The interaction between feature- and space-based attention

Although the separate effects of feature- and space-based attention are relatively well established, the conjoint effects of attending to both a location and a feature are under-investigated. I analyzed the literature and extracted three approaches that explain such conjoint effects, namely the independence, sensory gating, and boosting approaches. The three approaches have substantial supports and shortcomings, and the current study will investigate which of the three approaches provide the best prediction of behavioral performance. I conducted two experiments to investigate whether the interplay between feature- and space-based attention varied as a function of the elapsed time between the cue and the target onset. A space-feature combination cue directed attention to a target on which participants discriminated small changes in color saturation. Both the spatial and feature cues were partially valid, making it possible to assess the cueing effect. The time difference between the cue and the saturation change onsets was manipulated in fine steps. Experiment 1 showed that space- and feature-based attention had an interactive effect on performance, such that feature-based attention did not influence performance outside the focus of space-based attention regardless of the temporal asynchrony between the cue and target onset. Experiment 2 was conducted to determine which of the three approaches provided the best account for the interaction pattern by adding a spatially neutral condition. It showed that feature- and space-based attention influenced performance, yet feature-based attention could not influence the performance outside the focus of spatial attention regardless of the temporal asynchrony between the cue and target onset. Moreover, the effectiveness of feature-based attention was equivalent at the spatially valid and neutral locations. In conclusion, the findings resemble with the predictions of the sensory gating approach. While feature-based attention could operate at the attended location or under diffused spatial attention equally well, its effectiveness diminished outside the focus of spatial attention. Moreover, the spatial filter imposed on feature-based attention is more permeable than originally proposed by the sensory gating approach. Lastly, feature-based attention does not fully spread to an unattended location regardless of the time difference between the cue and target onsets.