17. Sensation & Perception: Depth & size perception

Question 1

what are the ways we perceive depth (3)?

Answer 1

1. oculomotor cues
2. monocular cues
3. binocular cues

Question 2

what are oculomotor cues?

Answer 2

cues based on our ability to sense the position & state of our eyes

Question 3

what are monocular cues?

Answer 3

cues based on the visual information available w/in 1 eye

Question 4

what are binocular cues?

Answer 4

cues that depend on visual information w/in both eyes

Question 5

what are the 2 main oculomotor cues?

Answer 5

1. binocular convergence
2. accommodation

Question 6

what are the 3 main monocular cues?

Answer 6

1. accomodation
2. pictorial cues
3. movement based cues

Question 7

what are the 7 main pictorial cues?

Answer 7

1. occlusion
2. relative height
3. familiar & relative size
4. perspective convergence
5. atmospheric perspective
6. texture gradient
7. shadows

Question 8

desc atmospheric perspective

Answer 8

• GENERALLT, things further away are obscured by the atmosphere (e.g mountains, fog)
• can use it to estimate the distance of objects

Question 9

desc texture gradient

Answer 9

• by estimating how rough or smooth smth is, you can gauge its distance
• smooth = close
• rough = far

Question 10

desc how shadows are a cue for depth perception

Answer 10

• humans assume light comes from above (cause of sun)
• perceive that the object which casts a shadow on another is closer to the light source (front) than the thing it shadows

Question 11

what are the movement based cues (2) ?

Answer 11

1. motion parallax
2. deletion & accretion

Question 12

desc motion parallax

Answer 12

• closer objects tend to move past you more quickly that objects further away
• becuz the retinal image tends to move faster for closer objects
• in the same amount of time, an object further away will move less distance (perceive it as moving slowly)

Question 13

desc accretion & deletion:

Answer 13

• close by objects sometimes occlude (block) a far away object
• far away objects may be visible at 1 point, but when you move, the closer object will mask it
• unable to see the further object (deleted from POV)

Question 14

binocular disparity is the slight ____ in which each ___ views an ___

Answer 14

DIFFERENCES
EYE
OBJECT

Question 15

Binocular disparity occurs due to …

Answer 15

the lateral separation of the eyes

Question 16

point of fixation ____ alter relative disparity

Answer 16

DOESN’T

Question 17

any point on the _____ has ___ absolute disparity

Answer 17

HOROPTER
ZERO

Question 18

absolute disparity is the …

Answer 18

difference b/w the right & left eye’s retinal position

Question 19

whichever object is fixated on has ___ _______ ______

Answer 19

ZERO ABSOLUTE DISPARITY

Question 20

zero absolute disparity means that …

Answer 20

the left & right images of the object fall onto CORRESPONDING parts of the retina

Question 21

what is the correspondence problem?

Answer 21

• if there are many identical objects in the scene it becomes hard to figure out which images in the left retinal image should be associated with which images in the right retinal image
• cuz retinal images can be ambiguous

Question 22

how do associations become unambiguous in the correspondence problem?

Answer 22

1. if the object in the visual scene are made distinct from each other
2. by colour (each a diff colour)

Question 23

what 2 factors determine the perceived size of an object?

Answer 23

1. its angular size
2. its perceived depth

Question 24

angular size is … (2)

Answer 24

• the visual angle an object subtends
• the closer an object to the person, the larger its angular size

Question 25

desc the phenomenon of size constancy (3)

Answer 25

- perceived size depends on its physical distance - when an object is far away, it appears to be SMALLER than when its close, but we KNOW that the size hasn't changed - to achieve this, need to consider: the size of the retinal image & the dist of the object

Question 26

what is the formula for size constancy?

Answer 26

S = K x ( R x D ) S = apparent size of an object K = a constant R = size of the retinal image D = perceived dist to the object

Question 27

why are size & apparent depth so closely linked?

Answer 27

due to SIZE CONSTANCY - if someone misestimates the dist of an object, they will prob misestimate the size of an object

Question 28

most size illusions are caused by ____ the dist to an object so that it appears ...

Answer 28

MISTAKING LARGER/SMALLER

Question 29

if an object appears closer than it really it, it is ___ than it really is

Answer 29

SMALLER

Question 30

if an object appears further away than it really it, it is ___ than appears

Answer 30

LARGER

Question 31

what did Holway & Boring investigate?

Answer 31

how depth cues influence size judgement

Question 32

desc the Holway & Boring Exp (3)

Answer 32

1. observer sat @ intersection of 2 corridors & could view a test circle in 1 & comparison circle in other corridor 2. task: adjust the size of the comparison to match the test 3. test circles were of diff sizes but presented @ diff distances so that their ANGULAR SIZE WAS ALWAYS THE SAME

Question 33

____ size estimates can only occur when ___ to the object can be ____ _____

Answer 33

ACCURATE DISTANCE ESTIMATED ACCURATELY

Question 34

when there are sufficient ___ ___, the ___ of the test patch can be accurately estimated

Answer 34

DEPTH CUES SIZE

Question 35

what were the 3 depth cues investigated in Holway & Boring?

Answer 35

1. Binocular disparity 2. Motion parallax 3. Shadows

Question 36

How is size constancy achieved?

Answer 36

by considering both the size of the retinal image & the distance of an object

Question 37

what cues indicate relative depth? (4)

Answer 37

- occlusion - atmospheric perspective - relative height - deletion & accretion

Question 38

what is the diff b/w absolute & relative disparity?

Answer 38

ABSOLUTE: changes as you fixate on diff objects - diff in the angular location of an object's image in the 2 eyes, indicating depth relative to the fixation point RELATIVE: constant for a pair of objects regardless of WHERE you're fixating - compares the depth of 2 objects/features, regardless of the fixation point