Abstract
Here we present an original illusion in which polarity reversing, stationary Craik-O'Brien-Cornsweet stimuli viewed under maintained fixation appear to move with dramatic unpredictable trajectories. Some stimulus configurations can lead to significant distortions of shape. For example, in addition to appearing to wander across the screen, a polarity reversing circle may appear to continuously deform such that it appears like an oval or even a polygon. Both the distortions and global motion largely arise from the distribution of local motion signals that are generated along the polarity-reversing contour. For example, a polarity reversing Cornsweet line may appear to move in either of the directions orthogonal to its contour and does not appear to deform. Whereas a pattern reversing circle, which has local motion pointing in all directions, may appear to wander aimlessly across the screen and deform in any number of ways. These effects appear to be strongest when stimuli are viewed peripherally, and polarity reversals occur at a rate 8-12 Hz. These effects are greatly reduced for non-Cornsweet stimuli, such as a light and dark line side by side, or a unipolar Gaussian contour.
Meeting abstract presented at VSS 2014