Figure 2.

Trial structure. Two sample gratings were presented bilaterally at the beginning of each trial and were soon followed by two more gratings. A central cue of “1” or “2” then indicated which pair of gratings was to be retained during the subsequent retention interval. Following retention, a grating was presented in either the left or right position, rotated slightly clockwise or counterclockwise relative to the original sample grating presented in that location; a plaid stimulus appeared in the untested location. Participants indicated the direction of the orientation change within the response period.