Edges and line minimally mask width discrimination of rectangles

Abstract We studied the effect of various attributes of masking on size discrimination. We show that contrary to the assumptions of many models, observers can accurately compare the width of a test rectangle shown for only 3 ms to the width of a control rectangle shown for 1 s . We also found that masks even one-tenth the size of the test rectangle were as effective as masks twice the size of the test rectangle, and that edges and lines per se were only minimally effective as masks.