Fig. 1.

Event-related task paradigm for left (top row) and right (bottom row) hemifields and the corresponding checkerboard stimuli. The stimuli comprised two radial checkerboards separated by a fixation cross. To introduce delay in the onsets or the stimulus onset asynchrony (SOA), the left hemifield stimulus was presented d ms before the right. The SOA, d ranged from 0 to 112 ms (including 0, 28, 56, 84 and 112 ms) in steps of 28 ms, which was twice the time between screen refreshes of the projector.