Exploring the Third Dimension of Visual Search

Previous research has suggested that the presence of depth cues may facilitate search performance (e.g., faster RTs for 3-D vs 2-D displays). Here, search arrays were constructed with “T” targets among “L” distractors at two set sizes (18 & 24) at various orientations. To create a percept of depth, 3-D items were rendered with a bevel at three depths and 2-D stimuli were created without a bevel at three sizes to control for a potential size confound. Participants were instructed to search and respond to the presence of a “T” target on each trial – no specific target preview was provided and participants received feedback on every trial. Participants either searched only through 3-D arrays or only through 2-D arrays. The results supported previous findings. Overall, participants in the 3-D condition were faster at detecting the target, but this RT advantage was attenuated as set size increased in target present trials (~217 ms advantage at set size 18 compared to ~61 ms at set size 24). In target absent trials, the RT advantage for 3-D arrays remained intact across set size (~418 ms advantage at set size 18 compared to ~555 ms at set size 24). Accuracy did not differ significantly across the 2-D and 3-D conditions. Overall, these results suggest that the addition of depth may provide a valuable cue for facilitating visual search behavior, but that its utility may diminish as search displays become more complex or cluttered