Motion Perception

functions of motion perception

break camouflage, attract attention, segregate objects from the background, interpret events, determine the structure of objects, determine what actions people are performing

kinetic depth effect

the perception of a 3D structure from the motion of a 2D structure

akinetsopia

an inability to perceive motion due to either disease or trauma affecting the part of the brain responsible for motion perception

how do people with akinetsopia perceive the world

things appear still, but when they look away and look back, they had moved, like patient L.M.

when do we perceive motion

real motion, illusory motion, motion after effects, induced motion

illusory motion

when we perceive motion when nothing is actually moving

apparent motion

occurs when a series of stationary images are presented in succession to give the impression of motion

when does apparent motion not work

when the stationary images are presented too far apart

what is apparent motion insensitive to

colour changes, however these can be used to disambiguate ambiguous apparent motion

motion aftereffect

after viewing a moving stimulus for a short time, if you shift your gaze to a stationary object it will appear to move

induced motion

a nearby object effects the perceived motion of a second object, or causes a second object to appear to move, eg. moving background causes a stationary object to appear to move

motion induced blindness

motion makes things disappear

motion induced change blindness

when objects move, it is more difficult to notice changes (eg. colour changes)

why doesn't change blindness happen in everyday life

motion transits cue you to the part of the image that changes

why does motion induced change blindness occur

when things are moving, there are transient signals associated with all objects, not just the ones changing, so it is harder to notice changed

what does the footsteps illusion show

lower contrast objects appear to be moving slower than higher contrast objects

aperture problem

if you can't see the ends of a line, the movement of a line is ambiguous and is captured by the movement of the terminators (points where the line joins the aperture)

what does the aperture problem show

when the terminators move horizontally, the line appears to move horizontally; when the terminators move vertically, the line appears to move vertically

barber pole illusion

the lines always appear to move up or down because there are lines curving around the cylinder that create visual terminators that move vertically

who introduced the idea of motion aftereffect?

Mather et al. in 2008

Who created the footsteps illusion and in which year?

Anstis in 2003