Observer reports of the rotating reversals display in the fovea and in the periphery at five different background levels (pixel values: 20, 65, 128, 195, and 255).

The pixel value of 20 made the background darker than the internal rotation grating; values of 65 and 195 made the background near the minimum/maximum of the internal rotation grating; 128 made the background intermediate to the internal rotation grating; and 255 made the background brighter than the internal rotation grating. Observers were asked whether the ring appeared to be rotating counter-clockwise or clockwise, or appeared to remain stationary, or appeared jumbled.