Using space to remember: Short-term spatial structure spontaneously improves working memory.

Spatial information plays an important role in how we remember. In general, there are two (non mutually exclusive) views regarding the role that space plays in memory. One view is that objects overlapping in space interfere with each other in memory. For example, objects presented in the same location (at different points in time) are more frequently confused with one another than objects that are not. Another view is that spatial information can 'bootstrap' other kinds of information. For example, remembering a phone number is easier one can see the arrangement of a keypad. Here, building on both perspectives, we test the hypothesis that task-irrelevant spatial structure (i.e., objects appearing in stable locations over repeated iterations) improves working memory. Across 7 experiments, we demonstrate that (1) irrelevant spatial structure improves memory for sequences of objects; (2) this effect does not depend on long-term spatial associations; (3) this effect is unique to space (as opposed to features like color); and (4) spatial structure can be teased apart from spatial interference, and the former drives memory improvement. We discuss how these findings relate to and challenge 'spatial interference' accounts as well as 'visuospatial bootstrapping'.