Working memory capacity modulates Serial dependence in facial Identity: Evidence from behavioral and EEG data

Serial dependence (SD) is said to occur when the judgment of a current stimulus is drawn toward a no longer relevant stimulus from the recent past. Working memory (WM) contributes to the ability to discriminate between irrelevant and relevant sensory impressions. How WM contributes to SD in facial identity remains to be fully understood. In the present study, we used a WM task with varying load interleaved with a facial matching task to investigate the relations between SD in facial identity and WM. EEG was recorded to capture perceptual face processing and WM maintenance. Overall, statistically significant SD effects were obtained only at high WM load. In addition, individual differences in WM capacity predicted SD. Participants with low WM capacity showed significant SD effects regardless of changes in WM load, while participants with high WM capacity showed significant SD only at high WM load. EEG results showed significant differences in perceptual and WM processing for participants with high WM capacity, while no significant differences were obtained for participants with low WM capacity. Neural correlates of WM maintenance, and perceptual processing of a previous face were directly related to SD. The results suggest that WM capacity contributes to SD in facial identity, in terms of selective suppression of task-irrelevant and selective maintenance of task-relevant information.