Distinct underlying mechanisms contribute to learning-dependent distractor rejection.

The signal suppression hypothesis has been proposed as an explanation for why physically salient stimuli sometimes involuntarily draw attention and other times can be successfully ignored. Recent accounts of signal suppression, and learning-dependent distractor rejection more broadly, offer conflicting findings concerning the extent to which facilitated ignoring of a salient distractor is feature specific or feature general. The present study provides evidence for concurrent learning-dependent gains in feature-specific distractor rejection, which is sensitive to stimulus frequency and relatively short-lived, and feature-general distractor rejection, which builds from experience rejecting salient stimuli and is more enduring. On the first day of testing, participants were facilitated in ignoring salient distractors presented in a high-probability location and rendered in a high-probability color, which produced additive benefits, and were simultaneously better able to ignore salient distractors in general (including low-probability distractors) with practice. Critically, while the effects of the biased probabilities were no longer evident on the second day of testing in which these probabilities were equated, the effect of practice on ignoring remained and generalized to novel distractors. Together, these findings suggest that distinct underlying mechanisms capable of concurrently influencing information processing collectively give rise to the ability to more efficiently ignore salient distractors with experience.