VSP Motion Perception
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What is the illusion of motion of one's entire self, as a result of motion in one's peripheral visual field?
- ex: sitting in stationary care and feel like you are moving
What does info about an object motion involve?
muscular, oculomotor control, vestibular systems
What does the retina use to percieve motion?
Visual pathway only
What two ways can retinal motion occur?
- 1. stationary eye and moving target
- 2. stationary target and moving eye
What is the perceptual disappearance of a stabilized retinal image called?
Will high or low spatial frequncies fade easier?
The human visual system is sensitive to ? in light simulation
The minimum amplitude of perceivable motion varies with what?
How small of a movement does stimulus need to make for a person to detect it?
- Foveal: approx 20 arc seconds or less
- (20deg = ~3 arc minutes)
How slowly can the stimulus move for a person to barely detect that it is moving? what is this called?
- Without reference 10-20 arc min/sec
- With reference much better: 1-2 arc min/sec
*10x better if you have nearby stationary reference stimulus to compare to the stimulus that is moving
Does percievable velocity incr or decr with increasing luminance?
5 ways by which an object might appear to move
- 1. real motion
- 2. illusionary motion
- a. autokinetic effect
- b. induced motion (motion contrast)
- c. motion aftereffects
- d. stroboscopic motion
What is it called when a small, stationary object viewed against an otherwise completely featureless VF will appear to move about randomly w/in a small area even though it's not really moving?
Autokinetic effect (type of illusory motion)
ex: small pt of light in dark room appears to randomly move
What is it called when a stationary object appears to move due to the motion of surrounding objects or contours?
Induced motion (an illusory motion)
- ex. motion of clouds makes moon like its moving
- or Reverse Spoke illusion
Induced motion is always percieved to be in what direction compared to that of the inducing objects and contours?
Special case of induced motion that only operates accross very short distances.
Illusory changes in the perception of motion that occur during prolonged viewing of moving objects or contours.
Illusory perception of motion of stationary objects or changes in the perception of motion of moving objects after prolonged viewing of moving objects of contours.
Prolonged viewing of an object moving at constant velocity may cause a decrease in the percieved speed of motion
ex. when driving going 70 mph and slow to 35mph now you feel like you are going extreeeemely slow
Motion detection and contrast detection thresholds increase during prolonged vieweing of moving objects or contours but only for objects or contours moving in the same or similar direction
Motion after effect (MAE) demonstrates...
binocular transfer (but weaker after effect in unadapted eye)
If the field viewed after adaptation contains contours moving in a direction w/in 30 degr of that of the adaptingmotion, the percieved direction of their motion may be altered by the adaptation.
2D directional afterefect
- ex: if you adapt to motion in 180 degr meridian, you may not be able to detect that objects are moving w/in 30degr of that motion
- *objects must move faster for you to detect they are moving
Examples of the motion after effect
- 1. waterfall illusion
- 2. spiral illusion
- 3. buddha example
Illusory motion resulting from the successive presentation of a stimulus at different locations along a continuous path. Also called>
Stroboscopic motion or "apparent motion"
example of stroboscopic motion
phi motion: lights on billboard turned on and off successively with optimal durations and intervals, appear to be a single light moving around perimeter of sign
4 types of stroboscopic motion
- 1. alpha motion
- 2. beta (phi)motion
- 3. gamma motion
- 4. delta motion
illusory motion of 2 stimuli in reverse direction when the luminance of one is signif higher than other
ex. in notes
illusory expansion and contraction of an object as its luminance is incr or decr on successive presentations
ex: as luminance incr in the square, it appears to expand
illusory motion of an object due to successive presenations at optimally spaced positions along a continuous path
ex: lights on billboard/marquee
illusory expansion or contraction of and object d/t successive presentations of difference sizes of the object
If you show incr sizes of same object in succession it looks like the object is moving closer to you
Laws that describe the relationships among various stimulus parameters necessry to maintain optimum phi motion when andy one parameter is changed.
Korte's laws; if you incr luminance you have to:
- increase spatial separation (space bw lights)
- decr interstimulus interval (time bw flashes)
Korte's laws; if you increase ISI (interstimulus interval) you have to:
- increase duration (amount of time the light is turned on)
- increase spatial separation (space bw the lights)
Which order of motion stimuli is the movement of areas or contours that is defined by their luminance.
Changing luminance over time
First order motion
most "real" moving objects, phi motion
Which order of motion stimuli is defined by mvnt of areas whose contours or shapes are defined by texture; and NOT by luminance. Example?
randot stereo test; motion defined form, coherent motion
Which order of motion stimuli is defined by mvnt of areas defined as "figure" with neither luminance nor texture boundaries. Example?
ex: isoluminant displays
Motion of elements that all share the same velocity (direction and speed) of motion. and what order of motion perception is this?
Coherent motion (2nd order motion)
ex dalmation in texture disappears when moved in a uniform direction and speed.
The object that we see is moving, using both eyes.
Cyclopean motion; Coherent motion against a static random element background.
Random element kinematogram (cinematogram)
Cyclopean motion; Coherent motion against a dynamic random element background (background in which each background element undergoes spatial displacements of random direction and/or magnitude)
random element correlograms (dynamic random element kinematograms)
ex: background moves in diff direction of shape
LIke random element stereograms , random element motion displays req solution of a...
"correspondance problem"(match image seen with either eye)
Minimum proportion of elements in a dynamic random element disply that must undergo the same velocity of motion for this to be detected.
ex in notes
Describe a clinical application of coherent motion threshold.
- randomly present different proportions of dots undergoing coherent motion on consecutive presentations in an n-alternative choice paradigm
- Forced choice: on each presentation, the subject guesses the direction of coherent motion
Minimum spatial displacemtn of elements necessary for the perception of stroboscopic motion
the minimum displacement threshold (Dmin
Clinical Example of the minimum displacement threshold (Dmin
typically 6-10 arc seconds (tell when lines on top of each other are 2 lines and not one)
What is the maximum spatial displacement of elements that supports the perception of 2nd order motion? example
the maximumm displacement threshold (Dmax
max amount you could move the target/texture for them to still percieve it as a fluid motion, rather than it just jumping
Typical the maximum displacement threshold (Dmax) is
15 arc minutes
2 parts of Braddicks 2 process model of motion perception
- 1. short-range motion
- 2. long-range motion
Which part of Braddick's model supports 1st order motion (eg: continuous and phi motion)
Long range motion
Which part of Braddick's model supports 2nd order stroboscopic motion ?
Which motion perception of Braddicks model has spatial displacemnts within the Dmin to Dmax range?
short-range, 2nd order
Which motion perception of Braddicks model that operates with displacement larger than Dmax
Long range motion (1st order)
What does Braddicks model rely heavily upon?
In this Order of motion the perception of motion for stimuli whose contours are defined only by differences in color without any luminance or texture differences is very weak when compared with motion of stimuli definced by luminance or texture
3rd order (isoluminant) motion
Remaining 3rd order motion is thought most likely to depend on which pathway?
Sometimes a motion of a stimulus is...
This may influence perception of the direction of motion within
ex: barber pole illusion and figure ground segregation
Averaging of component motion vectors. The brain must average the direction of all stimuni it sees to decide which way things are moving.
Resolution of motion ambiguity
Correlations of motion velocity from different portions of a display. If sufficiently consistent witha a rigid transformation of size and shape in 3D space, may elicit the perception of depth from a 2D display.
Kinetic Depth Effect ("Depth" from Motion)
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