Fig. 2.

Trial timeline showing monocular adaptation for one example condition. At the start of a trial, two sets of nonius lines surrounded by a texture-framed square outlined the target area on each side of the visual field. A grating was then presented to one eye (in this case, the left eye) in order to encourage adaptation to that stimulus while the observer was fixating. After a 100-ms interstimulus interval (ISI), the adapted stimulus was presented again to the same eye, and a different grating was presented to the other eye. In this illustration, red arrows (not present in the actual experiment) show the motion direction of the stimuli. At the end of a trial, a 10-interval, eight-direction judgment scale appeared, and observers recorded their perceptual judgments of motion direction.