Increasing Human Capacity: The Strange World of Synesthesia


The music lives in colour, it seems obvious to you. The velvet you caress with your hand tastes like chocolate. You count by following the rainbow of numbers in your mind, just as the letters of the alphabet have never been written simply in black on a white background. You feel that the world is not limited to the dimensions of your thought and that you can almost grasp in one perfect sensation all its immensity. You are probably a synesthete.

Nothing in intelligence that hasn't passed through our senses. »


Aylesthesia is the automatic, involuntary and permanent ability to associate senses of different natures. But it is also considered to be a neurological disorder that affects approximately one person in 2,000. A very feminine disorder: seven out of ten synesthetes are thought to be female. For many, it is like a gift: people with two or more linked senses. For example, reading this text in black and white triggers an odour or colours, with each word having a colour.

The term of Greek origin "aisthesis" refers to sensitivity, the ability to feel. Synesthesia is the ability to spontaneously and involuntarily associate senses of different kinds, such as "seeing music", "tasting the roughness of a surface" or "seeing coloured numbers".

All the senses can potentially combine but some associations are more frequent, others have never been described. It is specified on the Wikipedia site:

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- Synesthesia is involuntary and automatic.

- Synthetic images appear spatially, which means that they often have a defined position in space.

- synesthetic perceptions are consistent and generic

- synesthesia is memorable

- Synesthetic perceptions are emotionally charged...

- Synesthesia is not linguistic, and somehow ineffable...

- Synesthesia concerns people with brains that show no signs of disease.

The prefix "syn"The word "synthesis", which comes from the ancient Greek, expresses the idea of the whole, of a meeting, as in the words "synthesis", "synonym" or "synchronization" for example. Placed before the term "theory", it forms the neologism synestheory, whose ambition is to define a new movement of thought, another way of understanding the world. By retaining two letters from the word synesthesia, it reminds us that its inspiration comes from certain singular properties associated perceptions, which offer privileged and perhaps objective access to reality.

The synesthetical project postulates that thought and self-awareness, by nature limited in their capacities and singular to each person who claims them, do not allow for the consideration of all the information necessary for an impartial, objective and holistic study of the world. The general hypothesis of the project is that the experience of synesthesia can go beyond these constraints and be used as a tool for the analysis of existential questionings still without unequivocal answers, helping to a global, deconflictualized and as simple as possible understanding of all the problems posed by existence.

Excerpt from a program broadcast on Arte that deals with the senses. Here, a very interesting passage concerning the phenomenon of Synesthesia, or when multiple senses are stimulated at the same time in the perception of a phenomenon :

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To date, there is no unified descriptive and explanatory theory of reality that is recognized as valid for any situation, at any time, in any place, for any object or individual. Inspired by a special synesthesia experience which witnessed the matrix relationship of all the real objects interacting with each one of us, the syntheoretical model - an "Essay on the reason for everything " - claims to fill that gap. Sensory experiences offering privileged access to the universal substratum of knowledge and leading to verifiable productions will be called "sensory experiences". heuresthésies.


The synestheory project and its model are distinguished from other attempts to understand the world by the possibility of to experimentIn order to assess the relevance of each of their arguments, simply but with the utmost epistemological rigour. The alleged universality of the "Essay on the reason for everything" will have to submit to the experiment to prove its validity.


Based on the results of the study protocols set up and within the framework of the proposed model, the practical implementations are conceivable. The field of possibilities is vast and still little exploited, but these applications will aim, through hardware and/or software devices, to improve and increase the perceptive capacities of human beings in their relation to their natural and technological environment, particularly in the field of disability.

These potential applications are currently confidential but their main objective will be to make the adaptive benefits and emotional contributions of multimodal sensory experiences accessible to everyone.

Through theory, experimentation and application, the synestheory project hopes to achieve the reconciliation of humanity with itself and its environment, trying to find, in the elementary processes of perception and cognition, the intimate link of each of us with the unique matrix of the physical and metaphysical universe. (Source : Vincent Mignerot)

"It is said that everyone experiences a perfect moment, from time to time, an experience of complete peace and connection with the world, (...) Suddenly I had the experience of forgetting myself and, for a brief and brilliant moment, I had the impression that all my anxiety and uneasiness disappeared. (...) I imagine these moments as fragments or splinters scattered over a lifetime. If someone could glue them together, they would make a perfect hour, or even a perfect day. And I think that this hour or day would bring him closer to the mystery of being human. It would be like a glimpse of heaven. Daniel TammetI was born on a blue day /Book conclusion. Edition les Arènes 2007) ".(nterview of Daniel Tammet in the show "Salut les terriens" of March 7, 2009)

Synesthesia Disorder: History

Synesthesia disorder has apparently been known for quite some time. It was "rediscovered" in 1976 by Richard CYTOWIC. But let's quote some authors who have mentioned it: the first is the ophthalmologist Thomas WOOLHOUSEIn 1710, the case of a blind man who perceives sounds that induce coloured visions was described.

Sir Francis GALTON also mentioned in 1907, in his book "Inquiry into Human Faculty an dits development", the existence of such phenomena in some people. He indicates the heredity of this tendency. Alexandre LURIAthe great Russian neurologist, studied a case (" A prodigious memory."). There are few researchers in the world. Any difficulty finding people to test? Or anything else?

baroncohenA remark by Richard CYTOWIC; that was in 1979. He had met his first synesthete. Nobody was interested in his case. A colleague even told him, "Stay out of this. It's too "new age". He persisted, and specialized in the phenomenon. Other researchers, such as Simon BARON-COHEN of Cambridge University, are taking an interest and the community is growing. There are just about 30 scientific researchers on the subject. (Source :

The different forms of synesthesia

Synesthesia associates the senses and/or concepts with sensations, in an irrepressible and blatant way, unlike non-synesthetes who may experience it, but in a very diminished way. Although not all possible sense associations could be described, it is likely that all of them exist.

For most of us, we possess the five senses that everyone knows: sight, smell, touch, hearing and taste. The scientific community holds another sense that is the proprioception. The latter concerns the mechanisms of perception of the environment such as balance or sensations of movement, but also pressure or temperature.

According to the associations observed, several types of synesthesia could be described, grouped under three main categories:

Bimodal Synesthesia

As its name suggests, it is a cross between two senses, such as taste and touch: caressing the bark of a tree, for example, causes the sensation of a salty taste in the mouth.

Unidirectional synesthesias are the most common: a stimulus affecting one sensory modality causes synesthetic perceptions to appear in another modality, without the reverse occurring. For example, a sound will produce an odorous sensation, without an odour causing a sound sensation in the same person.

In the case where the senses are doubly associated, which is relatively rare, it is called bi-directional synesthesia.

- Multimodal Synesthesia

When three or more senses come together, we speak of multimodal synesthesia: a sound, for example, causes both a sensation of taste and light, as in the case of a synesthete who felt an acidic taste and a flash of light before his eyes when he heard a sudden and intense sound. Multimodal synesthesias are rare unless they are categorical synesthesias.

Categorical, or cognitive, or conceptual synthetics

These terms refer to more subtle associations of secondary sensations, more elaborate from a cognitive point of view (shapes, colours, positions in a "virtual" space...), to cultural categories (number, letters, symbols, words, time, month or date, quantity...). The best known examples are those of grapheme-colour synesthesia (also called coloured alphabet) and numerical synesthesia, as well as several forms of cognitive synesthesia involving sounds or music.

synesthesiemusicThese synesthesias are very particular and their manifestations can take many forms, which are generally grouped under one name, according to the associated meaning and not categories. Coloured hearing is an example: in some synesthetes such as Olivier MessiaenAs a composer, the chords gave a feeling of colour. The synesthetes music → colors perceive colors in response to sounds. Like synesthetes grapheme → colors, synesthetes rarely report the same colors for given tones (for one synesthete, an A-sharp may be red; for another synesthete, it will be green).

For Amy Beach, another American composer and pianist, it is the tonalities that give rise to colourful sensations. Duke EllingtonAs for him, he perceived his synesthetic colours according to the timbre of the instruments. We could cite other great synesthetic musicians such as Hélène Grimaud...pianist; György Ligeti...composer; Franz Liszt ; Nikolai Rimsky-Korsakov ; Jean Sibelius ; Michael Torke ; Alexander Scriabin. Closer to us, Richard Dubugnon who confides that his (...) "own pieces, I'd say they're pretty green, green-yellow. It's a whole, I don't dissociate the notes from the orchestration. It's really in the harmonic reverberations. »

kandinskyPainters, like Kandinsky or David Hockney. Writers, like Baudelaire: "Scents, colours and sounds answer each other in a deep, dark unity" like Vladimir Nabokov or Rimbaud. "who threw sonnets on paper in vowel colours" (1) : "An overcast morning in July. A taste of ashes flies in the air, - a smell of wood sweating in the hearth, - the rusty flowers, - the sacking of the walks, - the drizzle of the canals by the fields, - why not already the toys and incense? » (Illuminations, Sentences). For Rimbaud, does a sound resonate close to him, it returns a colour of the same sensitive value in return? (ibid.)

This complexity is related to the multidimensionality of the senses and stimuli themselves: a pure sound has a timbre, an attack, an intensity etc... and different brain regions react separately to these dimensions, which are then considered as the senses.s" secondary. For other synesthetes, melody and rhythm are involved. In the same way, several types of categorical synesthesia are grouped under the term grapheme-colour synesthesia: see the colours of letters or words. For some grapheme-colour synaesthesia, dimensions such as calligraphy or lower/upper case, do not intervene and do not change the colour of the letter. (Source: Carnegie / What is synesthesia?

All these specificities make the definition of categorical synesthesias very complex.

All human beings would be synesthetic

synesthesiecerveauInitially, the lack of understanding of synesthesia was due in part to the associations described by synesthetes, which were very precise and detailed, prompting some experts at the time to associate the condition with mental disorders such as schizophrenia. Even more recently, it has been suggested that synaesthesia is a step back to a more primitive state.

Today, scientists have tools that allow them to probe the brain, something that was impossible to do 200 or even 10 years ago. One such tool is a type of brain scanner called Diffusion MRI, or Diffusion Tensor Imaging, which allows scientists to see the connections between different areas of the brain. Opposite: one Diffusion MRI of the brain presenting the nerve fiber bundles.

"We can see that there are many connections between the associated senses in synesthetes," the psychologist said. David Brang. Visualizing these connections between sensory brain regions may help explain why some forms of synesthesia exist and why the condition tends to be unidirectional; for example, numbers may evoke colours, but colours do not generally evoke numbers. These studies could also help test an idea proposed by some scientists that: all human beings possess the neural mechanism for synesthesia, but that it has been suppressed or extinguished for some unknown reason.

Another positive development in synesthesia research is that scientists are relearning to listen to their subjects, according to the authors of the study. They are beginning to believe them. Studies indicate that synesthesia today is about seven times more common among artists, poets and novelists than in the rest of the population, and some scientists have hypothesized that synesthetes are better at connecting independent ideas.

"We worked with a novelist who swore that her synesthesia helped her find metaphors," said Brang. "She knows what color a word should be before she even knows what the word is. "Some scholars, with synesthesia, were known to perform amazing feats of memorization, such as memorizing the value of pi to 22,514 digits. Other synaesthetes are able to tell the difference between very similar colours or have a keen sense of touch.

A recent article from Futura Sciences that just came out talks about chimpanzee synesthesia that would unlock one of the secrets of language. Like humans, chimpanzees associate colors with certain sounds. This is a clue to understanding the origin of language, explains the famous paleoanthropologist Pascal Picq.

Despite recent progress, many questions about synaesthesia remain, such as whether animals have the same mental experiences or how different brain chemicals affect the state and exact role of genetics in determining the cognitive and creative abilities of the synaesthete.

Furthermore, David Brang adds, "If this trait is so cool and important, why don't we have it, or rather, why don't we have it anymore? ».

(Source: study published on PlosOne: Survival of the Synesthesia Gene: Why Do People Hear Colors and Taste Words?)

Synesthesia News

synesthesieespace– Espace Synesthésie, Paris - 15 rue Denfert-Rochereau 93200 Saint-Denis - +33 (0)1 40 10 80 78 /

Virtual Art Center " Synesthesia " which opened in 1995 a space on the web dedicated to the theories and practices of contemporary art, in the context of new technologies. Synesthesia's Virtual Art Centre presents works specially designed for the Internet.

– New video game "Nexus" in which the designers of the game want to create a mixture of senses and a correspondence between sounds, colours and shapes.

- Read: Ludwig Wittgenstein and Vincent Mignerot, towards a philosophical legitimization of the synesthetic project.

- Read " Wednesay is in indigo blue" by R. Cytowic and D. Eagleman. (this book won the 2011 Montaigne Medal award).

- Read " Musicophilia, the music, the brain and us " of Dr. Oliver Sachs.

- Listen to Jean-Claude Ameisen talk about synesthesia on France InterThe Beats of Time", its history and its implication in the perception of everyone...

Video presentation of the synesthesia projectFull version (1h20)

Short films illustrating auditory synesthesia

- Read " Colors and images in midmapping

To go further: 

- Synesthesia with humor | Project Synesthesia in Synesthesia, Science, Art and Literature (Epistemocritical review)

- Synesthesia with humor | Synesthesia Project in Cartoon of Synesthesia (Synesthesia)

- Vincent Mignerot in Admire the singing of the whales!

- Vincent Mignerot in The less you hear, the more sensitive you are to touch...

- Claire Petitmengin: The intuitive experience

- Book by Vincent Mignerot "Essay on the reason for everything"

- Association Plasticities, Sciences, Arts

- Newsletter Synesthesia (Contemporary art)


This article was originally published on January 14, 2016.



(1) Rimbaud, Stefan Zweig - 1st edition in French April 2015 

Illustration: Table "Mac Donald's Synchrony" - Wright - 1914


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