Figure 1.

Stimulus used to generate afterimages. The yellow labels indicate degrees eccentricity from the center of the diamond configuration. The outermost white dots are markers used to calibrate the eye tracker. The four grayish tabs on the edges of the board are infrared markers used by the EyeLink to track head position. After calibration, the infrared camera of the eye tracker continued to function without visible light. A red, fixation dot (a laser pointer), aligned to the center of the diamond shapes, directed the observer's gaze to the center of the image. The stimulus was briefly illuminated to create an afterimage, and the red dot was extinguished. Observers were then asked to look at a specific corner of the diamond afterimage, to report if they succeeded and whether they saw any motion of the image. In some conditions they were then asked to make a saccade to the center of the lower X.