Abstract
Previous research suggests that subjects are faster and more accurate detecting repeated elements presented unilaterally (both items in the same visual field) versus bilaterally (one item in each visual field). This finding has been explained in terms of an efficient within-field organization process for groups defined by similarity and proximity (Butcher & Cavanagh, 2008). But what about other grouping cues? Here, we examine the cue of closure. On each trial, subjects were presented with four items, each occupying one of four positions defined by left/right x up/down around central fixation. The participants' task was to report whether any two out of four items were the same or whether all four were unique. The repeated target stimuli were square brackets. The distractors were composed by rearranging the line segments of the targets. The repeated brackets occurred in either the same orientation(“[ [ ” no-closure) or mirror reversed orientation ( “[ ]” closure). We found a significant unilateral field advantage in the no-closure condition (12 ms, t(18) = 2.0, p = 0.05), replicating previous work on detecting repetitions presented in the same orientation. However, in the closure condition, we found bilateral repetitions were detected significantly faster than unilateral repetitions (28 ms, t(19)= 3.83 p = 001). These results suggest that closure is more efficiently detected across visual fields versus within a hemifield.