Proactive suppression and its boundaries: Examining the conditions for successful top-down control

Attention is inherently drawn to distractors with salient physical features, yet it can also be proactively suppressed through top-down control, preventing attentional capture. However, this proactive suppression mechanism can fail under certain conditions. To explore the boundaries of proactive suppression, four experiments were conducted in the present study using the additional singleton paradigm, examining both top-down control and bottom-up factors. In Experiment 1, the singleton-search and feature-search modes were manipulated within subjects. The results revealed a singleton-presence cost in the singleton-search mode but no singleton-presence benefit in the feature-search mode, suggesting that proactive suppression becomes ineffective when search modes are inconsistent. Experiment 2 introduced trial-by-trial variation in targets and singleton distractors, demonstrating that proactive suppression remained effective, indicating its flexibility and rapid deployment. In Experiments 3 and 4, varying levels of singleton distractor salience were examined. The results revealed that proactive suppression was effective for highly salient distractors but failed for low-salience or dynamic distractors. This suggests that proactive suppression requires a certain level of salience and does not extend to dynamic distractors. In conclusion, this study validated the robustness of the proactive suppression mechanism while identifying the conditions under which it fails, shedding light on its operational boundaries. (PsycInfo Database Record (c) 2025 APA, all rights reserved).