Abstract
Performance on a visual task can be improved when attention is directed to a relevant spatial location or to a specific feature. Spatial attention can be directed either voluntarily (endogenously) or automatically (exogenously). To date, however, feature-based attention has only been shown to operate endogenously. Here, we show that an exogenous feature cue can also lead to improved performance on a visual task.
Response times were measured as participants detected a target oval amongst a circular array of discs, each with a unique color. A colored square cue was flashed at the beginning of each trial immediately before the onset of the search array, that may or may not have matched the location and/or color of the target oval. The location and color of this cue was randomized with respect to the target so that it had no behavioral relevance. As expected, response times were faster when the cue location coincided with the target location, indicating the classic exogenous cueing effect for spatial attention. However, participants also detected the target faster when the color of the cue matched the color of the target regardless of the cue's spatial location. This is evidence of a novel exogenous cueing mechanism for feature-based attention. Response times were fastest when the cue was valid for both spatial location and color, and a 2 × 2 repeated-measures ANOVA with spatial and feature cue validity as main factors showed no significant interaction, indicating that spatial and feature-based cueing mechanisms operate independently and additively on search times. Analysis of performance showed no indication of a speed-accuracy trade off.
Our results suggest that even though exogenous cues capture attention to a particular location, the color feature of the cue still provides a rapid and reflexive exogenous feature-based search benefit at unattended regions of the visual field.