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 to ignore or suppress distractors. (2) Methods: Thirty-three undergraduate students completed the Depression Anxiety Stress Scales—21 (DASS-21; Lovibond & Lovibond, 1995) and performed a modified delayed match-to-sample task. Participants encoded abstract shapes under low- or high-perceptual load conditions in visual working memory while ignoring a lateralized Chinese character as task-irrelevant distractor. (3) Results: Individuals with high-state depression, failed to suppress the distractor, evidenced by the absence of early PD. Under low-perceptual load, 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 absence of N2pc. (4) Conclusions: These findings suggest that high-state depression individuals have an impairment 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.