Synesthesia: Inherited or Learned?

Women are more likely to be affected by synesthesia than men – estimates vary from only a slight increase to a 7-fold incidence. Affected individuals report that they have “always” lived with the coupling of their senses “as far back as they can remember.” Meanwhile there are indications that newborns in principle have such an ability, but in most people these additional synapses atrophy after a few months. Why this does not happen in synesthetes is still unclear. However, since it occurs frequently in families, it could well be genetically determined and thus hereditary. It is interesting that certain characteristics occur more often in synesthetes than in others. These include giftedness and creativity, but also sensitivity to sound and attention disorders. Perhaps this can be thought of as positive and negative consequences of increased stimulus perception; the exact relationships have not yet been clarified.

Synesthesia cannot be learned

Even people without synesthesia sometimes have memory experiences in which some senses partially interact. Thus, when listening to a certain music, one feels exactly the desire one had 20 years earlier when dancing to this song with the beloved, or smells the apple pie of the grandmother who used to hum to exactly this hit song while baking. But such conscious sensory associations have nothing to do with typical, innate color vision. In non-synesthetes, sensory stimuli are assigned to certain situations and thus stored in the brain. Thus, when remembering, they emerge from the memory together. Real synesthesia, however, occurs involuntarily, spontaneously and without the affected person being able to foresee it or filter it out of his consciousness.

Medical technology shows what is going on

Synesthesia has nothing to do with hallucinations; it occurs with unclouded consciousness. Modern medicine has been able to prove that color vision, for example, is not the imagination of those affected. The EEG and especially functional

magnetic resonance imaging can show the activity of individual brain areas in real time. In this way, scientists have been able to show that in synesthetes, a single sensory stimulus – in most cases a sound – activates not only the auditory center, but also the visual center at the same time. Thus, the color experiences are “real” even if the affected person is the only one who can see them.