The Role of Attention in Visual Processing

The first aftereffect concerned adaptation of the Schroder staircase, which is a reversible perspective figure like the Necker cube. If one adapts to an unambiguous version of the staircase, biased towards one perspective, the ambiguous figure appears in the opposite perspective. During the adaptation phase, I superimposed two unambiguous adapting staircases in opposing perspective. Both staircases were centered on fixation and were of different sizes and colors to increase their discriminability. During the adaptation phase, color changes were occasionally introduced in the transverse line segments that defined the steps of each staircase. These color changes were brief 100 ms and occurred randomly about the fixation point. In different blocks of trials, subjects detected the color changes in one or the other staircase. Following the adaptation phase, subjects judged the perceived perspective of the ambiguous test staircase. The basic result is that the test staircase is seen in the perspective opposite the task relevant staircase. sdw