What is Synesthesia & Chromesthesia?
Seeing music as colors. Taste salt and see colors. Synesthesia is the ability to perceive through your senses information you receive intellectually.
Criteria for Synesthesia 
"The colours my daughter 'sees' for each musical note."
Image by Jess, Photo by Andrew Bullock, 2009 
What is Synesthesia?
"Synesthesia is a condition in which one sense (for example, hearing) is simultaneously perceived as if by one or more additional senses such as sight. Another form of synesthesia joins objects such as letters, shapes, numbers or people's names with a sensory perception such as smell, color or flavor. The word synesthesia comes from two Greek words, syn (together) and aisthesis (perception). Therefore, synesthesia literally means 'joined perception.' "
History and Research
A Statistical Study of Pseudo-Chromesthesia
and of Mental-Forms
Mary Whiton Calkins
The American Journal of Psychology
Vol. 5, No. 4 (Jul., 1893), pp. 439-464
Published by: University of Illinois Press
Stable URL: http://www.jstor.org/stable/1411912
Page Count: 28