Topic 3: Motion

Question 1

receptive field size

Answer 1

varies with brain region
v1 < v2 < v4
eccentricity (fovea < parafovea < periphery)

Question 2

visual field degrees of eccentricity

Answer 2

100 degrees within VF

large portion of visual field gets info from both eyes

Question 3

why do we perceive motion

Answer 3

object recognition
info from biological motion
attentional capture

Question 4

real motion
apparent motion
induced motion

Answer 4

• when something is actually moving
• nothing is actually moving and is uncommon in natural world, 2 dots blinking but brain creates connection
• background moves so we perceive motion relative to the background

Question 5

motion aftereffect / waterfall effect

Answer 5

detectors in visual system become fatigued for that particular direciton
when not seeing motion these detectors arent working at baseline and brain thinks its motion

Question 6

illusory motion

Answer 6

you think something is moving when it actually isnt

circles that look like theyre moving

Question 7

reichardt detector

Answer 7

uses temporal delay to create spatial summation
-two sensory cells next to each other and they both send output to same cell
-cell A has a delay and cell B sends it directly, needs to receive both signals at the same time
tuned for direction and speed

Question 8

reichardt detector problem

Answer 8

alone cannot explain motion

-detectors would think it is motion even if you are moving your eyes if the room is still

Question 9

collary discharge theory

Answer 9

when something moves in VF its called image displacement signal
brain sending signal to eye muscles, copy of moto command well be sent to perception signal
copy = collary discharge signal
-if eye moves it means something else is moving

Question 10

aperture problem

Answer 10

any given neuron doesnt see whole world only small portion it falls within
local percept follows line orientation, global follows direction of movement
problem is solved when you can see end of the bar

Question 11

end stopped v1 cell

aperture problem solution

Answer 11

selective for end of a bar, irrespective of orientation
colour in graph determines how mich neuron is firing
placement within VF is determined by where end of bar is

Question 12

area MT (visual system)

Answer 12

have neurons that respond to global real motion
-details build up as we move through visual system
real motion and integration, basis for perception of motion

Question 13

complex cells

Answer 13

respond to oriented bars that move in specific direction

Question 14

Britten et al

MT single cell recording

Answer 14

comparing behavioural responses in area mt
dots moving in same direction and increasing ambiguity with different trials
-psychometric and neurometric functions match almost perfectly

Question 15

Area MT TMS

Answer 15

induce motion phosphenes (think light enters eye when it actually doesnt)
interfere with motion perception

Question 16

other motion areas

Answer 16

medial superior temporal area (MST)

superior temporal sulcus (STS)

Question 17

optic flow

Answer 17

moving and expanding out along a certain line
driving and things coming into VF
start in the middle of VF when far and then moves to the side
mediaul superior temporal sulcus

Question 18

STS

Answer 18

ability to recognize motion info and interpret it as biological info
-group of dots can be seen as person walking

Question 19

striate cortex (V1)
middle temporal areas (MT)
MST
STS

Answer 19

• direction of motion across small receptive field
• direction and speed of object motion
• processing optic flow, locating moving object, reaching for moving objects
• biological motion

Question 20

scanimation

Answer 20

series of photos with black and white stripes that make the appearance of motion
apparent motion - brain is filling in spaces to think its motion

Question 21

lenticular/photicular images

Answer 21

uses sliced images as in scanimation
-instead of picket fence bars, a sheet of narrow ridge like plastic lenses controls which set of slices are available
by moving eye, lenses or image, a different set of slices become available