PT  - JOURNAL ARTICLE
AU  - Mark W. Schurgin
AU  - John T. Wixted
AU  - Timothy F. Brady
TI  - Psychophysical Scaling Reveals a Unified Theory of Visual Memory Strength
AID  - 10.1101/325472
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 325472
4099  - http://biorxiv.org/content/early/2019/08/16/325472.short
4100  - http://biorxiv.org/content/early/2019/08/16/325472.full
AB  - Almost all models of visual memory implicitly assume that mnemonic representations are linearly related to distance in stimulus space. Here, we show that neither memory nor perception are appropriately scaled in stimulus space; instead, they are based on a transformed similarity representation that is non-linearly related to stimulus space. This result calls into question a foundational assumption of virtually all extant models of visual working memory. Once psychophysical similarity is taken into account, aspects of memory that have been thought to demonstrate a fixed working memory capacity of ∼3-4 items and to require fundamentally different representations -- across different stimuli, tasks, and types of memory -- can be parsimoniously explained with a unitary signal detection framework. These results have significant implications for the study of visual memory and lead to a substantial reinterpretation of the relationship between perception, working memory and long-term memory.