Synesthesia: A Fascinating Neurological Phenomenon

"Music is the color of the rainbow and roses smell blue." Synesthesia is one of the most amazing neurological phenomena and each individual experiences it in a different way. Find out more here.

Written and verified by the psychologist Valeria Sabater.

Last update: 21 July, 2024

Smelling the music. Feeling that colors make sounds. Reading and perceiving that certain letters are blue, red, or yellow. Synesthesia is one of the most amazing neurological phenomena. It tends to be associated with creativity and has been linked with figures like Vincent van Gogh. However, at times, it can be a somewhat disturbing experience.

Being synesthetic is rather like having a mind with multiple parallel universes that react in unexpected ways. Any stimulus can suddenly trigger arbitrary sensory experiences, almost as if there’s a bug in the brain. There’s an excess of neural connections which leads to failures and alternations in the processing of information.

This characteristic is called multimodal integration and defines only a small part of the population. In this article, we’re going to tell you all about it.

Synesthesia

Synesthesia is a neurological condition in which the stimulation of one sense triggers another. Research published in the journal, PLoS Biology suggests that the incidence is between two and four percent of the population. They define the experience as one in which a stimulus causes unexpected sensations, such as hearing colors or tasting words.

The authors of the same investigation emphasize that the origin of the phenomenon has a specific neural basis. Cross activation or, as mentioned, multimodal integration is always present. There’s an excess of neural connections which causes several senses to be activated at the same time when a stimulus is processed.

It’s known that synesthesia has a genetic basis. In fact, it’s handed down from parents to children. There’s some interesting research published in the journal, PNAS regarding the origin of this excessive connectivity. It claims the key lies in genetic alteration. This would explain, for example, that, in one family, they might all exhibit the same variety of sound-color synesthesia.

The main types

Amazingly, there could be around 164 types of synesthesia. At least this is what a study conducted by the University of Sussex (UK) suggests. Moreover, the combinations that the crossings between the different senses and stimuli can generate are amazing.

To analyze them correctly, they must be grouped. This reduces the number of them somewhat. One particularly curious kind is personality synesthesia. With this type, the individual sees different people in different colors.

Next, we’re going to explore the different kinds of synesthesia.

Grapheme-color synesthesia

In grapheme-color synesthesia, the individual might see the letter A as blue and the letter B as green. Each letter evokes a particular chromatic tone. The University of Edinburgh (UK) conducted a study that was published in the journal, Frontiers in Human Neuroscience. It describes an interesting investigation conducted with 600 random children, to discover how this type of synesthesia evolves over the years.

Auditory-visual synesthesia

Auditory-visual synesthesia is also known as chromesthesia.  It’s a condition in which the individual sees colors when listening to music or random sounds. It’s an intense and exhilarating experience. In fact, it’s defined many notable artists like Paul Klee and Wassily Kandinsky, and, more currently, the singer, Lady Gaga.

Lexical-gustatory synesthesia

Can you imagine, when speaking, reading, or hearing certain words you ‘taste’ them? For instance, the word ‘house’ might taste like strawberry ice cream or mint tea. Lexical-gustatory synesthesia causes the individual to feel flavors when they’re exposed to auditory stimuli. Specific neurological facts make those who show this condition unique.

Mirror-touch synesthesia

Mirror-touch synesthesia is particularly fascinating. It means one individual might have the same physical experience as another person they’re observing. For instance, if they’re with a friend who scratches their forehead, they also feel the touch of their fingers on their head. Or, if they see a movie where an actor caresses an actress, they also feel it.

The touch-sound modality

Touch-sound or audio-tactile synesthesia involves the interesting phenomenon of experiencing sensations when listening to sounds. It’s similar to the classic ASMR. Sometimes, when the affected individual exposes themselves to certain music or sounds, they feel ticklish caresses as if a feather were being stroked over their skin.

Tickertape synesthesia

Tickertape synesthesia would be hard to believe if there weren’t scientific documentation to support it. The journal, Cognitive Neuroscience, details this typology. These people, when thinking or listening to others speak, see in their minds subtitles or physical words transcribing those auditory experiences.

The authors claim that this is a type of synesthesia in its own right and that it’s not related to grapheme-color synesthesia.

What are people with synesthesia like?

Synesthesia is an interesting experience due to several aspects. Firstly, it’s one of the most striking non-pathological neurological phenomena. Secondly, it’s common for those affected to exhibit the characteristic of creativity.

The University of Bern (Switzerland) confirmed this idea in a study. They claim that there’s a link between being a synesthetic individual and dedication to art. It seems that those who stand out the most in these areas are those who demonstrate the auditory-visual typology.

Indeed, it seems that those who, when exposed to auditory stimuli, see extraordinary colors around them, become more involved in creative tasks. They demonstrate divergent creativity to a greater degree. This means they exhibit a more innovative, challenging, and non-linear way of thinking.

Today, there’s new scope for synesthesia in the future. In fact, investigations such as those published in the journal, Nature state that, although this neurological condition is congenital, it can be learned. An interesting fact, indeed. After all, who wouldn’t like to have a synesthetic experience?