Abstract
A continuous periodic motion stimulus can sometimes be perceived moving in the wrong direction. These illusory reversals have been taken as evidence that part of the motion perception system samples its inputs in a series of discrete snapshots. If so, the precise timing of these snapshots would be critical. We hypothesized that parts of the right parietal lobe (‘When’ pathway) play a critical role in timing perceptual events relative to one another, and thus examined the role of the right parietal lobe in the generation of this “continuous Wagon Wheel Illusion” (c-WWI). Consistent with our hypothesis, we found that the illusion was effectively weakened following disruption of right, but not left, parietal regions by low frequency repetitive transcranial magnetic stimulation. These results were independent of whether the motion stimulus was shown in the left or the right visual field. Thus, the cWWI appears to depend on higher-order attentional mechanisms that are supported by the ‘When’ pathway of the right parietal lobe.