Abstract
Purpose: Visual attention can select locations, features, and objects. However, the relative contributions and the interactions among these selection mechanisms are less clear. One issue concerns the relative effectiveness of these mechanisms, which has been difficult to compare, given the different nature of the studies in the literature. Here we tested the effectiveness of space- and feature- based orienting in a single experiment with identical stimuli and task.
Method: Moving dot patterns were presented in two apertures, one to the left and one to the right of fixation. Within each aperture, two superimposed dot patterns moved in opposite directions (leftward and rightward). On different trials, all dot patterns either moved at constant speeds or one dot pattern increased its speed briefly. Observers detected the presence of the speed increment (target), which appeared on half of the trials. Arrow cues were presented briefly 500 ms prior to the dot patterns. Cues pointed either to the left, to the right, or both directions (neutral). In separate blocks, the unidirectional cues either indicated the location or the direction of the target with a 100% validity. Attentional effect was measured as the performance difference between the unidirectional cues and the neutral cue.
Results: Compared to the neutral cues, both the location and direction cues increased detection rate (d'). Furthermore, the attentional benefit for the two types of cues was equivalent. These results suggest that attention is a flexible mechanism allowing us to efficiently select task-relevant information based on either spatial or feature dimensions.