The perceptual average in ensemble representation: Neither perceptual nor an average

This report targets the claim that gist representations of visual stimuli, called "ensemble averages", are perceptual representations of statistics pertaining to stimuli. We report predictions of a mathematical model based on classical memory architectures which assumes ensemble averages are statistical approximations to stimuli, and that those approximations are constructed within short-term memory. We report results of three new experiments that test those predictions. The results support the memory model and contradict the view that representations of ensemble averages are computed early in perceptual processing via parallel processing or neural pooling, suggesting instead that they are computed via control processes acting on item representations held in visual short-term memory. We conclude that the flight toward new mechanisms that has occurred within the ensemble representation literature is ill-advised, and suggest that one first carefully consider what well-established memory models can accomplish in the ensemble "perception" domain.