Abstract
Purpose: Subjective second-order contours created by abutting stripes can appear to move relative to the texture that creates them. Method: A field of horizontal black/white stripes was bisected by an approximately vertical, wiggly sinusoidal line. To the left of the line the even stripes were black and the odd stripes were white: to the right of the line the opposite was true. A subjective wiggly contour was seen. The whole field now translated downward (eyes were stationary). Result: The wiggly line looked like a necklace of black and white beads that appeared to move downwards, faster than the moving horizontal stripes and overtaking them. Next, a disk of 36 black and 36 white sectors had its central region reversed in contrast (black <—> white). This region was an eccentric circle, but all sectors radiated from the centre of rotation of the main disk. When rotated, the contour of the eccentric little disk appeared to rotate faster than the sectors.