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Stuart Anstis; ‘Zigzag motion’ goes in unexpected directions. Journal of Vision 2009;9(4):17. doi: https://doi.org/10.1167/9.4.17.
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© ARVO (1962-2015); The Authors (2016-present)
In a novel ‘zigzag motion’ display, random dots made alternate long and short jumps, 10 mm downward and 1 mm to the right. The zigs and zags were either at right angles (differing by 90°) or in opposite directions (180°). Result: The perceived direction of motion varied with the viewing distance or spatial scale. During close-up [or distant] viewing the display appeared to move in the direction of the short [or long] jumps. When the motion was stopped after 30 s, a motion aftereffect (MAE) was seen, driven by the short jumps but not the long jumps. Therefore, the perceived direction of motion was dissociated from its aftereffect. A picture rotated alternately 5° clockwise (CW) and 1° counterclockwise (CCW) and appeared to rotate jerkily CW. When stopped, a clockwise MAE was seen, appropriate to the small 1° jumps. If the test field contained blurred, dynamic visual noise, the MAE was now CCW, appropriate to the large 5° jumps; the large jumps drove the perceived motion direction and dynamic MAE, but the small jumps drove the static MAE. Conclusion: Winner-take-all competition between pathways tuned to fast and slow movements. Their independent adaptation gave opposite static and dynamic MAEs.
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