conclusions * t wo ( sub ) populations of motion sensors with with different characteristics must be...
TRANSCRIPT
CONCLUSIONS
* TWO (SUB)POPULATIONS OF MOTION SENSORS WITHWITH DIFFERENT CHARACTERISTICS MUST BERESPONSIBLE FOR THIS DIFFERENCE IN MAE-
DIRECTION.
* WHERE DO THESE MAES ORIGINATE?
*...EVEN MORE EXCITING RESULTS WILL BE PRESENTEDAT THE ECVP IN OXFORD (VAN DER SMAGT ET AL.)
Helmholtz Instituut
School for A utonomous Systems Research
Universiteit Utrecht
The Aftereffect of transparent motion: The Aftereffect of transparent motion: integration or segregation is determinedintegration or segregation is determined
by the type of test patternby the type of test pattern
Maarten J. van der SmagtMaarten J. van der SmagtFrans A.J. VerstratenFrans A.J. VerstratenWim A. van de GrindWim A. van de Grind
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Adaptation Speed (deg/s)
MA
E D
ura
tion
(s) Static test
Dynamic test
Expt. 1 Expt. 1 Verstraten Verstraten et al.et al. (ARVO '98) (ARVO '98)
Expt. 2 Expt. 2 Verstraten Verstraten et al.et al. (ARVO '98) (ARVO '98)
Static test Dynamic test
Adaptation Stimulus
Static test Dynamic test
Adaptation Stimulus
Purpose of this studyPurpose of this study
The The low speed channellow speed channel is tapped by the static test is tapped by the static test pattern.pattern.
The The high speed channelhigh speed channel is tapped by the dynamic is tapped by the dynamic test pattern.test pattern.
What happens if we construct a test pattern What happens if we construct a test pattern that has that has bothboth static static andand dynamic dynamic characteristics….characteristics….
Do both channels Do both channels interactinteract in the MAE ? in the MAE ?
How does this interaction depend on parameters How does this interaction depend on parameters like:like: component direction and speed ?component direction and speed ? test contrast ?test contrast ? the relative strength of both static and dynamic the relative strength of both static and dynamic
components in the test pattern ?components in the test pattern ?
MethodMethodAdaptation:Adaptation: Transparent motion, consisting of two componentsTransparent motion, consisting of two components
(RPA, 256*256 pixels).(RPA, 256*256 pixels).
component 1: 1 deg/s (1 pixel/ 4 frames). component 1: 1 deg/s (1 pixel/ 4 frames). component 2: 32 deg/s (8 pixels/ 1 frame).component 2: 32 deg/s (8 pixels/ 1 frame).
Test:Test: Test pattern consisting of two components.Test pattern consisting of two components.
component 1: stationary RPA. component 1: stationary RPA. component 2: dynamic RPA component 2: dynamic RPA (refreshed every 2 frames, = (refreshed every 2 frames, =
45Hz).45Hz).
StimuliStimuli
Component 1 Component 2 Superimposed
spacetime
space
time
space
timeA
DAPT
space
time
spacetime
space
timeT
EST
Summary of main resultSummary of main result
orthogonal sameopposite slow only fast onlyADAPT
MAE
ParametersParameters Component Component directiondirection::
no influence on percept.no influence on percept.
Component Component speedspeed::as long as both components fall well within as long as both components fall well within onlyonly one of one of
the speed tuning curves.the speed tuning curves.
(mean) Test (mean) Test contrastcontrast::no influence on percept.no influence on percept.
RatioRatio of test components of test components (Static-Dynamic Ratio; (Static-Dynamic Ratio; SDRSDR):):A A transparenttransparent MAE is perceived, as long as both MAE is perceived, as long as both
components are clearly visible in the test stimulus.components are clearly visible in the test stimulus.
Results individual components (RAJ)Results individual components (RAJ)
0.01 0.1 1 10 100
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0.01 0.1 1 10 100
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0.01 0.1 1 10 100
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Static-Dynamic Ratio (SDR)
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(s) opposite, orthogonal, same
Static component Dynamic component
Results individual components (TL)Results individual components (TL)
Static-Dynamic Ratio (SDR)
MA
E D
ura
tion
(s) opposite, orthogonal, same
Static component Dynamic component
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ConclusionsConclusions High- and low-velocity channels are adapted separately.High- and low-velocity channels are adapted separately.
Their MAE's show up under different test conditions.Their MAE's show up under different test conditions.(Verstraten et al. ARVO '98)(Verstraten et al. ARVO '98)
Both channels are highly independent.Both channels are highly independent.When we submit them to our new test pattern, no When we submit them to our new test pattern, no
integration takes place; both test components elicit a integration takes place; both test components elicit a separate MAE, resulting in a separate MAE, resulting in a transparent illusory motiontransparent illusory motion..
Varying different parameters, such as direction, speed, Varying different parameters, such as direction, speed, contrast and SDR, has little or no effect on this illusion.contrast and SDR, has little or no effect on this illusion.
Integration of vectors in the MAE only occurs Integration of vectors in the MAE only occurs withinwithin and andnot not betweenbetween the high- and low-velocity channels. the high- and low-velocity channels.
