Tudor Domain

striped moving pattern, then when the motion is stopped the stripes appear to move back in the opposite direction. This motion aftereffect can be built up to one eye and elicited from the other eye. Murakami aimed an annular stimulus containing drifting stripes at the blind spot of the right eye. Filling-in made this look like a complete striped disk. He then tested with a small striped disk, smaller than the hole in the annulus, and viewed by the corresponding intact retina of the left eye. Observers reported a motion aftereffect. This suggests that the motion was actively filled into the blind spot of the right eye. Further support comes from fillingin of a large disk. A large white disk was flashed up on a black surround, followed 50–100 milliseconds later by a white outline circle of about half the diameter. Observers reported that the interior of the outline circle looked black. If the circle was smaller, the optimal time gap was longer. This suggests that a brightness signal propagates inward from the circumference at an estimated speed of 110–150° of visual angle per second, and is arrested by the barrier of the outline circle. This is supported by experiments on simultaneous contrast. A static grey disk appears to brighten and dim when its surround respectively dims and brightens, but this process breaks down at repetition rates exceeding 2.5 Hz, suggesting also a spreading process at a finite speed. Similar effects have been shown for the filling-in of texture.