with prototype

Question 39

How did Rosch quantify typicality?

Answer 39

showed participants series of photos had to rank from 1-7 which photo best represented the category

Question 40

How did Rosch & Mervis demonstrate typicality?

Answer 40

had to name characteristics of multiple objects -> different objects of a category show high family resemblance => link between typicality and family resemblance

Question 41

How do we organise categories of objects to take into account more specific differences in characteristics between objects?

Answer 41

organising them into hierarchical structures

Question 42

The three levels in hierarchy of object recognition

Answer 42

Global (Superordinate) Basic Specific

Question 43

Which is the most psychologically important?

Answer 43

The basic level ->majority of people use it to rapidly recognise an object

Question 44

How did Rosch et al. prove the preference for the basic level using family resemblance?

Answer 44

list features of: - furniture -> 3 features - table -> 9 features - kitchen table -> 10.3 features => demonstrates usefulness of basic level

Question 45

What else shows the more useful nature if the basic over the specific level?

Answer 45

Two objects of the basic level have less similarities that two objects at specific level

Question 46

What does the basic level depend on?

Answer 46

experience