[Effect of task demand on the allocation of attention in a large three-dimensional space]

This study investigated the effect of task demand on the allocation of attention in a large three-dimensional (3-D) space. Two load conditions were conducted. In the low load condition, the observer was required to judge whether a target appeared nearer or further than the fixation point. In the high load condition, the observer was also required to judge whether the target appeared at the same position as the fixation point. Pre-cues, which indicated the spatial location of a target, were used in order to control attentional shifts in depth. There were three conditions about cue validity: valid, invalid and neutral conditions. The results indicated that the effect of cue validity was more significant in the high load condition. Furthermore, the attentional effect (the difference between invalid and valid conditions) changed with regard to the target position in the high load condition, but remained unchanged in the low load condition. This suggests that attentional allocation can be changed depending on the task demand in a large 3-D space.