| What are the functions of motion perception? | Help break camouflage.
Help attract attention.
Help segregate objects from the background.
Help us interpret events.
Help us determine the structure of objects.
Help us determine what actions people are performing. |
| How can motion help us interpret events? | Helps us to infer causality relationships and social relationships. |
| How can motion help us to infer structure? | Help determine the shape of a moving object - "kinetic depth effect".
Help infer 3D shape. |
| How can motion help us interpret actions? | Static poses are often ambiguous.
Therefore when someone moves, their actions and intentions are often made clear. |
| What is akinetopsia? | Not being able to perceive motion - "motion blindness".
Can see when objects have moved but cannot perceive them moving. |
| When do we perceive motion? | Real motion (something actually moving).
Illusory motion (nothing actually moving, includes static images/illusions and apparent motion).
Motion aftereffects.
Induced motion (e.g. moving background or object causes as stationary object to appear to move). |
| What is apparent motion dependent on? | Objects have to be close enough and alternation rate slow enough, otherwise they will be perceived as two separate flashing images.
For apparent motion to occur, as separation increases, alternation rate needs to decrease - Korte's Third Law of Apparent Motion (Korte, 1915). |
| What role does colour have in apparent motion? | Apparent motion can still occur when objects are of different colours.
However colour can also help disambiguate ambiguous apparent motion. |
| What is motion aftereffect? | When you focus on a moving object and then shift your gaze towards a stationary object, which then is perceived to move.
e.g. the waterfall effect. |
| What is motion induced blindness? | It is harder to notice change when things are moving. |
| How does contrast affect motion perception? | Higher contrast objects appear to move faster.
Lower contrast objects appear to move more slowly.
e.g. footsteps illusion, cars moving through fog appear slower. |
| What is the aperture problem? | Occurs when the ends of a line are obscured by an object.
When terminators(points where line joins aperture) move horizontally, line appears to move horizontally.
When terminators move vertically, line appears to move vertically.
e.g. barber pole illusion. |
