Synesthesia comes from the Greek "syn" (meaning union) and "aisthesis" (sensation), literally interpreted as a joining of the senses. Synesthesia is an involuntary joining in which the real information from one sense is joined or accompanies a perception in another. Dr. Cytowic reports extensive research into the physical, psychological, neural, and familial background of a group of synesthets. His findings form the first complete picture of the brain mechanisms that underlie this remarkable perceptual experience. His research demonstrates that this rare condition is brain-based and perceptual and not mind-based, as is the case with memory or imagery. "Synesthesia" offers a unique and detailed study of a condition which has confounded scientists for more than 200 years.

The ten people in one million who are synaesthetes are born into a world where one sensation (e.g. sound) conjures up one or more others (e.g. taste or colour). Although scientists have known about synaesthesia for two hundred years, until recently the condition has remained a mystery. Extensive experiments with more than forty synaesthetes led Richard Cytowic to an explanation of synaesthesia that emphasized the primacy of emotion over reason. In this medical detective adventure, he offers a new view of what it means to be human that turns upside down conventional ideas about reason, emotion, and who we are. This new edition contains a Foreword by Jonathan Cole and an Afterword from the author.

In this medical detective adventure, Cytowic shows how synesthesia, or "joined sensation," illuminates a wide swath of mental life and leads to a new view of what it means to be human. Richard Cytowic's dinner host apologized, "There aren't enough points on the chicken!" He felt flavor also as a physical shape in his hands, and the chicken had come out "too round." This offbeat comment in 1980 launched Cytowic's exploration into the oddity called synesthesia. He is one of the few world authorities on the subject. Sharing a root with anesthesia ("no sensation"), synesthesia means "joined sensation," whereby a voice, for example, is not only heard but also seen, felt, or tasted. The trait is involuntary, hereditary, and fairly common. It stayed a scientific mystery for two centuries until Cytowic's original experiments led to a neurological explanation-and to a new concept of brain organization that accentuates emotion over reason. That chicken dinner two decades ago led Cytowic to explore a deeper reality that, he argues, exists in everyone but is often just below the surface of awareness (which is why finding meaning in our lives can be elusive). In this medical detective adventure, Cytowic shows how synesthesia, far from being a mere curiosity, illuminates a wide swath of mental life and leads to a new view of what is means to be human-a view that turns upside down conventional ideas about reason, emotional knowledge, and self-understanding. This 2003 edition features a new afterword.

An accessible, concise primer on the neurological trait of synesthesia-vividly felt sensory couplings-by a founder of the field. One in twenty-three people carry the genes for the synesthesia. Not a disorder but a neurological trait-like perfect pitch-synesthesia creates vividly felt cross-sensory couplings. A synesthete might hear a voice and at the same time see it as a color or shape, taste its distinctive flavor, or feel it as a physical touch. In this volume in the MIT Press Essential Knowledge series, Richard Cytowic, the expert who returned synesthesia to mainstream science after decades of oblivion, offers a concise, accessible primer on this fascinating human experience. Cytowic explains that synesthesia's most frequent manifestation is seeing days of the week as colored, followed by sensing letters, numerals, and punctuation marks in different hues even when printed in black. Other manifestations include tasting food in shapes, seeing music in moving colors, and mapping numbers and other sequences spatially. One synesthete declares, "Chocolate smells pink and sparkly"; another invents a dish (chicken, vanilla ice cream, and orange juice concentrate) that tastes intensely blue. Cytowic, who in the 1980s revived scientific interest in synesthesia, sees it now understood as a spectrum, an umbrella term that covers five clusters of outwardly felt couplings that can occur via several pathways. Yet synesthetic or not, each brain uniquely filters what it perceives. Cytowic reminds us that each individual's perspective on the world is thoroughly subjective.