1. Dipper function within, but not between, cues for depth and lateral motion Andrew Glennerster, Rob Campbell and Andrew Parker University Laboratory of Physiology, Oxford

2. Lateral motion is easier to detect than motion in depth (Tyler 1971) Left eye Right eye

3. Lateral motion is easier to detect than motion in depth (Tyler 1971) Left eye Right eye

4. Tyler (1971) and Harris and Watamaniuk (1995) Pedestal amplitude (arcmin) Threshold amplitude (arcmin) 00.1110 0.1 0.01 1 10 100 Depth Lateral } Tyler (71) Depth Lateral H & W (95) }

5. Task: which interval contained the signal? Interval #2 lateral pedestal + depth } signal Interval #1 lateral pedestal e.g.:

6. Experimental details Spatial reference separation 30 arcmin bar height 40, width 2 pixel size 0.45 @ 2.65m anti-aliased Temporal target bar oscillated sinusoidally 3 Hz each interval 1 s Psychophysics 2-interval forced choice one signal amplitude per block at least 250 trials per point threshold: amplitude for d = 1 Apparatus Wheatstone stereoscope

7. Detect lat on lateral pedestal Pedestal amplitude (arcmin) Threshold amplitude (arcmin) 00.1110 0.1 0.01 1 10 RAAC Pedestal Ped + lat

8. Detect depth on depth pedestal Pedestal amplitude (arcmin) Threshold amplitude (arcmin) 00.1110 0.1 0.01 1 10 RAAC Pedestal Ped + dep

9. Tyler (1971) and Harris and Watamanuik (1995) Pedestal amplitude (arcmin) Threshold amplitude (arcmin) 00.1110 0.1 0.01 1 10 RAAC 100 Depth Lateral } Tyler (71) Depth Lateral H & W (95) }

10. Normalised thresholds and pedestals Pedestal amplitude normalised by threshold of pedestal Normalised threshold amplitude RAAC lat on lateral ped 10 100 0.1 10 dep on depth ped

11. Detect depth on lateral pedestal Pedestal amplitude (arcmin) Threshold amplitude (arcmin) 00.1110 0.1 0.01 1 10 RAAC Pedestal Ped + dep

12. Detect lat on depth pedestal Pedestal amplitude (arcmin) Threshold amplitude (arcmin) 00.1110 0.1 0.01 1 10 RAAC Pedestal Ped + lat

13. Two subjects Pedestal amplitude (arcmin) Threshold amplitude (arcmin) 00.1110 0.1 0.01 1 10 RAAC 00.1110 JH lat on lat ped dep on dep ped dep on lat ped lat on dep ped

14. Conclusion A dipper function within one domain ( depth with depth pedestal or lat with lateral pedestal) In this case, pedestal and target are processed by the same mechanisms No dipper function for depth with lateral pedestal (and only a small one for lat with depth pedestal) This suggests a lack of interaction between the processing of the two types of motion

15. Normalised thresholds and pedestals Pedestal amplitude (normalised by threshold for pedestal cue) Threshold amplitude (norm. by unmasked threshold) RAAC dep on lateral ped 10 100 0.1 10 lat on depth ped

16. Normalised thresholds and pedestals Pedestal amplitude (normalised by threshold for pedestal cue) Threshold amplitude (norm. by unmasked threshold) RAAC dep on lateral ped 10 100 0.1 10 lat on depth ped norm. by lat thresh lat on lat ped