Synesthesia: Beyond Just Proof

Veronica Gross
Vision & Cognition Laboratory
Department of Psychology
Boston University 

Synesthesia is a unique phenomenon in which a stimulus presented 
to a single sense generates not only the primary experience, but 
also a secondary percept in another or a related sense. Until 
recently, the bulk of synesthesia research has been focused on 
proving the existence of synesthesia as a valid neurological 
phenomenon and attempting to determine its cause. Our research 
instead focuses on the potential cognitive and behavioral effects 
of synesthesia, particularly in the realm of short-term memory 
and visual pop-out. Numerous self-reports from synesthetes 
(people with synesthesia) imply that they experience better 
memory than non-synesthetes for some stimuli, such as faces and 
factual information, while several smaller studies have striking 
demonstrations of visual pop-out. We have chosen to explore these 
potential differences in color-graphemic synesthetes, those who 
see a color when they read an uncolored letter, word, and number. 
Our exams separate stimuli into items that strongly, weakly, or 
do not trigger their synesthesia in an attempt to clarify these 
self-reports. In addition, we have piloted a novel pop-out 
paradigm that measures performance speed and accuracy in a simple
letter identification and location task. These tests represent 
the first systematic investigation of these cognitive/behavioral 
phenomena and the first step in creating a more thorough 
synesthete neuropsychological profile.