Types of Synesthesia

If you’ve heard of synesthesia, you might know that it can involve hearing colors in response to sound. While this is a common experience, it’s only one of many possible manifestations of this multi-dimensional sensory phenomenon. Synesthesia can involve links between a wide range of perceptions and senses. In this article, we’ll introduce you to the many different types of synesthesia that have been identified to date and how they can impact an individual’s life.

What Is Synesthesia?

The associations that people with synesthesia (called synesthetes) experience are often highly stable over time. A synesthete who perceives the letter H as rough and sandpapery and the letter P as rubbery and flexible may experience those associations throughout their entire lifespan. This is not always the case, though; a 2012 paper reported that as many as 17% of synesthetes might experience changes in the type, frequency, or intensity of their non-typical perceptions over time. 

It Can Take Many Forms

Synesthesia is thought to manifest differently in different people. Although two individuals might experience tastes in response to sounds, one may link the musical note C# with a lemony flavor while the other has the synesthetic perception of vanilla. 

People with synesthesia can be classified as projectors or associators. Projector synesthetes report vivid sensory effects that appear to exist in space rather than in their minds. For example, if they are looking at the page of a book, they might see the individual words or certain letters brightly highlighted in different colors.

Associators may not have such strong external perceptions. Instead, they might have strong mental links between particular sensations or concepts. An associator synesthete might think of the idea of Wednesday as fuzzy and friendly, but they wouldn’t actually feel its hair brushing against them when looking at that day on a calendar. A 2005 overview of individual differences in synesthesia estimated that most synesthetes are associators while only about 10% of synesthetes are projectors.

What are the Known Types?

Grapheme-Color

In some cases, a person with this type of synesthesia will see each letter of a word in a distinct hue, while others might find that entire words take on the color of the first letter. This latter type is considered by some to be a separate kind of synesthesia known as lexical-color synesthesia.

Number-Form

People with this type of synesthesia report that they experience numbers within a kind of mental shape or diagram. When they think about numbers, they may consistently see specific values at particular points within this imagined structure. These forms don’t always follow an obvious logic, but they may still enhance performance on certain mathematical tasks.

Lexical-Gustatory Synesthesia

Spatial Sequence Synesthesia (SSS)

This type of synesthesia involves items in an ordered list appearing to occupy positions in space. For example, certain months might seem closer or farther away depending on where they fall in the year. Other people might experience the hours of the day in a clock-like arrangement around their bodies. Number-form synesthesia may be just one type of SSS that relates specifically to numerical sequences.

Chromesthesia

This is the technical term for seeing sounds as colors, sometimes with accompanying shapes or motions. These visual elements typically accompany the sounds rather than replacing them, and people with this type of perception often find that it enriches the experience of listening to music. Many notable recording artists have claimed that they have chromesthesia, and that it’s helped them in their creative work.

Mirror-Touch

Tickertape

Ordinal-Linguistic Personification (OLP)

Like spatial-sequence synesthesia, OLP affects the perception of items in lists or sequences. But rather than locations in space, they’re perceived as people, possessing distinct personality traits and sometimes genders. This can involve fairly detailed ideas—one researcher interviewed an individual who perceived the letter I as “honest and well-intentioned, but dictatorial and overbearing”.

Auditory-Tactile

In this form of synesthesia, specific sounds can produce tactile sensations in various parts of the hearer’s body. Different types of music might provoke different levels of pressure, or some spoken words might feel prickly while others seem smooth or soft. 

In some cases, this can be unpleasant, with some individuals reporting that certain songs or voice qualities produce uncomfortable sensations. Others may find their synesthetic responses enjoyable. There’s evidence that the phenomenon of autonomous sensory meridian response (ASMR)—in which certain sounds produce a pleasant tingling sensation in some people—might be linked to auditory-tactile synesthesia.

How Online Therapy Can Help

Synesthesia is not considered a mental disorder, but it may be more common in people with conditions like post-traumatic stress disorder and anxiety disorders. Studies show that online therapy can help those who are experiencing such disorders, along with a range of other mental health challenges. In a meta-analysis of over 90 studies, with almost 10,000 total participants, researchers found that online therapy was as effective as face-to-face treatment, specifically mentioning its efficacy when addressing post-traumatic stress disorder and anxiety disorders.

If you’re experiencing unusual sensations that are causing you distress, or if you find that synesthetic experiences are making it difficult for you to relate to others, you might want to talk with a mental health professional. Online therapy platforms like BetterHelp can make it quick and easy to connect with a therapist who has relevant experience or training in challenges that may be associated with synesthesia. Many clients also find that receiving counseling remotely is more convenient since it can take place anywhere with an internet connection.