The Hidden Sense. Synesthesia in Art and Science

by Cretien van Campen
The MIT Press, Cambridge, MA, 2007
208 pp., illus. 44 b/w. Trade, $29.95/£19.95
ISBN: 0-262-22081-4.

Reviewed by Jan Baetens

Cretien van Campens’s study on synesthesia, the sensory experience that makes us perceive words in colours and/or colours in words, for instance, and, more generally, that is the phenomenon that makes us activate two or more senses when semiotically speaking only one sense is addressed, offers a clear and refreshing view of a phenomenon that has been long-time taken for an hallucination or a delusion. Strongly relying on the latest scientific experiments (brains scans) as well as on a lifelong personal research on and with synesthetes (persons being able of synesthetic perception), the author manages to offer a discussion of synesthesia that is of interest for the specialists as well as for the broader public.

The book is divided in three sections. In the first part, van Campen examines the synesthetic perception itself: What does one perceive when one perceives synesthetically? In the second part, he analyzes the way synesthetes think: How can synesthesia be framed as an occurrence of visual thinking? In the third part, he brings together the current scientific reflection on the phenomenon (both the thinking of those for whom synesthesia is an abnormal brain function and those for whom it is a normal brain function).

The author’s way of arguing finds always a good balance between direct experience (the testimonies of the many synesthetes with whom he has been working for many years now) and the scientific results of cognitive and neuroscientific research (of which he is able of giving very clear and readable reports and syntheses). The basic ideas defended in the books are quite simple. On the one hand, the author clearly defends the universality of synesthesia, not in the sense that we are all synesthetes without being aware of our synesthesia, but because synesthesia is part of human experience (we are all born synesthetes, and then our cultural and biological evolution separates our sensory experiences) and because, more importantly, synesthesia should be considered a specific form of what we are all capable of performing, namely "synchronestesia" (i.e. the simultaneous perception of various signs that address each a separate sense). Van Campen makes, therefore, a plea for making room for a "hidden sense", which is our ability to process information in a unified and more holistic way that lays behind or beyond the processing of information through separate senses. On the other hand, the author is also reluctant to reduce the universality of syn(chron)esthesia to a uniform and homogeneous phenomenon. He demonstrates very convincingly that synesthesia remains an essentially individual process (the many experiments with synesthetes prove that there is never an identity between the perceptions of two persons, at least not when the researcher tries to identify the sensory perceptions in a very fine-tuned manner) and that there is definitely a cultural bias in the perception of synesthesia (in Western culture, where taste and smell are not differentiated, synesthetic experiences will not take the simultaneous perception of taste as smell and of smell as taste into account, whereas in other cultures this will be seen as a clear example of synesthesia). Corollarily, van Campen refuses also to abandon his first-hand experiments and discussions with synesthetes and the many examples provided by art and history in order to make them match the findings of the results of modern brain scanning techniques. He remains critical of the findings of that kind of brain research, making always room for the individual testimonies and examples he presents and analyzes with great astuteness.

A less convincing dimension in this book, however, are the references to the art world. Obviously, synesthesia is a key dimension of many artistic expressions and movements, yet van Campen does always not pay enough attention to the possible tension between the status of the work and that of the author: The fact that a work features synesthesia does not imply at all that its author is himself or herself a synesthete; it is on the contrary perfectly imaginable that one has only a hearsay knowledge of synesthesia, but performs it artistically for reasons that have nothing to do with a sensory basis, but with an artistic agenda. It is clear that this was the case for the experimental Dutch poets of the 1950s, who used synesthesia not because they were synesthetes, but because synesthesia was part of their innovative rhetorical agenda. More generally, it would have been interesting if the author had asked questions on the cultural (un)willingness to tackle and foreground (or censor) synesthesia. The relationships with cross-cultural aesthetic tendencies such as the "ut pictura poesis" might have been useful here. Questions like these are unfortunately never asked, and for this reason this book is missing an essential feature, namely history. The Hidden Sense is a good and warm introduction to synesthesia and an important plea for its ‘normalization’. Yet for the reader who is looking for a cultural history of the phenomenon, the book will remain disappointing.