Abstract
Serial dependence refers to a systematic bias that attracts present towards recent visual inputs. It has been assumed to increase the stability of perception, as most recent and attended input has the strongest bias. Recent studies have suggested that serial dependence is a mnemonic rather than a purely perceptual phenomenon, as it increases with longer memory periods. However, studies so far have required memorizing only a single item at a time. Hence, it remains unclear which factors besides temporal proximity influence serial dependence when multiple items are encoded into working memory. One possibility is that attraction could be tuned by factors that relate items to one another across trials. To examine this issue, we asked 49 young adults to encode and remember two sequentially presented stimuli (S1 and S2) per trial. They were random dot kinematograms (RDKs) with different directions, one of which was retrocued and had to be reported via continuous recall. In addition, RDKs were shown in either red or green, whereby color was task-irrelevant. Hence, across trials items could be related either by their corresponding serial position (e.g., previous with current S1) or by color similarity (e.g., previous and current green stimulus). Consistent with the literature we observed a clear attractive bias for the reported item toward the items presented in the previous trial. Importantly, serial dependence was enhanced for items with congruent serial position, i.e., the current S1 was attracted more strongly to the previous S1 than previous S2, and S2 was biased more strongly toward the previous S2 than previous S1. In contrast, color congruency did not modulate serial dependence. These findings indicate that task-relevant contextual information relates items across memory episodes and thus determines serial dependence in addition to temporal proximity.
Meeting abstract presented at VSS 2018