Expectancies about the frequency of a target-similar distractor impact target selection

Abstract

For successful achievement of any task, it is critical to select goal-relevant information while suppressing distractors. Previous research has demonstrated that attentional allocation is biased by a target template that increases the gain of target-relevant features while decreasing the gain of other features. However, it remains unclear how attentional selection and suppression are related when they come into conflict (i.e. when distractors are similar to the target). We investigated this issue with event-related potentials, focusing on the N2pc and Pd components, which are indices of attentional selection and suppression, respectively. A visual search task was used in which the target was defined by a combination of color and shape, and distractors differed from the target in color and/or shape. We manipulated the frequency of a target-colored distractor over blocks, such that the probability of a target-colored distractor was 75% (high-frequency blocks) or 25% (low-frequency blocks). We hypothesized that in high-frequency blocks, participants would decrease the gain on the target color in order to reduce distraction by the frequent target-colored distractors. The results confirmed our hypothesis. Reaction times in the high-frequency block (compared to low-frequency block) were longer to targets that appeared without a target-colored distractor, but shorter when a target-colored distractor was present. Consistent with the behavioral data, the N2pc for the target (without a target-colored distractor) was reduced and the Pd was larger in high-frequency blocks compared to low-frequency blocks. Moreover, the N2pc to the target-colored distractor was smaller and the Pd was larger in high-frequency blocks than in low-frequency blocks. These results indicate that expectancies about target-similar distractors not only impact the ability to suppress them but also affect the ability to select the target. This suggests that feature-based attentional gain was adjusted to maximize the balance between the need to suppress distractors and to select targets. Meeting abstract presented at VSS 2015. Language: en