Two Mechanisms of Attention: How Enhancement and Suppression Contribute to Visual Selection

The ability to select and process relevant information quickly and efficiently from a complex visual scene is a hallmark of human vision, and attention is at the core of this ability. The majority of attention research has focused on how attention is allocated to certain information to facilitate processing of the attended information. However, attention is more multifaceted than has been previously recognized. Attention not only facilitates relevant items but it also inhibits irrelevant items. The goal of this body of work is to further understand the inhibitory aspect of attention. Although inhibitory processes have been known as a secondary process that follows attentional selection, recent work shows that inhibitory processes play an active role in attentional selection. This dissertation further argues that attentional suppression is a distinct mechanism from attentional enhancement. Across several experiments, I showed how attentional suppression can be dissociated from attentional enhancement, how the two attentional processes work together to guide attention, and what different attentional consequences they produce. The two processes may interact in deep and interesting ways, but they are still separable and should be considered as two distinct processes