Sensation & Perception 3 Flashcards
What are the figural cues?
regions of the image are more likely to be seen if:
- they are in the front of the image
- at the bottom of the image
- convex
- recognisable
What is the gist of a scene?
- getting an overall impression of what the scene is about
How long do you need for gist perception?
about 40 ms???
Function of motion perception
- help break camouflage
- help attract attention
- help segregate objects from background
- help us interpret events
- help us determine structure of objects
- help us determine what actions people are performing
What happens when camouflaged animal moves?
attention is attracted to it & its camouflage is broken – MOTION ATTRACTS ATTENTION & HELPS US SEGREGATE OBJECTS FROM BACKGROUND
How does motion allow us to interpret events?
by seeing how objects interact, you can infer causality relationships & even social relationships
What is kinetic depth effect?
determining shape of moving object
What is kinetic depth effect?
determining shape of moving object
How does motion allow us to interpret actions?
- static poses are often ambiguous
- when someone moves, their actions & intentions are often made clear
- usually demonstrated using point-light walkers
What are point-light walkers?
- created by placing lights on a person’s joints and having them perform an action
- videoed so only the lights can be see
What is akinetopsia?
inability to perceive motion due to brain damage
E.g. of akinetopsia patient
- L.M. had difficulties pouring a cup of tea, crossing the street, following speech
- could see things had moved but couldn’t see them moving
When do we perceive motion?
- REAL MOTION (actual movement)
- ILLUSORY MOTION (nothing actually moving e.g. rotating snake illusion)
- MOTION AFTEREFFECTS
- INDUCED MOTION – moving background (or moving object) causes a stationary object to appear to move
When does apparent motion occur?
when a series of stationary images are presented in succession to give the impression of motion e.g. 2 separate dots on slide
only works if dots are close together + alternation rate is at a good speed
as separation increases alternation rate needs to decrease –> KORTE’S THIRD LAW OF APPARENT MOTION
What is apparent motion mostly insensitive to?
colour changes
What can colour be used to do?
to disambiguate ambiguous apparent motion
What is induced motion?
- a nearby object or background (usually a large one) either affects the perceived motion of a second object (usually a small one) or causes a second object to appear to move
What is motion aftereffect?
When you’ve been driving down a long, straight road, and you suddenly come to a stop, does the road seem to rush away from you? When you look at a waterfall, then glance away, does it seem as though the scenery is flowing upwards? It’s called motion aftereffect, and it’s a kind of visual adaptation.
EXPOSURE TO MOTION IN OPPOSITE DIRECTION
Motion induced change blindness
- can make it harder to notice changes
- normally colour changes attract attention bc of the transient signals associated with the change (e.g. flicker)
- however when things are moving there are transient signals associated with all objects not just the ones that are changing
- thus attention is no longer drawn preferentially to the changing objects so the changes are not noticed
Motion illusions can inform us of. . .
the processes underlying motion perception
e.g. the footsteps illusion shows us that contrast affects motion perception
