Synesthesia: Characteristics, Types And Functioning

The synesthesia is a peculiar process of perceptual systems in which humans are treated together various types of feelings concerning different meanings in the same perceptive act.

In this way, the person manages to perceive as a whole two different perceptions such as sound and color. It seems strange that this can happen, but it is a phenomenon scientifically proven and experienced by various people in the world.

The sensory possibilities that can appear in a synesthetic person are multiple; can hear colors, see sounds, taste textures or associate different stimuli in the same perceptual sense.

In addition, the sensory associations are infinite, since rarely two synaesthetic people share the same characteristics in terms of their perceptual capacity.

Features of synesthesia

Activation of two or more senses before stimuli

When we speak of synesthesia, we refer to a process of human perception in which two or more senses are activated when perceiving stimuli.

“Normal” people, when we hear a sound, be it a musical note or any noise, in our brain the receptor senses related to the ear are activated.

However, what happens with synesthesia is that when listening to a sound, not only the senses related to the ear are activated, but other different sensory modalities can be activated, such as the visual one.

Thus, a synaesthetic person has the peculiarity that he is capable of activating more than one perceptual sense when faced with a specific stimulus.


The most frequent are usually those that involve a letter and a color, whole words and a color, and a number and a color.

However, there are also others that are somewhat more questioned but equally studied, such as the combination of pain and color.

Thus, we see that all synesthesia phenomena refer to the involvement of two perceptual modalities before the same sensory stimulus.

In this way, a person with synesthesia would have the ability to see sounds or hear images.


By involving different perceptual modalities in the same sensory sense, the experimentation of emotions and personifications also enters with great force.

This is especially important when we analyze synesthesia within the artistic world, giving a high creative capacity to this peculiar phenomenon.

How many people have synesthesia?

When we try to understand the phenomenon of synesthesia, it is difficult for us to assimilate that there are people who have sensory capacities so different from those of “normal” people.

Likewise, it is difficult for us to clearly imagine how it can be that a person can perceive stimuli through different sensory modalities or even through more than one perceptual sense simultaneously.

Rare phenomenon

The truth is that synesthesia has always been considered a very rare phenomenon, that is, there are very few people in the world who possess this type of capacity.

However, the great scientific interest that is uncovering this phenomenon, as well as the recent link between synesthesia and art or creative ability , has shown that the prevalence may be much higher than previously thought.


Thus, despite not having exhaustive results and data today, there are scientists who suggest that the prevalence of synesthesia could be up to 100 times higher than was initially believed.

In fact, researchers who point to a high prevalence of the phenomenon of synesthesia affirm that one in every 23 people could have this strange phenomenon.

Obviously, these data have not been fully corroborated or reliably demonstrated, so affirming such a high prevalence of synesthesia could be an act of excessive optimism.

Most common type

However, certain scientific data have been reported on the prevalence of synesthesia, which although they have to be analyzed with caution, would indicate that the most common type of synesthesia is the ability to see colors when they hear letters or numbers , a phenomenon that could be present in up to 1% of the population.

Despite all provisional data, it is clear that synesthesia is still today a confusing phenomenon, difficult to define and characterize, so it is not possible to clearly comment on how many people may have this type of characteristics.

Synesthesia music – color

The discovery of subjective synesthesia is given to Lussana, who in 1883 gave evidence of the existence of these phenomena. Likewise, this author dedicated himself to looking for the relationship between colors and emotions

In formulating his research, he hypothesized that if letters and emotions easily evoke a color, why can’t they also evoke a sound.

Physiology of colors

Thus, in her book « Physiology of colors » Lussana relates the following aspects:

Colors are characterized by an increasing number of vibrations (from red to violet), which cause different excitations in the sight, to which different sensations correspond, which are then in turn related to different and diverse ideas ”.

In this way, Lussana points out that there is a natural and physiological relationship between the harmonies of colors and that of sounds.

Likewise, he commented that the brain centers belonging to color and speech are contiguous and are formed in the same convolution, a fact that could explain the origin of synesthesia. Thus, through these formulations, the first medical explanation of synesthesia is reached, in which sounds and colors are associated.

However, contradictions in themselves arise from these theoretical bases. That is, if the brain mechanisms discussed above are true, are they found in the brains of all people or only in those who have synesthesia?

Obviously, if synaesthetic people are very rare worldwide, these brain characteristics should be classified as rare or abnormal.


Following this line of research, the famous psychiatrist Bleuer, who focused a large part of his professional career on the investigation of schizophrenia  and psychotic disorders, also became interested in synesthesia.

The Swiss psychiatrist, together with Lehman, published the most important research on synaesthetic phenomena.

Specifically, he studied a sample of 576 people, of whom 76 were “audio colorists”, that is, they had the peculiar ability to associate auditory and visual perceptions.

Through the study of these 76 people, we begin to search for a definition that can be optimally adapted to the peculiar characteristics of “colored hearing”, which ends up being the following.

«In certain individuals the hearing of a sound is immediately accompanied by a luminous and colored sensation that is repeated in an identical way while the auditory sensation is produced.

In this way, it is concluded that certain synaesthetic people are capable of mentally reproducing visual sensations through the capture of an auditory stimulus.

Synesthesia and art

Research on synesthesia during the 19th century has continued and increased in recent years.

Due to the particular characteristics of this phenomenon, which provides an infinite increase in the perceptual capacities of the human being, synesthesia has become a subject of special interest in the artistic field.

In fact, no current presents as much interest for the senses and expressive and perceptual capacity as art, so it is quite understandable that it is this discipline that has devoted the greatest research efforts to the study of synesthesia.

In this sense, during the last 20 years, studies that relate music to painting, music to sculpture and music to color have gained special importance.

Neuronal plasticity

Neuroimaging studies have shown how neural plasticity in human brains can provide a large number of mental abilities.

In fact, it has been shown how the mix of stimuli captured through 27 sensory mechanisms provides the particular “world” of human perceptions.

Regarding the relationship between music and painting, many authors look to synesthesia for their source of inspiration.

Likewise, artists who are not synesthetic, seek to exploit this ability, helping themselves with the mixture of sensory perceptions to develop their creativity.

In this way, we can currently find a large number of pictorial works in which the modality referring to painting is related to the musical one.

Especially in the Renaissance you can find works such as Titian, which is influenced by Giorgione, The Country Concert or Venus recreating herself with love and music , where a clear musical influence is displayed reflected in the pictorial paintings.

Music and color

Regarding the relationship between musical tonality and color, the main interest is in the ability to evoke colors through musical harmonies.

As we have mentioned, synaesthetic people are able to automatically associate a color with a musical note, always relating the same musical tonality to a specific color.

The main characteristic is that each synaesthetic person has particular association categories, that is, not all synesthetes associate the same color with the same musical tonality.

On the other hand, non-synesthetic people do not make this automatic association between musical tonality and color, so they can try to associate colors with harmonies in a more anarchic way and motivated by different variables.

Normally, dark colors are associated with low musical tones, and light colors with higher sounds.

In short, the phenomenon of synesthesia is very useful to realize that human beings are capable of influencing and being influenced, through art, by multiple sensory modalities.

As the Russian painter Kandiski affirms, “art is the language that speaks to the soul of things that are for it daily bread, which it can only receive in this way.”


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  2. Compeán, Javier (2011). Synesthetic tonality: Relations between the tonality of music and color through a personal proposal. (Doctoral thesis). Polytechnic university of Valencia. Guanajuato-Mexico.
  3. Córdoba, MªJosé De (2012). Synesthesia: Theoretical, Artistic and Scientific Foundations. Granada: Artecittà International Foundation.
  4. Hubbard, EM, Arman, AC, Ramachandran, VS & Boynton, GM (2005). Individual differences among grapheme-color synesthetes: brain-behavior correlations. Neuron, 45 (6), 975-85.
  5. RIERA, Nadia. (2011). Sound-color relationship in the synaesthetic experience of classical music. (Doctoral thesis). Central Western University “Lisandro Alvarado”. Barquisimeto, Venezuela.

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