Lecture 2- Illusions

Question 1

What are the steps of information processing?

Answer 1

Converting outside world into internal events through encoding

Question 2

What are the different levels of grey that humans can discriminate?

Answer 2

5000

Question 3

What do illusions have a role in?

Answer 3

The study of sensory systems for illusion depth

Question 4

What are the specific properties of an image?

Answer 4

Specific aspects such as spatial and visual, two dimensions, static

Question 5

What are the basic properties of an image?

Answer 5

Brightness, colour and patterns

Question 6

What is black and white?

Answer 6

The amount of light which interprets the visual system as measurement

Question 7

What is colour?

Answer 7

A small number of linguistic categories

Question 8

What did Berlin and May find?

Answer 8

Different number of colour names in different cultures

Question 9

What is perpetual colour space?

Answer 9

How colours are arranged

Question 10

How is the colour circle arranged?

Answer 10

According to similarity

Question 11

What did 3M different colour measure?

Answer 11

Discrimination threshold

Question 12

What is brightness contrast illusion?

Answer 12

The perceived brightness of an object being effected by the brightness of the surroundings

Question 13

Why does the brightness contrast illusion occur?

Answer 13

Due to the way the visual system processes and compares the different light levels

Question 14

What is an example of the brightness contrast illusion?

Answer 14

Simultaneous contrast effect

Question 15

What is simultaneous contrast effect?

Answer 15

When a light object is placed against a dark background it appears brighter than when placed in a background of equal luminance

Question 16

What does filters do in the visual stream for contrast?

Answer 16

Subtract stimulus intensity in the surround reigion to form lightness in the centre

Question 17

What is contrast?

Answer 17

A perceptual measure not being absolute but the relative stimulus intensity in comparison to the surround

Question 18

How is the outside world represented?

Answer 18

In retinotopic maps of neurones with the centre-surround receptive fields

Question 19

What reduces redundancy?

Answer 19

Image compression

Question 20

What is an example of a visual illusion?

Answer 20

Hermann grid

Question 21

What happens in Hermann grids?

Answer 21

The grey spots are believed to be the result of opponency filtering

Question 22

What is opponency filters?

Answer 22

Contrast enhancement when there is excitation-inhibition

Question 23

What happens to spatial filters with opponcency receptive fields?

Answer 23

Enhance the contrast and reduce the redundancy

Question 24

What happens inside black square for Hermann grids?

Answer 24

There is no stimulation of excitatory centre and inhibition that surrounds so overall excitation and a perception of darkness

Question 25

What happens in white bars for Hermann grids?

Answer 25

Small parts of inhibitory surrounds are stimulated, excitation will dominates inhibition giving the perception of brightness

Question 26

What happens at white intersections for Hermann grids?

Answer 26

Larger parts of inhibitory surrounds are stimulated so there is a small overall excitation so there is a reduction of brightness

Question 27

What is real motion?

Answer 27

Perceived when an object is changing location in space and time

Question 28

What is contrast illusion?

Answer 28

The enhancement of colour differences in space when presented next to each other

Question 29

What is the Munker-White effect?

Answer 29

Assimilation of colour and a higher level colour interaction

Question 30

What are after images?

Answer 30

The consequence of an illusion after long exposure to a stimulus followed by a sudden change

Question 31

What is the third dimension reconstructed by?

Answer 31

Flat images that captures the eyes

Question 32

What are the cues for third dimension?

Answer 32

Using two eyes, motion parallax, contrast, texture, size and perspective

Question 33

What are pictorial cues?

Answer 33

A range of depth information being extracted from a static monocular image

Question 34

What is binocular in depth cues?

Answer 34

Extending the visual field when there is a combination of information from 2 eyes allowing precise depth measurment through stereopsis

Question 35

What is stereopsis?

Answer 35

A perception of depth produced in the brain from both eyes seeing visual stimuli

Question 36

How does stereopsis work?

Answer 36

Retinal projection of the object on opposite sides of the fovea indication depth relative to the plane of fixation

Question 37

What does stereopsis produce?

Answer 37

Depth impressions in projected/printed images

Question 38

What are the cues for depth perception?

Answer 38

Geometric perspective, texture, occlusion and binocular disparity

Question 39

What is size constancy effect?

Answer 39

The basis of the Ponzo illusion

Question 40

What is the Ames room?

Answer 40

How the size of objects are perceived to be distorted because the misleading geometry generates an incorrect frame of reference

Question 41

What are examples of colour illusions?

Answer 41

Colour effect and simultaneous colour contrast

Question 42

What are not colour illusions?

Answer 42

Kanizsa triangle and red green colour blindness

Question 43

What are the proximities in motion correspondence problems?

Answer 43

Vertical and horizontal proximity

Question 44

What is the after effect of motion illusion?

Answer 44

The perceiced explanation of the stripe pattern is an illusion in itself

Question 45

What are the key readings for illusions?

Answer 45

Jameson and Hurvich + White

Question 46

What does Jameson and Hurvich say about brightness and colour vision

Answer 46

They are important aspects for visual perception and visual theory

Question 47

What does Jameson and Hurvich say about adaptation?

Answer 47

It is an adjustment in sensitivity

Question 48

What does Jameson and Hurvich say about sensitivities?

Answer 48

They change depending on inverse proportion to excitation when the visual system is exposed

Question 49

What does Jameson and Hurvich say about the luminance of the test field?

Answer 49

When it increases the luminance of the surround should increase in the same proportions for a brightness match

Question 50

What does White say about the effect of illusions?

Answer 50

It is stronger at high spatial frequencies

Question 51

What does White say about the effect of pattern on perceived brightness?

Answer 51

It is lightness contrast and lightness assimilation

Question 52

What does White say about the explanation of lightness contrast?

Answer 52

It is the lateral inhibition between retinal units