Encoding-specificity instead of online integration of real-world spatial regularities for objects in working memory

In daily life, most objects show high degrees of spatial regularity (e.g., beach umbrellas appear above, not under, beach chairs). Previous studies have shown that spatial regularities of real-world objects benefit visual working memory (VWM), but the mechanisms of this spatial regularity effect remain unclear. This effect can be explained by an “encoding-specificity” hypothesis or a “perception-alike” hypothesis. The former suggests that spatial regularity will enhance the visual encoding process but will not facilitate to integrate information online during VWM maintenance, while the latter suggests that spatial regularity will function in both visual encoding and online integration during VWM maintenance. We investigated whether VWM integrates sequentially presented real-world objects by focusing on the existence of the spatial regularity effect. In five experiments, we first manipulated the presentation (simultaneous vs. sequential) and regularity (with vs. without regularity) of memory arrays among pairs of real-world objects. The spatial regularity of memory objects presented simultaneously, but not sequentially, improved VWM performance. We also examined whether memory load, verbal suppression and masking, and memory array duration hindered the spatial regularity effect in the sequential presentation. However, we found a stable absence of the spatial regularity effect in these experiments, suggesting that participants were unable to integrate real-world objects based on spatial regularities online. Our results support the “encoding-specificity” hypothesis, wherein the spatial regularity of real-world objects can enhance the efficiency of the VWM encoding, but VWM cannot exploit spatial regularity to help organize sampled sequential information into meaningful integrations.