Artists like Franz Liszt and Wassily Kandinsky probably had it, many scientists possess it as well: an additional channel of perception. The ability to see sounds as colors, taste words or feel letters is called synesthesia. The term comes from ancient Greek: “syn” means “together”, “aisthesis” means sensation – a fitting description for the phenomenon that when one sensory organ is stimulated, at least one other is also stimulated.
Synesthesia is not a disease and not an imagination or hallucination. Rather, it is a neurological-psychological phenomenon that occurs more frequently than previously thought. Recent researches assume up to 4% synesthetes in the population. In the past synesthetes were at best smiled at as somewhat cranky, in recent years the phenomenon has become better known and is rather perceived as an additional talent. Synesthesia also offers an exciting field of research for psychologists and neuroscientists, especially as they hope to use it to learn more about how human perception works in the first place.
Typical signs of synesthesia
Synesthetic sensations cannot be influenced: they arise involuntarily as a result of a specific trigger – often simple geometric shapes, but also abstract concepts such as days of the week or numbers, sounds and even feelings. Each synesthesia is unique: a certain stimulus triggers a certain additional sensation in a synesthete, which is reserved exactly for this stimulus. For example, if he perceives an A as blue, the blue tone of an H is different. Also, the experiences are not reversible: if the sound of a trumpet triggers the color sensation “red” in a person, he does not hear a trumpet when he looks at this red hue. Synesthetes perceive their perceptions as natural, remember them also later exactly and can describe them precisely.
Color hearing (audition colorée), i.e. color associations when hearing sounds, is the most common form of synesthesia. These sensations are also called photisms (phos = light); auditory sensations triggered by non-acoustic sensory stimuli are accordingly called phonisms (phone = voice). Even blind synesthetes can have sight-like experiences at the sound of certain noises, music, or voices – for example, as early as 1710, a person was reported to describe sound-related color experiences despite his blindness.
