Abstract
1. A coarse vertical grating drifts to the right behind a screen that is pierced with numerous small, randomly placed stationary round holes, like a Swiss cheese. The holes are one grating period in diameter. Result: When the screen is mid-grey, the motion is clearly seen; the holes themselves seem to drift to the right; and stopping the motion yields a strong leftward motion aftereffect. But when the screen is black, little or no motion, nor motion aftereffect, is seen; and the holes do not budge. In short, the black screen appears to silence the motion. Conclusion: The mid-grey screen “crispens” the grating, increasing its perceived contrast and hence motion salience. 2. A large hole and a fine grating behind it, move in synchrony to the right, like a disk painted with stripes. On a black surround, the stripes are correctly seen in step with the disk. But on a black/white flickering surround, the stripes appear to overtake the disk and move at twice its speed. Conclusion: Reverse phi apparently slows the disk, but not the stripes it contains.
Meeting abstract presented at VSS 2015