Poster Session A, Saturday, March 23, 1:30 pm - 3:30 pm, Pacific Concourse
The time-course of component processes of selective attention
Tanya Wen1,2, John Duncan1,2, Daniel Mitchell1,2; 1MRC Cognition and Brain Sciences Unit, 2University of Cambridge
Attentional selection shapes human perception, enhancing relevant information, according to behavioral goals. Here, we used multivariate decoding of electrophysiological brain responses (MEG/EEG) to examine real-time representation of the component processes of selective attention. Auditory cues instructed participants to respond to a particular visual target, embedded within a stream of single- and multi-item displays. Although the task logically required items to be compared to an attentional “template”, signals consistent with such a template were relatively weak and appeared to transition through an active sensory format before becoming quiescent. Subsequent stimulus processing evoked strong neural representation of multiple target features, evolving over different timescales. Combining single and multi-item displays with different types of distractors, allowed quantification of various components of attention. Following a visual choice display, we observed five distinguishable processing operations with different time-courses. First, visual properties of the stimulus were strongly represented. Second, the location of the candidate target was rapidly represented in multi-item displays, providing the earliest evidence of modulation by behavioral relevance. Third, biased competition continued to enhance the representation of the candidate target, including its identity, relative to distractors. Fourth, only later was the behavioral significance of the target explicitly represented in single-item displays. Finally, if the target was not identified and search was to be resumed, then an attentional template was weakly reactivated. The observation that an item’s behavioral relevance directs attention in multi-item displays prior to explicit representation of target/non-target status in single-item displays is consistent with two-stage models of attention.
Topic Area: ATTENTION: Spatial