Real-world objects are not stored in holistic representations in visual working memory

When storing multiple objects in visual working memory, observers sometimes misattribute perceived features to incorrect locations or objects. These misattributions are called binding errors (or swaps) and have been previously demonstrated mostly in simple objects whose features are easy to encode independently and arbitrarily chosen, like colors and orientations. Here, we tested whether similar swaps can occur with real-world objects, where the connection between features is meaningful rather than arbitrary. In Experiments 1 and 2, observers were simultaneously shown four items from two object categories. Within a category, the two exemplars could be presented in either the same or different states (e.g., open/closed; full/empty). After a delay, both exemplars from one of the categories were probed, and participants had to recognize which exemplar went with which state. We found good memory for state information and exemplar information on their own, but a significant memory decrement for exemplar-state combinations, suggesting that binding was difficult for observers and “swap” errors occurred even for meaningful real-world objects. In Experiment 3, we used the same tasks, but on half of the trials, the locations of the exemplars were swapped at test. We found that participants ascribed incorrect states to exemplars more frequently when the locations of exemplars were swapped. We concluded that the internal features of real-world objects are not perfectly bound in working memory, and location updates impair the object representation. Overall, we provide evidence that even real-world objects are not stored in an entirely unitized format in working memory.

在视觉工作记忆中存储多个物体时，观察者有时会将感知到的特征错误地归因于不正确的位置或物体。这种归因错误（或称互换）在先前的研究中主要是在简单物体中观察到，这些物体的特征易于独立且任意地编码，如颜色和方向。在本研究中，我们测试了类似的互换是否会在现实世界物体中发生，在这些物体中，特征之间的联系是有意义的而非任意的。在实验1和2中，观察者同时展示了两个物体类别中的四个物品。在类别内部，两个示例可以以相同或不同的状态呈现（例如，开启/关闭；满/空）。在延迟之后，其中一个类别中的两个示例被探测，参与者需要识别哪个示例与哪个状态相匹配。我们发现对于状态信息和示例信息本身有良好的记忆，但对于示例-状态组合的记忆显著下降，这表明对于观察者而言，绑定是困难的，甚至在有意义的现实世界物体中也发生了“互换”错误。在实验3中，我们使用了相同的任务，但在一半的试验中，在测试时交换了示例的位置。我们发现，当示例的位置被交换时，参与者将不正确的状态归因于示例的频率更高。我们得出结论，现实世界物体的内部特征在工作记忆中并未完全绑定，位置更新损害了物体表征。总的来说，我们提供了证据，即即使是现实世界物体在工作记忆中也不是以完全统一的形式存储。