Spatial cuing in a stereoscopic display: Evidence for a "depth-aware" attentional focus

Two experiments were conducted to explore whether attentional selection occurs in depth, or whether attentional focus is "depth blind," as suggested by Ghiradelli and Folk (1996). In Experiment 1, observers viewed stereoscopic displays in which one of four spatial locations was cued. Two of the locations were at a near-depth location and two were at a far-depth location, and a single target was presented along with three distractors. The results indicated a larger cost in reaction time for switching attention in x, y and depth than in x, y alone, supporting a "depth-aware" attentional spotlight. In Experiment 2, no distractors were present, similar to the displays used by Ghiradelli and Folk. In this experiment, no effect for switching attention in depth was found, indicating that the selectivity of attention in depth depends on the perceptual load imposed on observers by the tasks and displays.