The Impact of State Depression on Proactive Control and Distractor Processing in a Memory Task: An Electrophysiological Study

(1) Background: Individuals with high levels of state depression are hypothesized to have an impairment of attentional control functions necessary for filtering irrelevant information. This study used the event-related potential of early PD, a marker of distractor suppression, and N2pc, an indicator of attentional capture to investigate whether high state depression affects selective attention in ignoring or suppressing distractors. (2) Methods: Thirty-three undergraduate students completed the Depression Anxiety Stress Scale-21 (DASS-21) and performed a modified, delayed match-to-sample task. Participants encoded abstract shapes under low or high perceptual load conditions in the visual working memory while ignoring a lateralized Chinese character as a task-irrelevant singleton distractor. (3) Results: Individuals with high state depression failed to suppress the distractor, as evidenced by the absence of early PD. Under low perceptual loads, they also displayed a significant N2pc component, indicating attentional allocation to the distractor. In contrast, low-state-depression participants successfully suppressed the distractor, showing early PD and the absence of N2pc. (4) Conclusions: These findings suggest that high-state-depression individuals have an impairment in top–down attentional control, particularly in feature-based selective attention. This deficit hinders the ability to filter out irrelevant information, potentially contributing to cognitive difficulties associated with depression.