Learned feature regularities enable suppression of spatially overlapping stimuli

Contemporary theories of attentional control state that information can be prioritized based onselection history. Even though theories agree that selection history can impact representations ofspatial location, which in turn helps guide attention, there remains disagreement on whether nonspatial features (e.g., color) are modulated in a similar way. While previous work hasdemonstrated color suppression using visual search tasks, it is possible that the locationcorresponding to the distractor was suppressed, consistent with a spatial mechanism ofsuppression. Here, we sought to rule out this possibility by testing whether similar suppression ofa learned distractor color can occur for spatially overlapping visual stimuli. On a given trial, twospatially superimposed stimuli (line arrays) were tilted either left or right of vertical andpresented in one of four distinct colors. Subjects performed a speeded report of the orientation ofthe ‘target’ array with the most lines. Critically, the distractor array was regularly one color, andthis high-probability color was never the color of the target array, which encouraged learnedsuppression. In two experiments, responses to the target array were fastest when the distractorarray was in the high-probability color, suggesting participants suppressed the distractor color.Additionally, when regularities were removed, the high-probability distractor color continued tobenefit speeded target identification for individual subjects (E1), but slowed target identification(E2) when presented in the target array. Together these results indicate that learned suppressionof feature-based regularities modulates target detection performance independent of spatiallocation and persists over time.