Figure 3.

Double-Drift Resets. Left: At some point, the perceived position may stop moving further away from its actual path. For some people this takes the form of a “return” reset, back toward the true position either suddenly or slowly, for others it means the illusory position remains at a fixed offset moving parallel to the real path. Right: Given varying strength of the illusion (denoted by the angle of the purple arrows), e.g. due to stimulus properties or within or between subject differences, resets may occur at different points in space. Top right: if these resets can be explained by a spatial limit on the size of the illusory position shift away from the true vertical path, the locations of the resets should have a constant X coordinate; the spatial offset from the vertical path. Bottom right: if they occur instead after some period of time, resets should have a constant radius (T); the time since the Gabor's motion began.