Two luminance gratings of identical orientation and opposite directions of motion are seen as moving across one another (i.e. moving transparently) only if they differ in spatial frequency (SF) by a factor of four or more. Identical SF gratings produce counter-phase flicker. This suggests that opposite motions cancel each other at the level of motion detection. Here we show that motion transparency is perceived with two gratings of the same SF and orientation moving in opposite directions, when one grating is a first-order, luminance modulated (LM) stimulus and the other is a second-order, contrast modulated (CM) stimulus.
- motion transparency
- vision sciences