On the Perceptual Reality of Synesthetic Color

2 Synesthesia – the mental mixture of real and illusory sensory experiences – is incredibly fascinating to read or hear about but frustratingly complex to study. Those of us who are not synesthetes are spellbound by the accounts of those who are, but at the same time we are mystified by why these mixtures would occur. As the chapters in this volume document, scientific investigation of synesthesia has rapidly developed into an area of great interest and debate within cognitive neuroscience, and our group at Vanderbilt is among those seeking to understand this fascinating phenomenon. In our work, we have focused on color-graphemic synesthesia: the perception of color when viewing achromatic alphanumeric characters (in this chapter, we use the term " achromatic " to refer to figures printed in black ink against a white background). Judging from the existing literature on synesthesia, as well as from the tremendous volume of unsolicited, anecdotal accounts we have received from synesthetes, color-graphemic synesthesia appears to be the most common form of the condition. Certainly this variety of synesthesia provides for some of the most memorable and amusing accounts. Thus, for example, one individual who sees digits vividly colored volunteered to us that she performed arithmetic using her colors and was surprised upon first learning that others did not: " I thought everyone did math with colors – that yellow plus yellow was red for everyone. " Another individual complained that she often confused appointments scheduled for Tuesday or for Thursday, because both days are " red. " Still another confessed to an unfounded dislike of the city of Houston " just because the word was a ugly shade of brown " and another acknowledged that " my husband knows that I couldn't have married him if his name had been the 'wrong' color for me … we are, color-wise, perfectly compatible. " These and the many other transcriptions we have compiled from synesthetic volunteers lead us to accept that their graphemic colors are vivid and, in some sense, real. 3 The great challenge in learning about synesthesia, of course, is to develop objective experimental strategies for going beyond these colorful verbal accounts. To be honest, our interest in synesthesia grew entirely out of the fortuitous identification of a few individuals within our academic community who experience color-graphemic synesthesia. While none in our research group was expert in color vision, we were all intrigued …