Week 6 - Space and motion perception

Question 1

what are the dorsal and ventral pathway otherwise known as

Answer 1

dorsal = where
ventral = what

Question 2

space perception

Answer 2

• we perceive 3D space and objects (depth and distance)
• retinal image is 2D

Question 3

monocular pictorial cues - depth cues

Answer 3

• occlusion
• linear perspective
• size
• texture gradient
• atmospheric perspective
• shading
• height in the visual field

Question 4

Occlusion

Answer 4

one object overlapping another in our visual field, the overlapping object is perceived as being close

Question 5

linear perspective

Answer 5

when two parallel lines appear to converge the further away they are

Question 6

size

Answer 6

When objects are the same size but appear smaller we can interpret the smaller objects as being further away

Question 7

texture gradient

Answer 7

the density and detail of a surface’s texture change with distance. The further away a surface is the texture elements appear smaller, closer together and less detailed

Question 8

atmospheric perspective

Answer 8

As distance increases atmospheric particles scatter light, causing distant objects to appear hazier, lighter in colour, and less detailed

Question 9

shading

Answer 9

variations in light and shadow across a surface help our brain interpret the shape and orientation of objects

Question 10

height in the visual field

Answer 10

objects that appear higher up in the field of view are generally perceived as being farther away

Question 11

Monocular movement cues - Kinetic depth effect

Answer 11

A 2D pattern can be perceived as providing depth information when moving e.g. dancer spinning

Question 12

Monocular movement cues - Motion Parallax

Answer 12

• objects closer to you move more as compared with objects farther away
• the direction of movement changes according to whether objects are closer to or farther away from you relative to your fixation point

Question 13

Stereopsis

Answer 13

the process in which the brain combines slightly different images from each eye to create a single, 3D perception of the world.

Question 13

Binocular cues - Binocular disparity

Answer 13

• retinal images are slightly different between the two eyes
• the greater the disparity, the farther the object
• the direction of the disparity indicates whether objects are closer or farther relative to the fixation

Question 14

Non-retinal cues - accommodation

Answer 14

muscles that change the thickness of the lens provide some information about distance to a focused object

Question 15

Non-retinal cues - convergence

Answer 15

inward/outward rotations of the eyeballs correspond to the distance to a focused object

Question 16

When cues are ambiguous/insufficient

Answer 16

• Necker cube
• Schroeder stairs
• These 2D patterns cause bistable perception

Question 17

Motion perception

Answer 17

• objects in the environment are constantly moving
• when they are not in motion, you are rarely perfectly still
• Our visual perception is based on dynamic retinal images

Question 18

Observer movement

Answer 18

Optic flow: as we move through the 3D environment, different parts of a retinal image move in different directions, depending on how we move and where our eyes are focused

Question 19

Object movement

Answer 19

Looming:
- a pattern on a retinal image gradually increases its size as it approaches an observer

Question 20

How can you tell is an object is moving towards you or you’re moving towards an object?

Answer 20

• non-visual self motion information
• optic flow

Question 21

biological motion

Answer 21

• structured patterns of motion that are unique to animate objects
• point-light displays that only indicate joint movements are sufficient for us to perceive human action
• some of this ability may be innate - 2-day old infants show sensitivity to biological motion

Question 22

Illusory (apparent) movement

Answer 22

where static images or patterns create the perception of movement even if nothing is moving.

Question 23

stroboscopic effects

Answer 23

when a series of still images or short flashes of light are shown in rapid succession, creating the illusion of smooth continuous movement