Motion perception Flashcards
What is position-motion dissociation?
Motion can be experienced vividly in conditions where its change in location cannot be discriminated or when it is physically stationary
What are the two examples of position-motion processing?
Motion adaptation aftereffect
Fine grain motion illusion
Motion adaptation aftereffect
Adatping to a target in mortion in one direction causes a subsequently viewed target that is physically stationary to appear to move in the opposite direction
Fine grain motion illusion
When two similar targets are flashed consecutively in the retinal peripherym subject experiences motion when the separation between individual targets is below the resolution limit
What type of motion can the reichard motion detector detect?
First order
First order mechanisms
Motion defned y spatial displacement of luminance
Can be processed by simple cortical cells
Second order mechanisms
Motion defined by contrast envelopes
Can be processed by compelx cortical cells
Third order mechanisms
Motion created by displacement of salient features over time
Velocity
Rate of change of position of a target in a given direction
How do you measure velocity?
temporal frequency/spatial frequency
What are the different types of motion?
Real
Apparent
Induced
Inferred
What is real motion?
Target physically moves across the retina
What is apparent motion?
Motion produced by the sequential flashing of similar targets with spatial displacments
What is beta-motion?
Apparent motion that flashes between 60-200msec and is seen as a single target that translates spsce
What is PHI motion?
Apparent motion that flashes at 60msec and is perceived as a shapless form that moves
What are the two theories on why the form takes the color of the background in PHI motion?
Occlusion (form blocks the shape)
Physiological (rate of flicker isolates the motion system)
What is induced motion?
Smaller stationary targets are perceived to move when presented in the vicinity of larger moving targets
What is inferred motion?
Motion that is inferred by the displacement of a target over an extended period of time
What are 4 regions of the brain that process motion?
Superior temporal sulcus
MT/V5
V3A
V1
What is akinetopsia?
Syndrome in which patient loses the ability to perceive visual motion following cortical lesions outside the striate cortex
