Abstract
Our previous work shows that automatic, perceptual processes and top-down attention interact in a specific and multiplicative manner to alter attentional function (Wager et al., 2015). We found that figure-ground segregation, which requires active neural suppression of the ground region, specifically enhances top-down inhibition of task-irrelevant information. It does not affect top-down facilitation. In the current work, we show that the interaction between ground suppression and top-down inhibition is dynamically modulated by the order in which the two processes are initiated. We measured attentional facilitation and inhibition through performance on a flanker task (Eriksen & Eriksen, 1974). Flanker displays were preceded by a silhouette of an unfamiliar shape. The degree of neural suppression required to segment the image was manipulated by altering the familiarity of the groundside outline (Cacciamani et al., 2015; Peterson et al., 2012). Flanker display elements were positioned such that task-relevant stimuli fell within the figural region of the display and task-irrelevant elements fell into the ground region of the display. Critically, flanker display elements could fall in three locations on the display; on fixation, above fixation or below fixation. If flanker elements fells above or below fixation, participants had to shift attention after the onset of the silhouette. Under these conditions, ground suppression preceded attentional inhibition. As in our previous work, interference from inconsistent flanker items was lower when they fell on familiar (high suppression) ground outlines rather than novel (low suppression) ground outlines. If the flanker elements fells at fixation, however, top-down attention was in place prior to ground suppression. Under these conditions, interference from inconsistent flanker items was higher when they fell on familiar rather than novel ground outlines. We discuss the how the temporal relationship between perceptual and attentional processes might change their function.
Meeting abstract presented at VSS 2018