The working memory advantage for meaningful stimuli persists under high levels of proactive interference

Previous work has shown that visual working memory performance is higher for recognizable and meaningful stimuli relative to meaningless, but physically matched, stimuli (e.g., Asp et al., 2021). Here, we test whether the benefit for meaningful stimuli arises due to active storage in working memory or can, at least in part, be explained by reliance on more durable memories that persist across trials, such as episodic long-term memory that can substitute for active maintenance. We used ambiguous Mooney faces (Exp. 1, Exp. 3) and objects (Exp. 2) as well as scrambled versions of the same stimuli, resulting in some observers recognizing a given stimulus as meaningful and others not. To manipulate proactive interference, some items were repeated throughout the experiments and others were not. We found equivalent objective and subjective effects of meaningfulness on memory performance regardless of item repetition and thus the amount of proactive interference, consistent with items being actively stored in working memory and providing direct evidence against the idea that durable, cross-trial long-term memories play a critical role in eliciting the meaningfulness advantage. The meaningfulness advantage was strong even with significant proactive interference present. Overall, we find that proactive interference in these tasks is graded, governed by whether items are individuated by spatial or temporal context, and recognition of a stimulus as a face or object provides a strong benefit to working memory performance regardless of the level of proactive interference.