Poster D7, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Flexible biasing of visuospatial attention works through both target facilitation and distractor suppression
Kerstin Unger1, Rebecca Waugh1, Michael S. Worden1; 1Brown University, Department of Neuroscience
Preparatory spatial attention may improve processing of stimuli in attended locations (target facilitation) while attenuating processing of stimuli in unattended locations (distractor suppression). Recent work suggests that different neural mechanisms underlie target facilitation and distractor suppression. Specifically, mechanisms of target facilitation may be flexible and goal-directed, while distractor suppression mechanisms are not. However, most previous studies did not account for feature-based attention in target selection, potentially underestimating the role of preparatory suppression of distractor locations. Here, we controlled for feature-based target selection using an explicit spatial cueing paradigm that systematically varied the degree of feature overlap between target and distractor stimuli. Cue types occurred in blocks and indicated either target location, distractor location, or were uninformative. Target and distractor locations varied randomly with each trial. Participants responded faster to target and distractor cues, compared to uninformative cues. However, we found lateralized alpha-band activity, a potential electrophysiological correlate of preparatory suppression of anticipated distractors, only in target cueing. Both target and distractor cueing were associated with an enhancement of P1 amplitude to the target stimuli. The N1 amplitude to distractor stimuli was enhanced following target cues, but reduced following distractor cues. The lack of lateralized alpha-band activity in the distractor condition suggests that it is difficult to deploy targeted suppression in response to an attention-directing cue. However, P1 and N1 amplitude changes following distractor cues may indicate that distractor suppression mechanisms operate in a reactive fashion and are more flexible and goal-directed than previously thought in facilitating spatially specific processing.
Topic Area: ATTENTION: Spatial