By | June 10, 2022

Synaesthesia is a symptom that is still largely unknown to the general public, a peculiarity in the perception of sensory stimuli. Those affected always experience sensory impressions as a coupling of two or more perceptions.

What is synesthesia?

Synaesthesia was already described in scientific literature 300 years ago and today we know of famous sufferers such as Franz Liszt and Richard Feynman.

Synaesthesia only came into scientific focus in 1880 with the investigation of visualized numbers, and it has only been scientifically researched seriously since 1996. For what is pa, please visit

Those affected experience one or more sensory perceptions coupled and as an indissoluble unit. Synesthesia comes in many varieties, with the most common forms being photism, the perception of hearing with colors, geometric shapes, or color patterns, and colored hearing, the perception of sensory information with colors. Synesthesia varies from person to person.

There are various statements about the frequency of the phenomenon, scientists assume that between 1 in 200 and 1 in 2000 people could be a synaesthete. The number of unreported cases could be much higher, because those affected experience their perception as normal and are not aware of their synaesthesia.


Most synesthesias are based on hereditary causes, which could be proven by two facts: those affected describe their special perception as never having been different and synesthesias occur more frequently in families, around 25% of first-degree relatives can be diagnosed as affected.

Those affected have deviating nerve connections, so that one sensory stimulus causes two or more scientifically measurable sensations. Due to these nerve connections, synaesthesia could be determined as a scientific fact and anatomical peculiarity, so the sensory impressions are medically real.

Synesthetic perceptions are better remembered than the triggering stimulus, so those affected can remember the color better than the triggering sound. In addition, synesthetic experiences are involuntary and unconscious and cannot be consciously controlled or stopped by those affected. However, synaesthesia can also occur as a misperception in hallucinations, triggered by mental illness, epileptic seizures or after taking hallucinogens.

The causes of synaesthesia can be differentiated by their occurrence: while congenital synaesthetes describe the sensory impressions with full consciousness in everyday life, in the case of hallucinations all perception is disturbed.

Symptoms, Ailments & Signs

Synesthesia is often not recognized as a special feature by those affected for a long time, since it is innate and a synaesthete has always perceived sensory stimuli from his environment in this way. In those affected, different areas of perception are linked. As a result, they experience two or more different types of perception simultaneously in response to a single sensory stimulus.

Hearing colors is considered the most common type of synesthesia: For those affected, each tone has its own color that he perceives when hearing it. However, there are many different types of synesthesia. It can affect all of the senses, hearing, seeing, tasting, smelling and touching. In addition, every synaesthesia is unique. The location of perception is difficult to pinpoint and may be inside or outside the synesthete’s body.

The coupling of the sensory perceptions happens involuntarily and cannot be suppressed. As a rule, synaesthesia is irreversible: if a synaesthete perceives a number in a specific color, this color does not necessarily have to cause the number to be seen.

Some synaesthetes can achieve above-average memory performance, since synesthetic perceptions are particularly easy to remember. Another symptom that can occur is hypersensitivity, in which intense experience leads to rapid sensory overload. Synaesthetes can also have a particularly well-developed creativity.

Diagnosis & History

As described, congenital synesthesia can be detected by brain scans. The most important methods for displaying the cross-connections in the brain are functional magnetic resonance imaging ( MRI ) or positron emission tomography ( PET ).

The simpler diagnostic method is an association test. Test subjects are played tones of different pitches, to which they are asked to assign one of several color charts. While those who are not affected associate light tones with light colors in this test, synaesthetes have their own laws of assignment that deviate from this rule, but can explain the choice of assignment in a logical and understandable way for them.

Synaesthesia is congenital and usually shows a progressive course; many synesthetes report an increase in sensory impressions with advancing age.

In contrast to congenital synesthesia, hallucinogenic is undetectable. The only thing that can be determined is the possibility of occurrence based on the substances taken or the existing diseases.


Because of the many forms of synesthesia, it is not necessary to speak of complications in general. There are also no complications as a result of treatments, since synaesthesia has no clinical significance and therefore no therapy is required. Synaesthetes are most likely to experience complications in the form that the additional sensation that occurs with a primary stimulus can be unpleasant, which can result in avoidance of certain stimuli.

For example, hearing a certain tone can lead to a sensory – in this case unpleasant or annoying – sensation. However, these unwanted sensations vary greatly in different cases of synesthesia and often do not occur.

Complications can also arise from conditions that led to synesthesia in the first place. Few possible causes are known here, but strokes and severe craniocerebral trauma should be mentioned. Overall, it can be said that synaesthesia is a phenomenon that is usually perceived as pleasant.

Since most synaesthetes do not know their perception differently, there are no problems. Rather, this different form of perception often leads to outstanding achievements. Only when “learning” to perceive and the mixing of several sensory levels can the synesthete encounter certain problems through ridicule or rejection.

When should you go to the doctor?

In the case of synesthesia, the affected person is dependent on medical treatment and examination in any case. This disease cannot heal itself, so an examination by a doctor must be carried out in any case. The earlier the disease is detected, the better the further course. If no treatment is given, the symptoms will worsen. A doctor should be consulted for synaesthesia when the person affected can no longer properly perceive external stimuli and feelings.

This leads to hearing or vision problems, which can significantly restrict everyday life. Serious symptoms can also occur when tasting or smelling, and a doctor should be consulted. As a rule, a general practitioner can be consulted for synesthesia. Further treatment is then carried out by a specialist. As a rule, this disease does not reduce the life expectancy of those affected.

Treatment & Therapy

Hallucinogenic synesthesia is usually treated by treating the underlying disease or by stopping the use of hallucinogens. This is also for prevention.

Congenital synesthesia is not actually a disease. On the contrary, many consciously affected people see their specialness as an ability and gift. Accordingly, no treatment of the anatomical peculiarity is required and there is no possibility of prevention.

Medical research is now trying to use synesthesia as a therapy for pain patients. A team of researchers found in experiments with mice that the genes for synaesthesia and pain perception are identical. In the mice, pain stimuli did not reach the cerebral cortex, which is responsible for the awareness of pain, but rather the brain regions responsible for sensory impressions and perceptions. The synesthetic mice apparently did not feel the pain, they perceived it as an impression of smell or taste.

The aim now is to understand these research results in order to be able to use them to develop new pain medications.


In most cases, sufferers of synesthesia have only limited measures or options for aftercare available, as it is a rare disease. If the disease has been present since birth, it can usually not be completely cured. Therefore, those affected should consider genetic testing and counseling if they wish to have children in order to prevent the disease from recurring.

As a rule, it cannot heal on its own. Most patients with synaesthesia are dependent on a surgical procedure, which can relieve the symptoms permanently. Strict bed rest should be maintained after such a procedure, also avoiding exertion or physical and stressful activities.

Many of those affected are dependent on the help and support of their own families due to synaesthesia. Psychological support can also prevent the development of depression and other psychological problems. Contact with other people affected by the disease can also be useful, as information can be exchanged. The disease also reduces the life expectancy of those affected in some cases.

You can do that yourself

People who have been diagnosed with synesthesia are highly sensitive to sounds, colors and other stimuli. You get exhausted faster and need time to process the impressions. It is the duty of the relatives to treat the affected person with understanding.

If the child is diagnosed with synesthesia, it is advisable to contact other affected parents. Through the experience of parents whose child has a synesthetic disposition, raising their own child is less stressful. In order to promote the phenomenon as well as possible, suitable special needs kindergartens or schools must be organised. Although children with synaesthesia can take part in normal everyday life, there are often other psychological abnormalities. Therefore, when synaesthesia is diagnosed, you should always work together with specialists and trained special education teachers.

With mild synesthesia, the child often has no limitations at all. However, because affected children usually think and act differently than people without synaesthesia, patience is always required when dealing with those affected. Good communication at home helps children with synesthesia to process their unique world of thoughts and to talk about them with people they trust.