depth and size pt1

Question 1

why do we perceive size/depth

Answer 1

size and object recognition

Question 2

what is the challenge of depth and size perception

Answer 2

distal stimulus is a 3D object in the world
proximal stimulus is 2D on the retina
we must recover 3D from 2D somehow
- objects at different distances cast identical images on the eye (small and close up is the same as far and large)

Question 3

oculomotor

Answer 3

cues based on movement of eye muscles

Question 4

what are oculomotor cues

Answer 4

convergance: inward movement of eyes when focusing on nearby objects
accomodation: shape of lens changes when we focus on objects at different distances
- brain infers how far away an object is by how much muscles move

Question 5

monocular-

Answer 5

cues available from a single eye

Question 6

monocular cues for depth

Answer 6

1. pictoral - depth information available in an image
   ex. occlusion, relative height, familiar/relative size, perspective convergance, atmospheric perspective, texture gradient, shadows
2. motion cues- sources of depth info due to motion
   ex. motion parallax, deletion/accretion

Question 7

relative vs actual depth

Answer 7

relative- depth of objects compared to eachother

actual- distance from observer

Question 8

occlusion

Answer 8

one object partially covers another

- good for relative depth

Question 9

relative height

Answer 9

objects closer to the horizon line appear more distant

- relative depth

Question 10

familar/ relative size

Answer 10

familiar: distance info is based on knowledge of objects size (soccer ball is same size as close up baseball)
relative: for objects of equal size, closer one takes up more of visual field (closer one appears bigger)
- actual depth

Question 11

perspective convergance

Answer 11

parallel lines appear to come together in distance

- actual

Question 12

atmospheric perspective

Answer 12

distance objects are fuzzier and have a blue tint

- relative

Question 13

texture gradient

Answer 13

equally spaced elements are more closely packed as distance increases
- relative

Question 14

shadows

Answer 14

shadows indicate where objects are located

Question 15

motion parallax

Answer 15

things closer to the train move by very fast where as things furthur from the train move slower
- actual

Question 16

deletion/accretion

Answer 16

objects are covered (deletion) or uncovered (accretion) as we move relative to them or they move relative to us

ex. pig getting deleted may be behind the barn
- relative