motion perception Flashcards
function of motion perception
help break camouflage, help attract attention, help segregate objects from the background, help us interepret events, determine structure of objects and determine what actions people are peforming
Break camouflage
a camouflaged animal can be virtually invisible, until it moves, so motion attracts attention and helps us segregate objects from the background.
Interpret events
By seeing how objects interact, you can infer causality relationships, and even social relationships. (triangle and circle video)
Structure from motion
Motion can also allow us to infer structure by determining the shape of a moving object. (kinetic depth effect video)
interpreting actions
Motion can allow us to interpret actions, while static poses= ambiguous, when someone moves their actions and intentions often become clear (point light ‘walkers)
Life without motion perception
akinetopsia= person unable to percieve motion, L.M had akinetopsia and therefore has difficulties pouring tea, crossing the street and following speech because they could see that things had moved but couldnt see them moving
When do we perceive motion/
Real motion, Illusory Motion, Motion aftereffects, induced motion.
Illusory motion
static image- rotating snakes illuision appears to be moving- the percieved motion is caused by contrast between the colours.
Apparent motion
Apparent motion- occurs when a series of stationary images are presented in succession to give the impression of motion. For apparent motion to occur, as seperation between objects increases, alternation rate needs to decrease (third law of apparent motion)
Motion aftereffect
After staring at a moving waterfall fo several minutes, he then shifts his gaze to rockface, which appears to move upwards.
Induced motion
a nearby object (large) either affects the perceived motion of a second object (usually a small one) or causes a second object to appear to move.
Motion induced blindness
Motion can also make images dissapear. It can make it hatd to notice changes ( when the dots are stationary, it is very easy to notice them changing colour) Normally transient signals associated with color change, but when things are moving the transient signals associated with all objects- not just the ones changing colour.
Motion illusions
Motion illusions can inform up of the processes of underlying motion perception, for example the footsteps illusion. By fixating on the red cross the yellow and blue objects appear to speed up and slow down asynchronously. (when the contrast is high they appear to move faster, when it is low, they appear to move slower.
