lecture 6

Question 1

how is the image we receive from the real world different to our perception?

Answer 1

image we receive is 2D but our perception is 3D

Question 2

generally people are quite accurate at judging an ambient distance up to…?

Answer 2

20 feet

Question 3

Visual cliff experiment

Answer 3

36 babies
plexiform platform with illusory cliff on one side

no babies coaxed to their mothers when it meant movement from the shallow end across the deep end

all babies coaxed to mothers when they could stay on shallow end

Question 4

conclusion of the visual cliff experiment

Answer 4

depth perception is partially innate, but develops further when a baby starts crawling etc

Question 5

cues to depth

Answer 5

oculomotor cues
pictorial cues (monocular cues)
motion produced cues
binocular disparity

Question 6

basis of oculomotor cues

Answer 6

cues that depend on our ability to sense the position of our eyes and the tension in our eye muscles

Question 7

what happens as an object moves closer to our eyes?

Answer 7

our eyes move inwards and the tension in them increases

Question 8

convergence

Answer 8

eye muscle cause you to look inwards (closer teh object the smaller the convergence

Question 9

accommodation

Answer 9

as the lens bulges to focus on a near object

tightening of the ciliary muscles, allowing the pliable crystalline lens to become more rounded

Question 10

what distances produce effective oculomotor cues

Answer 10

only closer that 5-10 feet

Question 11

what are shape of the lens and position of the eye correlated with?

Answer 11

the distance of the object you are observing

Question 12

what are pictorial cues?

Answer 12

cues that can be depicted in a still picture (TV, photos, paintings) and do not require viewing with both eyes in order to work

Question 13

8 pictorial cues

Answer 13

1) overlap, interposition or occlusion
2) relative size
3) relative height
4) atmospheric perspective
5) familiar size
6) linear perspective
7) shading and shadows
8) texture gradient

Question 14

overlap, interposition or occlusion

Answer 14

one object obscures part of another, or overlaps with it

Question 15

relative size:

Answer 15

the retinal image of an object gets smaller as they get further away

Question 16

what can change, even if an object looks the same size at different distances?

Answer 16

the retinal image size

Question 17

what happens to the retinal image when the object is at an increased distance?

Answer 17

retinal image size decreases

Question 18

what happens to the retinal image when the object is at a decreased distance?

Answer 18

the retinal image size decreases

Question 19

size constancy

Answer 19

the ability for an image to look the same size despite changing retinal image size

Question 20

Emmert’s law

Answer 20

1) objects that generate retinal images of the same size will look different in physical size if they appear to be located at different distances
2) the perceived size of an object increases as its perceived distance from the observer increases
3) an object of constant size will project progressively smaller retinal imaged as its distance from the observer increases
4) if retinal images of two different objects at different distances are the same, the physical size of yeh object that is further away must be larger than the one that is closer

Question 21

relative height

Answer 21

as an object gets further away, the nearer they get to the horizon
if the objects are below eye height, the highest object is furthest away
if the objects are above eye height, the lowest object is the furthest away

Question 22

atmospheric perspective

Answer 22

distant objects appear less sharp because there is more air and particles to look through

distant objects appear more blue as blue light is scattered by the atmosphere

Question 23

familiar size

Answer 23

for a larger object in real life to be perceived as the same size as a smaller object in real life, it must always be further away

Question 24

linear perspective

Answer 24

lines that are parallel in a scene converge as they get further away
(remember the retina is curved)

Question 25

shading and shadow

Answer 25

attached shadows
the shading that results from the depth within an object is a cue to depth
detached shadows

Question 26

why is the meaning of shadows ambiguous?

Answer 26

a depression and an elevation in a surface will be shaded on one side, telling the difference relies on knowing the direction of the light source

Question 27

where do we assume all light sources come from?

Answer 27

above

Question 28

attached shadows

Answer 28

shadows within an object

Question 29

texture gradient

Answer 29

texture becomes smaller/ finer as distance increases

Question 30

motion produced cues

Answer 30

cues that depend on movement of the observer, or movement of objects in the environment

Question 31

types of motion-produced cues

Answer 31

motion parallax

deletion and accretion

Question 32

motion parallax

Answer 32

an observer moves relative to 3D space, nearby objects appear to move rapidly while far away objects appear to move slowly

Question 33

motion parallax informs you of

Answer 33

1) relative direction

2) amount of motion

Question 34

who uses motion parallax?

Answer 34

animals that dont have much binocular overlap

head bob and orthogonal running

Question 35

deletion

Answer 35

as one object moves in front of another, deletion occurs

-front object covers more of the back object

Question 36

accretion

Answer 36

as one object moves away from another, accretion occurs

front object covers less of the back object

Question 37

binocular disparity

Answer 37

a cue that depends on the fact that slightly different images of a scene are formed on each eye

Question 38

what causes our binocular disparity? what is it dependent on?

Answer 38

because our eyes are in slightly different positions, determined by the distance between them

Question 39

how does binocular disparity cue for depth diminish?

Answer 39

with distance

Question 40

another name for binocular disparity

Answer 40

binocular stereopsis

Question 41

what is the basic of stereoscope 3D movies?

Answer 41

binocular disparity

Question 42

corresponding retinal points

Answer 42

for every point on one retina there is a corresponding point if the other

• these two points would be identical if one retina was moved to superimpose the other retina
• when you fixate on an object it will stimulate corresponding points on the eyes

Question 43

non corresponding retinal points

Answer 43

regions on the retinae that would not overlap if you slid one retinae on top of the other

separated on the retinae and cause disparity

Question 44

what does the amount of disparity tell us

Answer 44

how far an object is from our focus

Question 45

what is stereo blindness?

Answer 45

people that appear to lack mechanisms for processing disparities

Question 46

how many people show stereo blind performance?

Answer 46

2-5% of people

Question 47

what is the usual cause of stereo-blindness?

Answer 47

strabismus in early childhood prevents the normal development of binocular disparity detecting cells in the visual cortex

Question 48

what is strabismus?

Answer 48

misalignment of the eyes, failure to converge on a common target

Question 49

hyperstereo

Answer 49

can give increased depth form disparity

Question 50

stereogram to create 3D image

Answer 50

present same stimulus in both eyes but shift one slightly to the left or right
the shifted one will appear to be displaces in depth ad create a 3D image