1. Perceptual grouping in the Ternus display: evidence for an ‘association field’ in apparent motion David Alais & Jean Lorenceau Presented by Nick van der Poel

2. Contents Introduction Experiment 1 and results Experiment 2 and results Experiment 3 and results Experiment 4 and results Conclusion

3. Introduction Ternus displays Contour interactions in apparent motion 4 experiments

4. Stimuli Gabor patches -collinear elements -parallel elements Gaussian blobs

5. Experiment 1 3 observers Contrast of 100%, 50%, 25% mean luminance 7 IFI (27,40,53,67,80,93,107)ms 48 trials at each IFI Measure group motion responses

6. Results experiment 1

7. Experiment 2 Same method as in experiment 1 Fixed IFI of 106 ms and contrast of 100% 2a -> change of interelement distance 2b -> orientation jittering 2c -> phase changes

8. Results experiment 2

9. Experiment 3 Circular display Elements arranged in 60 deg intervals Different IFI’s and contrasts

10. Results experiment 3

11. Experiment 4 Same method as experiment 1 Differing eccentricity

12. Results experiment 4

13. Conclusion The shifting of group motion is as you would expect for association fields Facilitatory grouping in both cases but stronger for the collinear elements