Abstract
Brightness of an object is determined by spatial context as well as light intensity reflected by the object. A recent study demonstrates that an object's motion can alter brightness of the moving object itself and also brightness of a nearby stationary object (Hong & Kang, 2013). For example, when a dark gray stationary dot is presented with a physically identical moving dot on a white background, the stationary dot appears brighter (brightness shift toward background) and the moving dot appears darker (brightness shift away from the background) than the brightness measured without any motion. In the current study, we investigated how contrast between objects and surrounding uniform background, and contrast between moving and stationary objects affects the motion-induced brightness shift. Brightness of a stationary and a moving dot was separately measured using memory-based choice task, while either the contrast between the dots and the background or the contrast between the stationary and the moving dots was systematically varied. We found that, first, brightness of the stationary dot shifted toward the background and brightness of the moving dot shifted away from the background when contrast between the dots and background was high, consistent with the previous finding. However, when the contrast was low, the direction of brightness shift in the stationary dot was reversed. Second, the magnitude of brightness shift was significantly reduced as a function of the contrast between the stationary and moving dots. We discussed underlying mechanisms mediating the contrast dependent motion-induced brightness shift.
Meeting abstract presented at VSS 2018