A selective summary of visual averaging research and issues up to 2000.

Ariely's (2001) "Seeing Sets: Representation by Statistical Properties" (Psychological Science, 12, 157-162) rekindled interest in summary-value estimation for visual ensembles (groups of similar items). Revisiting and reinvigorating research on the "intuitive statistician" has prompted a new set of insights and debates concerning how and why the visual system might benefit from a compact representation of the optic array and how this might relate to crowding, sparse representation, efficiency coding, and processing limits. New research tools and imaging techniques coupled with solid psychophysical work have added substantially to the large base of work done in the 20th century. The present brief review acts as a summary of the ensemble of work prior to Ariely's (2001) landmark paper to encourage a comprehensive continuity of knowledge and reintroduce some of the contemporaneous concerns to help inform ongoing research and modeling.