Abstract
Recent research on working-memory (WM) suggests that representations held in WM are not necessarily static representations of past data, but can serve as dynamic representations of expected information. Nobre and Stokes (2019) recently introduced the term “premembering” to describe this proactive role for memory in attention. If true, then it should be possible to dissociate the remembered representation of a previously seen “cue” stimulus from the “premembered” expectation of a future target by statistically manipulating what will happen during search. We asked subjects to search for a target RDK after seeing a “cue” with a specific color and direction of motion (Supplemental S1). The target varied from the cue in predictable ways: one feature dimension (e.g., motion) was drawn from a distribution narrowly centered over the cued feature (low-variance dimension) and the other feature (e.g., color) was sampled from a broad distribution (high-variance dimension). The standard deviation of the low-variance distribution changed over the experiment. In Experiment 1, there were additional “probe” trials on which subjects reported the remembered features of the cue using a color or motion wheel. Analysis of RTs showed that subjects were sensitive to changes in the variance of the low-variance dimension but, probe responses showed WM representations were not sensitive to these changes (S2). Experiment 2 used the same design but “probe” trials asked subjects to predict the target features. This tested whether expectations factor into predictive representations rather than changing the content of memory items. We replicated the RT results from Experiment 1 showing that response-times were sensitive changes in variance, but additionally show that the precision of probe responses changed in step with the variance of the low-variance distribution (S3). These results show a fundamental distinction between how expectations about upcoming sensory data factor into premembered versus remembered representations.