What is Synesthesia?

The term synesthesia comes from the Greek: syn= together and aisthesis= sensation. Synesthesia is a special ability in which sensory impressions are mixed. This means that when one sensory organ is excited, sensations from another sensory organ appear in addition to those belonging to it: For example, music acquires shapes and structures that change with melody and timbre before the inner eye.

With all senses

Such connections are possible between all five sensory areas. However, the most common is “colored hearing.” Here, sounds, music or speech are experienced simultaneously with colors. Synesthesia occurs much more frequently in women than in men (by a ratio of 8:1) and much more often in some families than in others. Scientists suspect that synesthetes have a genetic alteration of the X chromosome. However, the concrete proof is still pending. The frequency in the population is about 1:1000.

There are many theories to explain how mixed sensory perceptions can occur. For example, that synesthesia is caused by a so-called “cross talk” between otherwise separated nerve pathways. This means that on the way from the sensory organs to the processing centers in the brain, the signals make contact with each other.

Types of synesthesia

Researchers distinguish between “genuine” synesthesias, which usually begin in early childhood and in which a sensory stimulus is tightly coupled to a particular perception of color or shape, and acquired synesthesias, which occur in neurological diseases or with drugs such as LSD or mescaline and usually do not last. A third form is emotional synesthesia: it is not necessarily triggered by a stimulus, the affected person can evoke it arbitrarily.

Finally, there is “associative pseudosynesthesia”: here, people have actively learned to associate letters with colors in childhood.