Average size perception and the allure of a new mechanism

In this brief response to commentaries by Ariely (2008) and Chong, Joo, Emmanouil, and Treisman (2008) on our earlier article, we highlight the two key assumptions underlying earlier claims about statistical summary representations of object size and argue that existing studies have not met either of them. We note why statistical summary representations of size are different from such representations of motion or orientation, and we emphasize the need for simulations of performance to exclude focused attention explanations for judgments of average size.