motion

Question 1

why do we perceive motion

Answer 1

• object recognition: motion can act as a distinguishing feature from the background
• biological motion: can give us information on gender, size ect.
• attentional capture:: signal for things worth paying attention to

Question 2

real motion

Answer 2

something moving around in the environment

Question 3

appparent motion

Answer 3

2 dots in different locations blinking alternating tends to perceive as 1 dot moving

Question 4

induced motion

Answer 4

background moving induces movement

- motion of one thing effects perception of movement of another

Question 5

motion aftereffect

Answer 5

keeping eyes fixed on motion - cells adapt over time and even after motion stops you perceive motion

Question 6

reichardt detector

Answer 6

uses temporal delay to create spatial summation
- stimulus passes over A, delay unit slows down signal A
- sitmulus passes over B, signal B and A reach output unit at the same time and fires AP
tuned for direction and speed

Question 7

disturbance in optic array

Answer 7

• stationary eyes, moving object (detected)

- moving eyes, stationary object (Reichardt alone cannot detect)

Question 8

global optic flow

Answer 8

moving eyes, stationary objects

- reichardt detectors alone cannot account for this

Question 9

corollary discharge theory

Answer 9

signal about whether or not eyes are moving (motor signal)

CDS: copy of motor signal sent to brain

Question 10

when does Corollary discharge theory detect motion

Answer 10

stationary eye, moving stimulus (IDS)

moving eye, moving stimulus (CDS)

Question 11

when doesnt Corollary discharge theory perceive motion

Answer 11

eye moves across stationary scene (IDS and CDS)

- notices eyes moving and scene moving so realizes there isnt any real motion

Question 12

real motion neuron

Answer 12

detects motion when bar sweeps across RF

doesnt detect motion when eye sweeps across bar

Question 13

directional tuning of MT neuron

Answer 13

• each neuron tends to best detect motion in a certain direction

Question 14

what is the aperture problem

Answer 14

• a single motor neuron sees only a small portion of movement that may not be representative of the bigger picture
• real movement may potentially be in a different direction
  “ the local percept follows line orientation and the global percept follows the direction of movement”

Question 15

aperture problem solutions

Answer 15

1. following the end of the bar (end stopped V1)
   - direction selective but not orientation
2. dynamic direction tuning
   - integrate information over time, first see orientation then see direction

Question 16

3 ways of perceiving motion-

Answer 16

time delayed coincidence detectors- reichardt
subtract changes due to eye movement- CDS
integrate signals across space- solve aperature

Question 17

where in the visual cortex does motion perception occur

Answer 17

V1- local visual field (reichardt detectors)
MT- global real motion, not tricked by eye movements and integrates motor/temporal information
- part of dorsal pathway

Question 18

complex cells

Answer 18

respond to orientated bars that move in a specific direction

located in V1

Question 19

comparison of behavioral and neurometric functions

Answer 19

response of a single neuron in MT almost perfectly explains behavioral response to motion stimuli

Question 20

transcranial magnetic stimulation

Answer 20

runs high volt electricitiy and disrupts MT

• person can no longer judge direction of motion
• person may experience flashes in visual field

Question 21

MST and optic flow

Answer 21

medial superior temporal area

• keeps track of motion information (optic flow)
• how we move in regards to environment
• things in the center will move out to the sides of visual field

Question 22

superior temporal sulcus and biological motion

Answer 22

responsible for the perception of biological motion

- gender, size, state of mind, emotion information

Question 23

summary of brain areas for motion perception

Answer 23

V1- local motion
- direction of motion across receptive field
MT- direction and speed of object motion
- global motion
MST- processing optic flow, locating moving objects
- understand how to navigate through environment
STS- perception of biological motion