Abstract
Recent advancements in understanding attentional suppression through learning have sparked discussions on the underlying mechanisms. A key finding is that interference from salient distractors, like warning signs, significantly diminishes, often falling below baseline levels, when the color of the distractor is consistent and predictable. This finding has been pivotal in shaping the signal suppression framework, which posits that learning reduces specific feature gain, leading to proactive (feature) suppression. Research in this domain often relies on an early lateralized event-related potential known as the PD to investigate whether distractors can be filtered out before capturing attention (i.e., proactively). However, the interpretation of the PD as a marker of proactive suppression has faced challenges, with alternative accounts questioning its accuracy in representing proactive suppression. In a series of EEG experiments, we systematically varied elements of standard designs to explore proactive feature suppression. Across experiments participants performed a feature search variant of the singleton paradigm, wherein the target shape was embedded in a heterogeneous search display, while the distractor color was held constant. In Experiment 1, we observed reliable attenuation of the PD when target features were no longer consistent across trials, a design feature typical for these type of experiments. In Experiment 2 we introduced a sensory imbalance in a neutral, and task-irrelevant display preceding search. This irrelevant display elicited an early PD, even though there was no need for suppression. Experiment 3 demonstrated that color and rotating distractors could be ignored, yet the former elicited a PD, while the latter elicited an N2pc. Together these findings challenge the notion that the distractor PD unequivocally indexes suppression; it reflects the upweighting of target features and can be elicited by displays not requiring suppression. These findings challenge the concept of proactive feature suppression and emphasize the need for a more nuanced PD interpretation.