Pattern cues disambiguate perceived direction in simple moving stimuli

Much of our knowledge about motion perception has been obtained by studying bars moving within apertures. When viewed within an ambiguously oriented aperture such as a circle, bars appear to move orthogonal to their orientation. We demonstrate that if the local orientation of the aperture edges is altered, a direction consistent with the edge orientation is seen. Indeed, the perceived direction can be strongly influenced by static lines separated from the edge of the moving stimulus. These results support recent suggestions that precise motion direction is likely to be determined by static orientation cues.