Abstract
The processing of a visual object can be systematically biased towards an object that was processed several seconds ago. This phenomenon, called serial dependence, has been thought to promote an object’s stability by compensating for small changes of its appear-ance over time. Up until now, it has been debated whether this attractive bias occurs at perceptual or post-perceptual levels of the processing hierarchy. To address this issue, we recorded neuronal activity using MEG while participants remembered motion directions of two sequentially presented red and green items. After a delay, a colored retro-cue indicated the item whose motion direction participants had to report. We observed that the currently reported motion direction was biased toward the item retro-cued on the previous trial. This bias was present when the current and the previous item's motion directions were similar to each other and further increased when items shared the same color. This replicated our recent results (Fischer et al., 2020). Using an inverted encoding model, we could reconstruct the motion direction from the MEG signal of both items in the current trial. The reconstruction was perfectly aligned to the actual motion direction at time-points when the corresponding item was presented and memorized. Our preliminary analyses also showed that after the retro-cue, the reconstructed signal was slightly shifted towards the direction of the item retro-cued in the previous trial. This suggests that serial dependence operates when an item is accessed in working memory rather than when it is perceived or memorized.