Figure 4.

Displays and results of Experiment 3A. The top panel illustrates sample trials of the spatial subset search task and the standard search task. In the spatial subset search task, observers knew that the target would appear in the middle ring of the display. There were additional foil targets in the other rings to further encourage observers to focus on the middle ring. Placeholders also appeared on the midlines during the precue and test display in order to enhance the spatial-filtering demands. In the standard search, precues alerted the participant to the locations that would be task relevant, but no irrelevant items or placeholders were ever presented. The bottom panel shows reaction time (ms) versus set size for correct responses on each task. Error bars show within-subject standard error of the mean. (a) In the spatial subset visual search task, reaction times are longer in the unilateral condition than in the bilateral condition, with a reliable difference emerging at set size 4. (b) In the standard visual search task, there was no difference between unilateral and bilateral displays.