The Motion Bridging Effect (MBE) is an illusion in which a motion that is not consciously visible generates a visible motion aftereffect that is predominantly in the same direction as the adapter motion. In the initial study of the MBE (Mattler & Fendrich, 2010), a ring of 16 points was rotated at angular velocities as high as 22508/s so that observers saw only an unbroken outline circle and performed at chance when asked to report the ring's rotation direction. However, when the rotating ring was replaced by a veridically stationary ring of 16 points, the stationary ring appeared to visibly spin to a halt, principally in the same direction as the initial ring's rotation. Here we continue to investigate the stimulus dependencies of the MBE. We find the MBE, measured by the correspondence between the direction of the invisible rotation of the spinning ring and perceived rotation of the stationary ring, increases as the number of points used to construct the rings decreases and grows stronger as the diameter of the rings get larger. We consider the potential contributions of temporal frequency, retinal eccentricity, luminance levels, and the separation between the points forming the rings as mediators of these effects. Data is discussed with regard to the detection of real movement and apparent motion. We conclude that the detection of the rapid rotation of the spinning ring is likely to be modulated by temporal frequency of luminance changes along the ring perimeter while the point-distance may modulate an apparent motion produced by the transition from the perceptually unbroken spinning ring to the point-defined stationary ring.

A ring of points that is rotated so rapidly is perceived as a stationary outline circle that can induce an illusory rotation with the same spin direction in a subsequently presented ring of stationary points. This motion bridging effect (MBE) demonstrates that motion information can be conveyed by temporal frequencies generally thought to exceed the processing capabilities of the human visual system. It was first described in displays shown with an analog oscilloscope, but the rapid rotation rates needed to produce the MBE have heretofore prevented it from being investigated with conventional raster scan monitors. Here, we demonstrate the MBE can be reliably generated using the new generation of 240 Hz LCD gaming monitors, and exhibits basic characteristics similar to those reported previously. These monitors therefore provide a readily available resource for research on the MBE and the studies of the visual processing rapid motions in general.

We report a novel visual illusion we call the Ring Rotation Illusion (RRI). When a ring of stationary points replaces a circular outline, the ring of points appears to rotate to a halt, although no actual motion has been displayed. Three experiments evaluate the clarity of the illusory rotation. Clarity decreased as the diameter of the circle and ring increased and increased as the number of points forming the ring increased. The optimal interstimulus interval (ISI) between the circle and ring was 90 ms when stimulus presentations lasted 100 ms but 0 ms with 500 ms presentations. We compare the RRI to the Motion Bridging Effect (MBE), a similar illusion in which a stationary ring of points replaces an initial ring of points that spins so rapidly it looks like a stationary outline. A rotation of the stationary ring is seen that usually matches the direction of the initial ring’s invisible spin. Participants reported a slightly more frequent and clearer motion percept with the MBE than RRI. ISI manipulations had similar effects on the two illusions, but the effects of number of points and ring diameter were largely restricted to the RRI. We suggest that both the RRI and MBE motion percepts are produced by a visual heuristic that holds that the transition from an outline circle to a ring of points is plausibly explained by a rapid spin decelerating to a halt, but in the case of the MBE, an additional direction-sensitive mechanism contributes to this percept.

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