Metamers of the ventral stream revisited

Abstract

Peripheral vision has been characterised as a lossy representation: information present in the periphery is discarded to a greater degree than in the fovea. What information is lost and what is retained? Freeman and Simoncelli (2011) recently revived the concept of metamers (physically different stimuli that look the same) as a way to test this question. Metamerism is a useful criterion, but several details must be refined. First, their paper assessed metamerism using a task with a significant working memory component (ABX). We use a purely spatial discrimination task to probe perceptual encoding. Second, a strong test of any hypothesised representation is to what extent it is metameric for a real scene. Several subsequent studies have misunderstood this to be the result of the paper. Freeman and Simoncelli instead only compared synthetic stimuli to each other. Pairs of stimuli were synthesised from natural images …