Synesthesia: Definition, Explanation, And More

Updated May 25, 2023by BetterHelp Editorial Team

Curious About Synesthesia?

Synesthesia is known as a phenomenon that can occur when people enjoy “extra” or unrelated senses being activated in response to stimuli.

Understanding the different types of synesthesia can support those who live with it by creating an environment with a higher degree of empathy and understanding. Read on to learn more about the different types of synesthesia and what one may experience with each.

What Is Synesthesia?

So, what does someone with synesthesia experience? Reports may vary depending on the person’s individual experiences and the type of synesthesia that they are living with, 

For example: Some people can “see” music. This means that they can hear music as it sounds to others, but they can also visualize the specific sounds based on the auditory stimuli they’re experiencing.
There are many different types of synesthesia that one may experience. Understanding the different types can often be the first step to validating your experience if you believe that you are currently living with synesthesia. 

What Causes Synesthesia?

At the time of this publication, there is not a singular identified cause of synesthesia. Many people in the scientific community believe that the condition may be caused due to neurons in the brain firing in response to stimuli, potentially triggering synapses in nearby neurons. It may also be genetic, according to some studies.

Scientists believe that an estimated 2-4% of the population may have synesthesia, but acknowledge that there could be many more undiagnosed people. New research with functional magnetic resonance imaging (fMRI) currently supports the idea that individuals living with synesthesia experience a dramatic increase in the area of the brain responsible for sight when the participant is subjected to certain stimuli. Another test referenced in the linked study showed that sensory receptors might just be more active in some individuals, giving them the appearance of an “extra sense.”

Different Types Of Synesthesia

A person who experiences any type of synesthesia can be considered a synesthete. No matter what kind of synesthesia one has, it is generally believed that no two people experience it the same way. Science currently supports the hypothesis that there are two basic, basal forms of synesthesia — which are known as associative and projective types, respectively.

Associative Synesthesia

Associative synesthesia, can cause those who have it to associate certain colors with numbers, letters, sounds or tastes. They do not smell, feel, or see them in many cases, often simply perceiving their presence. 

For example: Some who have this condition may see the letter A written in black ink as blue in their head, but they can still see it in black as well.

To these individuals with associative synesthesia, there can be a connection between the stimuli and the sense that is activated, even if it cannot be seen or explained.

Projective Synesthesia

Synesthetes with projective synesthesia may see shapes, forms, or colors when they hear, smell or taste something. They may also actually taste, smell, feel, see or hear things that are supposed to be experienced by a different one of their senses. 

For example: People who live with this form of synesthesia may be able to see a sound, or taste a word. For them, the sound of a guitar may cause them to see the color orange. In contrast, those with associative synesthesia might just feel or know that the guitar sounds orange without really “seeing” it.

There is a general consensus that there are over 20 variations of synesthesia, all of which crossing across projective and associative basal types. Each variation is generally associated with stimulating a unique set of senses in response to perceived stimuli. 

We’ve summarized a range of synesthesia subtypes below.

Grapheme-Color Synesthesia

This is statistically suggested to be one of the more common variations of synesthesia. Those with grapheme color synesthesia who live with the projective subtype may see numbers or letters as certain colors. 

Those with associative synesthesia may perceive that the number or letter is a certain color without seeing it.


Those who have chromesthesia may see colors when they hear certain sounds. For instance, a dog barking may cause the synesthete to see the color green, based on whatever previous association has been stimulated or established. While projective synesthetes might see the color green in real life, associative synesthetes may simply associate that sound with the color.

Spatial Sequence Synesthesia

Synesthetes living with spatial sequence synesthesia may see numbers at different points in space. For example: A person living with this condition may perceive the number one as a “closer” integer than the number two — but for others, it may be the other way around. 

Another example commonly lies within the year, month, and day format, in which the year 2010 may be to one’s “right,” while Tuesday is “above” your head.

Number Form Synesthesia

Someone with number form synesthesia can visualize a map of different numbers in a certain order when they think about numbers as a concept. This can be similar to spatial sequence synesthesia, but those with this condition might see the numbers in order in a line rather than perceiving their set point.

Auditory Tactile Synesthesia

This type of synesthesia can cause certain sounds to stimulate a sensation in part of your body. In other words, if you have auditory, tactile synesthesia, you may have a link between the sensory connections that dictate your sense of hearing and your sense of touch. 

Mirror-Touch Synesthesia

Mirror-touch synesthesia can range from being able to feel other people's emotions to experiencing others' pain or another physical feeling they may have — similar to a form of severe empathy. 

For example: If you see someone touch your friend on the back, and you feel a touch on your back even though nobody is there, you may have mirror-touch synesthesia. People with this form of synesthesia can be so affected by other people's feelings that they may isolate themselves to avoid feeling overwhelmed by what others feel. 

Curious About Synesthesia?

How Can Online Therapy Help Those Who Live With Synesthesia? 

Online therapy can be a helpful resource to those who live with synesthesia. For example: If someone were to have trouble leaving home or traveling for any reason, online therapy can be a helpful option to consider. 

Generally, one could reach out to their counselor anywhere that they’re comfortable as long as they have a secure, reliable internet connection. Also, online therapy may be more affordable than traditional therapy for some.

Is Online Therapy Effective For Those Experiencing Synesthesia? 

At the time of this publication, there’s no single treatment option for those living with synesthesia. Despite this, therapy can still be a beneficial treatment option. In fact, 75 percent of people who have done psychotherapy report some kind of benefit. This can offer promise to some, especially those who are looking for new coping mechanisms and supportive strategies to navigate synesthesia with. Your therapist can create a plan that speaks to your specific needs.

Dealing With Synesthesia

Are you or someone you know experiencing any of these feelings? Or maybe you are concerned about something else that you are experiencing. 

With BetterHelp, you can talk to a licensed professional without even having to leave home or set an appointment. Just click on this link and answer a few simple questions and you can be talking to someone helpful in no time.


There can be many types of synesthesia, and in most cases, no two individuals experience it in the same way. For example, some may experience auditory tactile synesthesia through which they feel sounds — and others may experience spatial sequence synesthesia in which they see numbers spatially. Synesthesia is typically not threatening, but if synesthesia is causing difficulties in your life, then online counseling can help. BetterHelp can connect you with a therapist in your specific area of need.

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