The effects of grouping search elements by depth on target selection
56.544, Tuesday, May 14, 2:45 - 6:45 pm, Vista Ballroom
Nonie Finlayson1, Roger Remington1, James Retell1, Philip Grove1; 1Schoolf of Psychology, The University of Queensland
Previous research has shown that while the number of elements in a search display affects the time to find a target, search can be more efficient if targets contain a unique feature, such as a particular colour, that can either be detected in parallel or can be used to confine search to elements with that property (Egeth, Virzi, & Garbart, 1984). Our study examined whether the effects of distracting elements could be similarly reduced by segmenting a conjunction search across two depth planes. Three important empirical findings emerged. First, we found evidence for parallel search when the target was a feature singleton on one depth plane, but a conjunction search given distractors on the non-target plane. This result indicates that parallel search is possible on an attended depth plane. Second, benefits of segmentation in depth were only observed when the target depth plane was known in advance. This result indicates that, unlike colour, segmentation in depth does not afford parallel access to information on separate depth planes. Third, no benefit of segmentation in depth was observed when both depth planes required serial search. This result can be accounted for by assuming that the act of attending to a depth plane draws on the same attentional processes required for serial search within a depth plane. We conclude that segmentation into two depth planes can facilitate visual search, but unlike colour or other elementary properties, does not provide an automatic, pre-attentive segmentation.