Synesthesia refers to a perceptual condition characterized by a blending of sensory experiences. For example, for people with synesthesia, specific words may have a flavor, days of the week may have different personalities, or the sound of music may be associated with colors. Synesthesia is not considered to be a disorder and usually causes no ill effects. Read on to learn more about this condition, its history, and some of the various forms of it that have been identified.
Synesthesia: A Definition
In other words, the individual doesn’t have to try to experience these perceptions, and the associations their brain makes (e.g., Wednesday and the color blue) are usually fixed throughout their lives.
In most situations, synesthesia is not considered a disorder. Except in a few rare cases in which an individual complains of synesthesia overload, people with this manner of functioning are generally quite comfortable with it and to live happy, creative, imaginative lives, stimulated by their extra sensation boost.
How Common Is Synesthesia?
As one paper on the topic reports, synesthesia can occur “in response to drugs, sensory deprivation, or brain damage”, or it can be genetically inherited and experienced throughout a person’s life. Those with the genetic form of synesthesia are estimated to make up around 4% of the general population. However, it’s entirely possible that the actual incidence of the condition is higher because many people likely don’t know they have it. For example, a person might be surprised to discover that others aren’t able to pick out the letter “A” as quickly as they can in a letter-identification puzzle because, for others, the “A” does not stand out in the color red as it does for them.
Synesthesia Throughout History
Cases of synesthesia have been reported throughout history. For example, a German poet and philosopher in 1772 mentioned that, “through a sudden onset”, some people could “immediately associate with this sound that colour”. In the mid-1800s, a French physician called this phenomenon “hyperchromatopsie (perception de trop de couleurs)”, referring to it as a “perception of too many colors”. Well-known Swiss psychiatrist Carl Jung mentioned it in one of his books in 1912, noting some people’s “perception of the tonal quality of colours and the chromatic quality of musical tones”. By the 1980s and 1990s, synesthesia had entered the mainstream both in terms of research and popular culture.
Types Of Synesthesia
Synesthesia describes the phenomenon where a person experiences a sensory perception that’s not normally related to the original sense through which they received the stimulus. Beyond this basic description, however, it can take many forms. Estimates on how many forms of this condition may exist range from 50 to 100 or more. Let’s take a look at just a few of these.
Grapheme-color is thought to be the most common form of synesthesia. People who have it generally see certain letters or numbers tinged with colors, or perceive them this way in their mind’s eye. Another variation of this type is "spatial sequence synesthesia”, in which a person sees the grapheme—a letter or number—as positioned differently in space. A seven may be large and close up while a four may seem to be very far away, for example.
Another common form of synesthesia involves seeing colors or colorful shapes while hearing sounds. A person with sound-color synesthesia might see a sparkle of fireworks when a garbage can lid clatters, for instance, or they may see drifting blue smoke when a cat meows. Some people with sound-color synesthesia may only see colors with select, everyday sounds, while others may only experience it music.
Ordinal-Linguistic Personification (OLP)
With this variation of synesthesia, anything that comes in a sequence—such as days of the week, months of the year, letters, or numbers—may be associated in a person’s mind with distinct personalities, genders, and/or relationships. For example, the numbers one, two, and three might be perceived by a person with OLP as children who play together, or March and April might be sisters. Because this isn't necessarily a direct sensory association, though, there’s some debate as to whether it should be classified as a type of synesthesia. However, because it’s involuntary, many researchers feel it should be included in the category.
In this rare form of synesthesia, an individual will “experience phantom tastes when hearing, speaking, reading, or thinking about words”. For example, the word "desk" might taste like gingerbread, or “lantern” like icing. Sometimes, this type of synesthesia can be letter-associative. For example, the letter "C" might taste like chocolate.
Mirror-Touch Synesthesia (MTS)
Mirror-touch synesthesia refers to when a person experiences a phantom bodily sensation when they see another person experiencing one. For example, one well-known study had MTS synesthetes watch someone’s open palm be touched, and they reported feeling a sensation in the same part of their own palm. The reason for this perception is thought to have to do with certain somatosensory regions of the brain, which are active when anyone sees another person being touched. It may simply be that these networks are hyperactive in MTS synesthetes.
When To Seek Help For Synesthesia
Again, synesthesia is not generally considered to be a disorder and doesn’t usually cause any problems. As an expert quoted in the article linked above about hyperactive somatosensory networks puts it, “It’s just an interesting difference, like being double-jointed”. However, there are a few instances in which it may be cause for concern.
First, genetic synesthesia is usually a life-long attribute that first manifests in childhood. If you suddenly begin to acquire synesthesia as an adult, it’s generally recommended that you consult with a doctor. Grapheme-color, sound-color, and number-form synesthesia all manifest as visuals that could be early warning signs of a serious medical condition, since head trauma, brain tumors, certain infections, migraines, seizures, cerebral strokes, and epilepsy can all cause symptoms synesthesia.
Secondly, some people find the additional sensory perceptions they experience with synesthesia to be overwhelming. This can be especially true for those on the autism spectrum, who may experience sensory overwhelm more easily and may also be more likely to have synesthesia. Others may experience self-esteem issues or anxiety around the fact that they perceive the world differently than others. In cases like these, therapy may be helpful. A therapist can help an individual learn to manage the overwhelm they may feel because of synesthesia, and they can also assist them in accepting this unique difference in themselves over time.
If you’re interested in seeking therapy, you can usually choose between online or in-person sessions, since research suggests that the two can be equally effective in most cases. If you have a busy schedule or are unable to commute to and from in-person appointments, you might consider an online therapy platform like BetterHelp, where you can speak with a licensed therapist via phone, video call, and/or in-app messaging from the comfort of home.
How does synesthesia affect everyday life?
While it may seem as though the synesthetic experience might be an overwhelming barrage of sensory information, most synesthetes do not consider their experience overwhelming. Most synesthetes experience the condition very early and grow up experiencing their own version of what sensory data is “normal.”
Synesthetes do not often report discomfort because they are naturally accustomed to their perceptions. In fact, it is difficult to obtain data on how many people are synesthetes because they do not clearly see how their perception differs from others. The relatively low impact of synesthesia is one of the reasons it is not considered a mental illness, although it can interfere with some other mental health conditions.
What are the challenges with synesthesia?
There are very few challenges associated with synesthesia. The challenges that do occur are often in specific populations. For example, individuals on the autism spectrum may experience more adverse effects from synesthesia due to sensory overload. There is also some consideration that synesthesia may make it harder for children to learn complex properties like letters, numbers, dates, and musical notes, but that evidence is limited.
Contradictory evidence also exists, asserting that young synesthetes can leverage their unique sensory approach to overcome cognitive and physiological constraints during certain tasks. To non-synesthetes, it may seem as though synesthesia is an overwhelming sensory experience, but synesthetes adapt at a young age. Evidence suggests they are rarely adversely impacted by their condition.
Can a person have more than one type of synesthesia?
Several types of synesthesia have been identified, and evidence suggests that it is possible to have more than one. Research indicates that some common subtypes of synesthesia, like sound-color (also called colored hearing) or lexical-gustatory, may actually be clusters of other distinct synesthesia types. The research further indicated that some types, like mirror-touch synesthesia, don’t fall cleanly into any category and may represent different interpretations of several sensory modalities. It can sometimes be difficult for a person to determine exactly what type of synesthesia they have; one cannot take a universal “synesthesia test” to provide answers.
Can synesthesia be influenced?
Synesthesia is a neurological condition that is unintentional, uncontrollable, and nonconcious. The sensory stimuli that elicit synesthesia’s effects are called inducers, and the connection between certain sensory experiences and an inducer is an automatic process. For example, upon hearing a sound (the inducer), a person with sound-vision synesthesia would simultaneously and automatically see the sound as well. They cannot stop themselves from “seeing” the sound any more than a non-synesthete could prevent themselves from hearing it.
The only way to influence synesthesia is likely by controlling which inducers a synesthete encounters. Non-synesthetes often think of synesthesia as “extra” sensory information, but to a synesthete, the complete sensory experience produced by an inducer is typical and normal. It is not open to influence any more than a non-synesthete’s sensory perception is.
Does synesthesia affect emotions?
Synesthesia can have a profound effect on emotions. One is likely familiar to non-synesthetes; strong sensory perceptions can produce strong emotions. For example, some people are amazed or overwhelmed by the majestic beauty of nature, and almost everyone can experience vivid emotional reactions to sensory stimuli that are unpleasant or horrifying.
Synesthetes may have more opportunities for these strong sensory experiences than the average person. For example, a synesthete with the sound-color variety may experience profound visual imagery when listening to music, which could produce a strong emotional reaction due to the visual stimuli, beyond what would be experienced with auditory stimuli alone.
There is also a subset of synesthesia called emotional synesthesia, wherein a specific sensory input is consistently associated with a certain emotional response. Emotional synesthesia is less understood than other types of synesthesia, which are themselves still the subject of intense investigation. However, early evidence suggests that emotional synesthesia may impact how a person processes and interprets their thoughts and feelings.
How does synesthesia affect perception?
Synesthetic perception is characterized by synesthetic experiences, which are concurrent activations of two or more senses by one stimulus, known as an inducer. For example, consider a person with sound-color synesthesia who simultaneously experiences sound and color sensations. Sound-color synesthetes typically associate certain sounds (inducers) with specific colors; upon hearing a sound, they also "see" it. They might hear music played on a piano as bright purple, while the sound of a passing garbage truck might be greenish-brown.
Although it may seem that synesthetes are constantly inundated with extra sensory information that might be overwhelming, most people with synesthesia develop the condition early on and grow up thinking their sensory experiences are typical. Because their brains adapt early, most do not experience problems with perception.
Do all people with synesthesia see the same things?
Synesthetes all likely experience different sensations. One piece of synesthesia research identified over 24 different subtypes, although five to seven types are more widely accepted. For example, those with auditory-tactile synesthesia experience the sensation of being touched when hearing sounds, while synesthetes with grapheme-color synesthesia tend to see letters and numbers as certain colors.
Individual experiences can vary within subtypes as well. Grapheme-color synesthesia is considered one of the most common types, but not everyone experiences the same associations. One person might associate a certain sound with the color red, while another person associates the same sound with an iridescent purple.
Can synesthesia be beneficial?
Evidence suggests that synesthesia may offer benefits during certain tasks of perception. Anecdotal evidence has long supported the conclusion that those with synesthesia tend to be more creative, intelligent, or open to new experiences than non-synesthetes, but the evidence is inconclusive. One study did find that synesthetes scored higher on some measures of creativity, as well as scoring higher on cognitive abilities like verbal comprehension or mental imagery. However, the study found that the effects were much weaker than earlier studies suggest, indicating that further research is required to determine what benefits synesthesia imparts, if any.
Is synesthesia inheritable?
Synesthesia is considered to have at least some heritability. While it is still difficult to estimate how many people have synesthesia, estimates suggest that as many as 4% of individuals meet the criteria for the condition. It is relatively rare, yet one study found that around 40% of synesthetes report having a first-degree relative with the condition. This suggests that genetics play a role in synesthesia, but genes aren’t the whole picture. At least one study found a pair of identical twins - who share almost identical genes - where one twin had synesthesia, but the other did not, suggesting that genetics are not the only factor relevant to the development of synesthesia.
Is synesthesia related to intelligence?
There is some evidence to suggest that many synesthetes score higher on measures of intelligence than non-synesthetes. Early research indicated generally higher scores across all cognitive domains, but later research suggested that synesthetes tend to have cognitive strengths in verbal comprehension and mental imagery. While there appeared to be a clear link between intelligence and synesthesia in early studies, contemporary research has found a much weaker correlation, suggesting that more research is required before meaningful conclusions can be reached.
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