Figure 4.

Example search arrays and trial events for Experiment 2. There were 32 objects total: 8 red (u’=0.414, v’=0.443, 18.75 cd/m²), 8 blue (u’=0.193, v’=0.259, 18.60 cd/m²), 8 yellow (u’=0.305, v’=0.535, 18.67 cd/m²), and 8 green (u’=0.141, v’=0.510, 18.60 cd/m²), presented on a grey background (39.65 cd/m²). Objects were assigned randomly to locations within a 20.85° × 15.82° region with a minimum inter-item distance of 2.10° and a minimum distance from center of 1.96°. The cue square subtended 0.79° and was composed of four smaller squares each subtending 0.36°. On single-cue trials, all four squares in the cue were the same color; on dual-cue trials, two diagonally opposed squares were presented for each of the two cued colors. Observers began each trial by directing gaze to a central fixation region (1.55°) for 300–500 ms, after which the cue appeared in the center of the screen for 500 ms, beginning 1000 ms prior to search array onset. There was a 1200-ms inter-trial delay.