Pre-Activation Dynamics of Category-Specific Attentional Templates in Visual Search

Visual search can be guided and facilitated by a category-specific attentional template (CAT) when searching for a target embedded into a set of categories. While previous research has proven that CATs can be pre-activated, it has caused confusion due to inconsistent task difficulty and unbalanced target-defined dimensions. To avoid the unbalanced dimensions and investigate the effects of category frameworks on the time course of the pre-activation of CAT, we defined the targets as a color-defined category based on prototype (warm, cool), semantic (garden, ocean), and strategy (red–blue, yellow–green). Moreover, to maintain the consistency of task difficulty, we employed the identification task to all frameworks of CAT within the RSPP paradigm and tracked the time course of CAT pre-activation by measuring N2pcs elicited by the probes sequentially occurring prior to the target. ERP and MVPA results found that the semantic-based CAT (involving in experience and learning) was pre-activated first, approximately 1200 ms before the search display, followed by the prototype-based CAT (involving in perceptual similarity) at about 900 ms, and finally the strategy-based CAT (involving in learning) at around 600 ms before the search display. By balancing the target dimensions and maintaining the difficulty of tasks, the findings provide further evidence for differences in the activation patterns of various constitutive CATs.