When facts go down the rabbit hole: contrasting features and objecthood as indexes to memory.

People will often look to empty, uninformative locations in the world when trying to recall spoken information. This spatial indexing behaviour occurs when the information had previously been associated with those locations. It remains unclear, however, whether this behaviour is an example of a simple association across perceptual and cognitive systems, or whether location information plays a role in memory retrieval. In the current study, we investigate whether higher-level cognitive processes, such as object-based attention, are involved in spatial indexing. Participants saw creatures burrowing around the screen, appearing from underground to tell them facts. They saw the same creature in two locations, or two identical creatures in two locations, depending on spatiotemporal cues conveyed by a burrowing animation. While answering questions, we found that participants relied on these spatiotemporal cues, fixating the previous locations of the creature associated with the relevant fact, rather than the location of an identical creature. We interpret these findings in terms of an object-based attentional mechanism that is common to semantic memory and scene perception, and allows 'external memory' to be exploited in a dynamic environment.