Synesthesia, also spelled synaesthesia, is a neurological trait in which a single sensory input automatically triggers a second, involuntary sensory experience. Someone with synesthesia might see colors when they hear music, taste a flavor when they read a word, or link every day of the week to a specific color. It affects an estimated 4% of people and is not a disease or mental illness. Have you ever heard music that tastes like rain? If so, you might be a synesthete, someone whose senses are cross-wired in a consistent, lifelong way.
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What Is Synesthesia?
Synesthesia is when one or more sensory experiences are experienced at the same time in response to a trigger for only one sensory experience. You may hear music that creates images in your mind, or you may see certain words or numbers as a specific color or shape. The brain may route the information through more than one sensory experience, so rather than just hearing a song, you hear it but also taste or feel it.
It is a neurological trait, not a disease or mental health condition, which means it involves the nervous system rather than signaling illness. This happens because the different senses are connected in an involuntary way. Someone who experiences a specific taste when hearing music, for example, experiences this involuntarily.1
Synesthesia can be associated with increased cognitive abilities, as well as creative outlets. Those with this condition can sometimes be able to remember information and complete cognitive tasks that those without this condition can not complete.1
How Does Synesthesia Work?
Synesthesia works by giving input through more than one of the five senses of touch, sight, smell, sound, and taste. When someone with synesthesia receives information through one of these five senses, their brain can mediate more than one sense.
Synesthesia works in the order of:
- Detection: The brain picks up sensory input from one of the five senses, either sound, smell, temperature change, or something else.
- Signaling: The sense is sent to the brain, and the brain interprets it. For example, stepping on something sharp or seeing something bright will send signals to the brain about what is being felt or seen.
- Processing: Next, the brain interprets this information and processes it for you. Seeing a brightly colored object has no meaning until your brain tells you that this is a traffic cone, for example, which has a cautionary meaning once processed by your brain.
What Are the Primary and Secondary Effects in Synesthesia?
The brain of someone with synesthesia processes senses with two main steps, primary and secondary. The senses will send information to the brain about what they are experiencing, and then the brain interprets that information to create meaning.
One way to think about synesthesia includes:
- Primary effect: The immediate sensory input is the primary effect: the feel of something you touch, how something looks or smells, for example.
- Secondary effect: The secondary effect is when the individual may taste something bitter when they see the word “exit” even though they have not put anything in their mouth.
How Many Forms Of Synesthesia Are There?
There are at least 60 known forms of synesthesia, and some researchers estimate more than 150.2 Although this condition has been around for centuries, it has only recently been studied by medical professionals and researchers.3 Some of the most common forms involve the major senses of sight, hearing, and touch and a pairing of these three senses.
Some pairings of three senses common in synesthesia include:
- Sight: Shapes, patterns, and colors
- Hearing: Tempo, rhythm, volume, and pitch
- Touch: Textures, pressure, temperatures.
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What Are the Most Common Types of Synesthesia?
Synesthesia takes many forms, and each type is defined by which two senses become linked.2 One of the most common is sound-to-color synesthesia, where certain sounds cause a person to see specific colors or shapes. Researchers are still unsure how many forms of synesthesia actually exist.4
Auditory-Tactile Synesthesia
Auditory-tactile synesthesia is when certain sounds will evoke specific tactile feelings. For example, hearing the sound of music will cause the person to experience pressure or a feeling of softness.
Day-Color Synesthesia
Day-color synesthesia is when someone associates each day of the week with a specific color. For example, Tuesday is seen as blue, or Friday is seen as pink. The specific color associated with the day might stay constant throughout the person’s life. This means that Friday will be seen as pink, for example, even decades later.
Grapheme-Color Synesthesia
Some people are able to see colors at the same time as numbers. This form of synesthesia is when specific numbers or letters are experienced along with specific colors that they represent. For example, the number 3 may evoke the color green.5
Hearing-Motion Synesthesia
Hearing-motion synesthesia is where individuals will receive auditory input at the same time as seeing motion. For example, they may hear a loud smacking sound when seeing someone walking or running.4
Mirror-Touch Synesthesia
When someone is able to physically experience the sensations that they are watching happen to someone else they have mirror-touch synesthesia. For example, they are able to feel the touch of someone hugging or even hurting another person.4
Time-Space Synesthesia
When someone is able to visualize large mappings of numbers, dates, or other information, this is time-space synesthesia. The person’s brain is able to visualize the information in a specific way, allowing them to remember or visualize large amounts of information such as calendar dates or large numbers.
Visualized Sensations
Visualized sensations is a form of synesthesia where someone is able to experience visual stimuli at the same time as experiencing physical sensations. For example, they may experience a specific color or shape when shaking someone’s hand or when petting a cat.
Can Synesthesia Have Different Levels Of Intensity?
Like all neurodiversity, synesthesia is experienced differently among all people. Experiences will vary in terms of intensity, as well as duration of experiences of stimuli. While experiences will vary, synesthesia might be stable over the person’s lifetime, so if they see the color green when they hear the word “chair,” this same experience will happen a decade later.6 People who take in this extra sensory input can be more prone to sensory overload in loud or visually busy settings, and heightened noise sensitivity can overlap with synesthesia when sounds trigger colors or textures.
What Causes Synesthesia?
Synesthesia has genetic and neurological roots and usually develops in early childhood.7 It runs in families, and about 40 to 50% of synesthetes have a first-degree relative who shares the trait.12
While there are some other factors that can lead to synesthesia, such as substance use or changes within the brain, these are more rare and inconsistent than genetic-linked synesthesia.
Developmental Synesthesia
Developmental synesthesia is a neurodivergence. There is a strong link between synesthesia and autism, which is another neurodivergent condition that is developed in infancy or childhood.4 Research suggests synesthesia occurs at least three times as often in autistic people as in the general population.13
The main element of developmental synesthesia is that it is likely to remain consistent and stable, or unchanging, throughout the person’s life. Unlike other forms of synesthesia that may be brought on by substances or brain changes, for example, developmental synesthesia will remain mostly unchanging.4, 6
Acquired Synesthesia
When someone experiences changes to the brain, such as through brain damage or a traumatic brain injury, they can develop acquired synesthesia.
It has also been found that some of the changes that occur in the brain from substance use can also provoke acquired synesthesia.11
Drug-Induced Synesthesia
Drug-induced synesthesia is also thought of as acquired synesthesia.11 Because of their effect on the brain, there are specific drugs, especially hallucinogens, that can induce synesthesia.8 Some common ones are ketamine, MDMA, Peyote, and LSD.
Please do research and use caution before using any drugs or substances that have the ability to affect the mind or brain, due to dangers and risks associated. Drug dosing should always be under the support and care of a licensed medical professional for safety.
Some examples of drugs that induce synesthesia include:8
- LSD
- Peyote
- Marijuana
- MDMA
- Ketamine
- Mescaline
- Psilocybin
How Is Synesthesia Linked to Other Neurodivergent Traits?
Synesthesia often appears alongside other neurodevelopmental and psychiatric traits, not just autism. A 2025 twin study from Karolinska Institutet, published in Translational Psychiatry, found that self-reported synesthesia in 18-year-old twins correlated with eight different features: autism, ADHD, obsessive-compulsive traits, anxiety, depression, psychotic-like experiences, eating disorder features, and hypomania. The strongest link was with obsessive-compulsive features.14 This does not mean synesthesia causes or is caused by these conditions. It means they tend to cluster, likely because they share some of the same genetic and developmental roots.
Earlier work from the same research group, published in Proceedings of the Royal Society B in 2023, used classical twin modeling to show that synesthesia is substantially heritable and shares genetic influences with autistic traits.15 Together, these studies reframe synesthesia less as an isolated quirk and more as one expression of a broader neurodivergent profile. Because synesthesia involves the senses working in unusual ways, it is sometimes confused with sensory processing disorder, though the two are distinct. For most people this clustering has no negative impact. It matters mainly for context: someone exploring a synesthesia diagnosis may also recognize other neurodivergent traits, and a clinician who understands the overlap can offer more informed support.
How Is Synesthesia Treated?
There is no specific therapeutic or medical modality for treating synesthesia. Many who have this condition advocate for empowering oneself by learning more about it, as well as surrounding yourself with others who are supportive and understanding.
Can Synesthesia Be Prevented?
Due to its genetic component, it is not likely that synesthesia can be prevented if it comes from someone’s development. However, like any neurological condition, substance use can often make the experiences and symptoms worse, so avoiding substance use can help to prevent worsening of the condition.
Can Synesthesia be Learned?
Synesthesia is most commonly developed in childhood, and can be present throughout the person’s life.9 However, some people think that they can teach themselves synesthesia traits by learning to associate specific words or sights with specific colors or images.
While there is some evidence that some people can learn this trait, “Synesthesia is commonly classified as developmental and acquired.”11
How Rare Is Synesthesia?
Synesthesia affects about 4% of the population, roughly 1 in 27 people, and it tends to run in families because of its genetic basis.6
What Is The Rarest Form Of Synesthesia?
The rarest form of synesthesia is thought to be Lexical-gustatory synesthesia, which is when the experience of hearing a word results in tasting a flavor at the same time. For example, hearing the word “car” might taste like mint.10
Is Synesthesia A Mental Illness?
Synesthesia is not a mental illness, but a neurological condition that is often referred to as a neurodiversity, often resulting from development or acquired due to brain changes.11 Unless this condition causes the person a great deal of stress or impairs their life in some way that makes things difficult, there is no need to seek help. Many synesthetes use their condition as a strength!
When Should You Seek Help for Synesthesia?
If your condition is causing you stress or impairing your life in ways that make it difficult to live a fulfilling professional or personal life, it may be time to seek professional support.
An online therapist directory or online therapy platform is a good choice for finding a therapist who specializes in neurodivergent issues such as synesthesia. Similarly, online psychiatrist options are a good choice for finding neurodivergent medication management if this is something you may need.
In My Experience
“In my experience, many of my clients who are neurodivergent, and who have traits of autism, will report experiencing traits of synesthesia. The most common ones experienced are associating days of the week or numbers with specific colors. Unless this condition causes you stress or impairs your life in some way, there is no need to be ashamed. Embrace who you are and use it as a strength!”
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Frequently Asked Questions
What is the most common type of synesthesia?
Grapheme-color synesthesia is the most commonly studied and reported type, affecting roughly 1% of people. In this form, letters and numbers automatically appear in specific colors, so the number 3 might always look green. Sound-to-color synesthesia, where sounds or music trigger colors, is also common. Most synesthetes experience one or two consistent types rather than many at once.
Is synesthesia a superpower?
Synesthesia is not a superpower, but it is often an asset. It is linked to heightened creativity and stronger memory, and many artists, writers, and musicians credit it for their work. It can also be tiring in loud or visually busy settings, where the extra sensory input contributes to overload. Most synesthetes describe it as a neutral or positive part of how they experience the world.
Does synesthesia run in families?
Synesthesia runs in families and has a strong genetic basis. Studies suggest that 40 to 50% of synesthetes have at least one first-degree relative who also has the trait, though the specific form can differ from person to person. A parent with grapheme-color synesthesia might have a child who tastes words instead. Twin research confirms it is substantially heritable.
What does synesthesia feel like?
Synesthesia feels automatic and involuntary, not imagined or chosen. A synesthete does not decide that Tuesday is blue or that the word “car” tastes like mint; the pairing simply arrives with the trigger. These associations are usually stable across a person’s lifetime, so the same letter stays the same color for decades. Most people find their synesthesia natural and often enjoyable.
How do you know if you have synesthesia?
The clearest sign of synesthesia is that a single trigger consistently produces a second, automatic sensory experience, and that pairing stays the same over time. If the letter A has always looked red to you, or music reliably produces colors or textures, you may be a synesthete. Consistency is the key test researchers use. Online consistency tests and a conversation with a clinician who understands neurodivergence can help confirm it.
Synesthesia Infographics
