Rapid and reflexive feature-based attention.

Performance on a visual task is improved when attention is directed to relevant spatial locations or specific visual features. Spatial attention can be directed either voluntarily (endogenously) or automatically (exogenously). However, feature-based attention has only been shown to operate endogenously. Here, we show that an exogenous cue to a visual feature can lead to improved performance in visual search. Response times were measured as subjects detected or discriminated a target oval among an array of disks, each with a unique color. An uninformative colored cue was flashed at the beginning of each trial that sometimes matched the location and/or color of the target oval. Subjects detected or discriminated the target faster when the color of the cue matched the color of the target, regardless of the cue's location relative to the target. Our results suggest evidence for a previously unknown exogenous cuing mechanism for feature-based attention.