Nepedia
Back to Discover
Advanced Reader
🧬

Synesthesia

life science Maturity 7-9 Next article →

Synesthesia is a unique perceptual phenomenon where the stimulation of one sensory or cognitive pathway triggers an involuntary experience in another. This means that a person's senses can cross over, creating connections that most people do not experience. While we usually think of the five traditional senses, synesthesia can also involve other perceptions like temperature, time, or internal bodily sensations. People who experience these overlapping sensations are called synesthetes. Because every person's brain is unique, the specific way they experience synesthesia varies based on their life experiences and the specific type they have.

synaesthesiabrain
synaesthesiabrain

Scientists describe the mechanism of synesthesia through the relationship between an "inducer" and a "concurrent" experience. The inducer is the initial trigger, such as a sound or a written letter. The concurrent is the additional sensation that follows, such as a color or a taste. Researchers use a specific notation to explain this, using an arrow to show the direction of the trigger. For example, if a person sees colors when hearing musical tones, it is written as tone → (color, movement). These experiences are described as being automatic and ineffable, meaning they happen without effort and are difficult to fully describe in words.

There are two primary ways that these sensations manifest in the mind. The first is projective synesthesia, which is the version most people understand. In this form, the person actually sees colors, shapes, or forms physically located in space. The second form is associative synesthesia. In this version, the person does not see an object in the real world, but they feel a very strong, involuntary mental connection between the trigger and the sensation. For instance, an associative synesthete hearing a trumpet might not see a shape, but they will think very strongly that the sound is "orange."

Booba-Kiki
Booba-Kiki

Many different types of synesthesia exist, and some are much more common than others. Grapheme-color synesthesia is one of the most frequent types. In this version, letters and numbers, known as graphemes, are perceived as having inherent colors. While colors vary by person, studies show commonalities, such as the letter "A" often being seen as red.

Stroop interference
Stroop interference

Another common type is chromesthesia, which links sound to color. People with chromesthesia might see "photisms," which are visual experiences like colors or shapes, triggered by music or environmental noises. For some, music looks like moving lines on a screen, similar to an oscilloscope.

Music, Pink and Blue No. 2, by Georgia O'Keeffe
Music, Pink and Blue No. 2, by Georgia O'Keeffe

Other forms of synesthesia are much rarer and involve different sensory combinations. Lexical-gustatory synesthesia is estimated to affect only 0.2% of the synesthesia population. This occurs when certain words trigger specific tastes, such as the word "basketball" tasting like waffles. Mirror-touch synesthesia is another rare form where an individual feels a sensation on their own body when they see someone else being touched. There is also emotional synesthesia, which is estimated to occur in only about 1% of synesthetes. In this rare case, emotions can trigger sensations like smell, taste, or texture.

synaesthesiabrain
synaesthesiabrain

The history of studying synesthesia spans several centuries. The earliest recorded mention dates back to 1690, when the philosopher John Locke reported a story about a blind man. This man claimed to see the color scarlet when he heard a trumpet. However, historians debate if this was true synesthesia or just a metaphor. The first official medical account was provided by the German physician Georg Tobias Ludwig Sachs in 1812. Later, in 1881, Francis Galton documented "number form" synesthesia. This involves a mental map where numbers appear in specific locations in space.

Galton number form
Galton number form

Synesthesia has significant connections to other cognitive abilities and fields of study. People with spatial sequence synesthesia, who see sequences like months or days as points in space, may have superior memories. They can often recall past events and details much more effectively than others. Some researchers also look at ticker-tape synesthesia, where people see written words as they are heard, to help explain dyslexia. Furthermore, scientists are investigating whether ASMR, a common sensory sensation, is a form of synesthesia based on how neural pathways connect. While some may find the sensory input overwhelming, many synesthetes view their condition as a gift or an extra sense.

Number Form--colored
Number Form--colored
691 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (8)
File:Number Form--colored.jpg
Number Form--colored.jpg
File:Galton number form.svg
Galton number form.svg
File:synaesthesiabrain.jpg
synaesthesiabrain.jpg
File:Stroop interference.jpg
Stroop interference.jpg
File:synaesthesiatest.jpg
synaesthesiatest.jpg
File:Music, Pink and Blue No. 2, by Georgia O'Keeffe.jpg
Music, Pink and Blue No. 2, by Georgia...
File:Mikalojus Konstantinas Ciurlionis - FINALE (I) - 1908.jpg
Mikalojus Konstantinas Ciurlionis -...
File:Booba-Kiki.svg
Booba-Kiki.svg
More to explore

✨ What else?

Related topics you might enjoy

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.