motion perception

Question 1

ways eyes move

Answer 1

vergence movements
- movement of eyes to keep focus on image
- convergence and divergence

saccadic movements
- most common
- very fast, involuntary movements of both eyes
- move fovea towards object of inerest
- typical fixation lasts about 250ms

pursuit movements
- movements in order to keep fovea focused on moving target

vestibular ocular reflex
- involuntary reflex
- stabilises visual field and image of retina even when head moving

Question 2

eye movements when in fixation

Answer 2

microsaccades
- small rapid eye movements
- approximately 25ms in duration

drift
- randomly occurring, slow, irregular
- smooth motion eye movements

temor
- smallest type of eye movements
- result on antagonistic muscles counteracting to hold fixation

world doesn’t fade when we fixate
eyes always moving

Question 3

Riggs et al

Answer 3

stabilised retinal images

wear contact lenses with small mirror
image projected to mirror reflected onto screen
image participant sees will move in line with eye movements so image itself is always projected onto the same area of retina

to begin image appears normal
fades after a few seconds
after short time, image cannot be seen

unvarying stimuli will disappear from awareness as receptors adapt to stimuli

Question 4

function of motor perception

Answer 4

detecting things in our environment = survival advantage
perceiving objects accurately
perceiving events
social perception

Question 5

Akinetopsia

Answer 5

motion blindness
can result from disease or damage due to trauma or stroke
related to dysfunction with area MT/V5 responsible for motion detection

Question 6

what elicits motion perception

Answer 6

real physical movement
- when something in environment really moves across field of view

apparent motion
- when alternating or successively present stimuli appear to be one moving stimulus

induced motion
- occurs when motion of one object causes a nearby stationary stimulus to appear to move in opposite direction
- results from neural adaptation and rebound responses

Question 7

real vs apparent motion - Larsen et al

Answer 7

presented 3 displays to participants
control - 2 squares flashing simultaneously
real motion - one square moving back and forth
apparent - 2 squares flashing alternately

different parts of the brain were activated

Question 8

perceptual organisation of moving objects

Answer 8

structure from motion
- stationary objects are much more difficult to detect than moving objects
- utilised by prey animals to avoid detection

motion induced blindess
- suppressing stationary objects may help perceptual organsisation

motion capture
- small elements that enclosed within a larger figure appear to move with the figure
- enclosed fingers appear to move coherently, until line broken

kinetic depth
- based on the motion parallax monocular depth cue
- points of an object that are moving faster than others are perceived as closer, creating illusion of 3D rotation

Question 9

biological motion Johansson

Answer 9

only few markers are needed to elicit the perception of biological motion

Question 10

Grossman and Blake

Answer 10

specialised brain area for biological motion

specialed network in brain responsible for perception of biological motion
primarily involves small area of the superior temporal sulcus