Obligatory and adaptive averaging in visual short-term memory.

Visual memory can draw upon averaged perceptual representations, a dependence that could be both adaptive and obligatory. In support of this idea, we review a wide range of evidence, including findings from our own lab. This evidence shows that time- and space-averaged memory representations influence detection and recognition responses, and do so without instruction to compute or report an average. Some of the work reviewed exploits fine-grained measures of retrieval from visual short-term memory to closely track the influence of stored averages on recall and recognition of briefly presented visual textures. Results show that reliance on perceptual averages is greatest when memory resources are taxed or when subjects are uncertain about the fidelity of their memory representation. We relate these findings to models of how summary statistics impact visual short-term memory, and discuss a neural signature for contexts in which perceptual averaging exerts maximal influence.