Park Hyung-Bum, Awh Edward
Institute for Mind and Biology, University of Chicago.
Department of Psychology, University of Chicago.
bioRxiv. 2025 Jul 10:2025.07.07.663569. doi: 10.1101/2025.07.07.663569.
Visual working memory (WM) capacity has recently been claimed to be higher for meaningful objects compared to simple visual features, possibly due to richer and more distinctive representations. However, prior demonstrations of this advantage have typically compared performance with meaningful stimuli that are trial-unique to performance with a small set of repeated simple stimuli (e.g., colors). This design creates a confound between the strength of proactive interference (PI) and meaningfulness, such that PI is minimized for meaningful items compared to colors. Thus, improved WM performance with meaningful objects could reflect enhanced contributions from episodic long term memory (LTM), a memory system that is highly vulnerable to PI, rather than an increase in WM capacity. To examine this issue, Experiment 1 measured WM capacity for repeated colors, repeated meaningful objects, and trial-unique meaningful objects. We replicated the previously observed advantage for trial-unique objects over colors. Critically, this advantage was eliminated entirely with repeated meaningful objects that equated PI across the meaningful and simple stimuli, suggesting that minimal PI, not meaningfulness, drove this behavioral effect. In line with this hypothesis, hierarchical Bayesian dual-process signal detection modeling suggested that the advantage for trial-unique objects was due to enhanced familiarity-based LTM signals rather than recollection-based WM processes. To directly measure online storage in WM, Experiment 2 measured contralateral delay activity (CDA), an electrophysiological marker of the number of items stored in working memory. Although we saw the typical performance benefits for trial-unique objects over repeated colors, CDA activity across increasing set sizes revealed a common plateau for trial-unique meaningful objects and repeated colors, indicating a WM storage limit that is independent of stimulus meaningfulness. Thus, past demonstrations of superior memory performance with meaningful stimuli can be explained by a task design that minimized PI for meaningful compared to simple stimuli. When PI is equated, WM storage limits for simple and meaningful stimuli are equivalent.
最近有人声称，与简单视觉特征相比，有意义物体的视觉工作记忆（WM）容量更高，这可能是由于其表征更丰富、更独特。然而，此前关于这一优势的论证通常是将对试验独特的有意义刺激的表现与对一小组重复简单刺激（如颜色）的表现进行比较。这种设计在 proactive interference（PI）强度和意义之间造成了混淆，使得与颜色相比，有意义项目的PI被最小化。因此，有意义物体的WM表现改善可能反映了情景长期记忆（LTM）的增强贡献，LTM是一个极易受到PI影响的记忆系统，而不是WM容量的增加。为了研究这个问题，实验1测量了重复颜色、重复有意义物体和试验独特有意义物体的WM容量。我们重现了之前观察到的试验独特物体相对于颜色的优势。关键的是，当有意义和简单刺激的PI相当时，这种优势在重复有意义物体的情况下完全消失了，这表明是最小的PI而非意义驱动了这种行为效应。与这一假设一致，分层贝叶斯双过程信号检测模型表明，试验独特物体的优势归因于基于熟悉度的LTM信号增强，而非基于回忆的WM过程。为了直接测量WM中的在线存储，实验2测量了对侧延迟活动（CDA），这是工作记忆中存储项目数量的电生理指标。尽管我们看到了试验独特物体相对于重复颜色的典型表现优势，但随着集合大小增加，CDA活动显示试验独特有意义物体和重复颜色有一个共同的平稳期，这表明WM存储限制与刺激意义无关。因此，过去关于有意义刺激具有卓越记忆表现的论证可以通过一种任务设计来解释，这种设计使得有意义刺激相对于简单刺激的PI最小化。当PI相当时，简单和有意义刺激的WM存储限制是相等的。
