1. CONCLUSIONS * T WO ( SUB ) POPULATIONS OF MOTION SENSORS WITH WITH DIFFERENT CHARACTERISTICS MUST BE RESPONSIBLE FOR THIS DIFFERENCE IN MAE- DIRECTION. * W HERE DO THESE MAE S ORIGINATE ? *...E VEN MORE EXCITING RESULTS WILL BE PRESENTED AT THE ECVP IN O XFORD ( VAN DER SMAGT ET AL. )

2. Universiteit Utrecht The Aftereffect of transparent motion: integration or segregation is determined by the type of test pattern Maarten J. van der Smagt Frans A.J. Verstraten Wim A. van de Grind

3. 0 10 257550 5 15 0 Adaptation Speed (deg/s) MAE Duration (s) Static test Dynamic test Expt. 1 Verstraten et al. (ARVO '98)

4. Expt. 2 Verstraten et al. (ARVO '98) Static test Dynamic test Adaptation Stimulus Static test Dynamic test Adaptation Stimulus

5. Purpose of this study l The low speed channel is tapped by the static test pattern. l The high speed channel is tapped by the dynamic test pattern. è What happens if we construct a test pattern that has both static and dynamic characteristics….

6. è Do both channels interact in the MAE ? è How does this interaction depend on parameters like: è component direction and speed ? è test contrast ? è the relative strength of both static and dynamic components in the test pattern ?

7. Method Adaptation: l Transparent motion, consisting of two components (RPA, 256*256 pixels). è component 1: 1 deg/s (1 pixel/ 4 frames). è component 2: 32 deg/s (8 pixels/ 1 frame). Test: l Test pattern consisting of two components. è component 1: stationary RPA. è component 2: dynamic RPA (refreshed every 2 frames, = 45Hz).

8. Stimuli Component 1Component 2Superimposed space time space time space time ADAPTADAPT space time space time space time TESTTEST

9. Summary of main result orthogonalsameoppositeslow only fast only ADAPTADAPT MAEMAE

10. Parameters l Component direction: è no influence on percept. l Component speed: è as long as both components fall well within only one of the speed tuning curves. l (mean) Test contrast: è no influence on percept. l Ratio of test components (Static-Dynamic Ratio; SDR): è A transparent MAE is perceived, as long as both components are clearly visible in the test stimulus.

11. Results individual components (RAJ) 0.010.1110100 5 10 15 20 25 0 0.010.1110100 5 10 15 20 25 0 0.010.1110100 5 10 15 20 25 0 Static-Dynamic Ratio (SDR) MAE Duration (s) opposite, orthogonal, same Static component Dynamic component

12. Results individual components (TL) Static-Dynamic Ratio (SDR) MAE Duration (s) opposite, orthogonal, same Static component Dynamic component 0.010.1110100 5 10 15 20 0 0.010.1110100 5 10 15 20 0 0.010.1110100 5 10 15 20 0

13. Conclusions l High- and low-velocity channels are adapted separately. è Their MAE's show up under different test conditions. (Verstraten et al. ARVO '98) l Both channels are highly independent. è When we submit them to our new test pattern, no integration takes place; both test components elicit a separate MAE, resulting in a transparent illusory motion. è Varying different parameters, such as direction, speed, contrast and SDR, has little or no effect on this illusion. l Integration of vectors in the MAE only occurs within and not between the high- and low-velocity channels.