Understanding The Developmental Aspects Of Synesthesia

Synesthesia is a relatively rare sensory phenomenon that has been the subject of much curiosity and research over the years. This term refers to a person’s innate neurological style of experiencing different senses simultaneously, such as hearing colors or tasting shapes. It’s not considered to be a medical or mental illness; it’s simply a different way of perceiving the world. 

Although it's been studied for many years, there are still plenty of unanswered questions about synesthesia—particularly about how it may develop throughout a person’s lifespan. Below, we’ll explore some key findings from recent studies on synesthesia and consider what they can tell us about this unique sensory experience.

Synesthesia defined

The American Psychological Association describes synesthesia as a trait in which “stimulation of one sense generates a simultaneous sensation in another,” noting that these sensations are automatic, uncontrollable, and vivid. There are at least 50 different synesthesia types, or ways it may manifest. Some examples include:

• Grapheme-color synesthesia is one of the most common types and involves seeing colors associated with specific numbers, letters, or words on a page or screen, such as the letter J always being turquoise
• Chromesthesia, where a person sees colors when they hear sounds—a type sometimes associated with musicians
• Mirror-touch synesthesia, which includes feeling the sensation of touch when seeing someone else being touched
• Number-form synesthesia, where an individual will mentally perceive or envision numbers in a fixed shape, arrangement, or diagram
• Auditory-tactile synesthesia, meaning that sounds produce certain tactile sensations in a person’s body, such as a car horn feeling like scratches on the skin or a whispering voice feeling like a fuzzy blanket

What causes synesthesia?

Synesthesia often initially presents itself very early in a person’s life—typically around age four or five. However, the number of synesthetes has been reported to decrease among populations of children even by age 10, suggesting that although this trait likely has a genetic component, environment may play a role in its development as well. While synesthesia’s exact causes and mechanisms are not fully understood, research indicates that it may be a result of some people being born with more synaptic connections than others, allowing information—including sensory information—to travel within the brain more efficiently.

For example, a person with synesthesia might experience sound vibrations as colors or shapes due to information from one brain area being linked with another. 

Finally, it’s also worth noting that some research has linked the trait of synesthesia to various other forms of neurodivergence as well as some mental health conditions. For example, a 2021 report indicates that synesthesia is more common among individuals with an autism spectrum diagnosis. Another study suggests that synesthesia may have a link to certain anxiety disorders like obsessive-compulsive disorder. That said, synesthesia on its own is still generally viewed as a “benign” trait rather than an illness, and more research is needed into any potential relationships to diagnosable disorders.

How synesthesia may change over a person’s lifetime

Given the aforementioned research that suggests that the number of identifiable synesthetes seems to decrease over time, it would seem that the intensity of this phenomenon may also decrease over time. However, there are other potential explanations. 

As one study puts it, the associations between numbers and colors or other linked senses may simply become more complex and subtle as people age. In adulthood, for example, some synesthetes report experiencing synesthetic experiences that are more abstract than simple color associations. Or, as another study reports, synesthetic perceptions may actually increase with age due to a greater understanding of language and experience gained over time. Still others believe that the intensity of synesthetic perceptions may gradually decrease due to the natural degradation of the physical brain over time. These mixed findings may illustrate the complex nature of the mind, the individuality of each person’s experience, and the need for more research.

One study’s findings on synesthesia development

A study conducted in 2017 screened 4,000 members of the general population to identify grapheme-color synesthetes in particular to gain insights about its manifestations at different ages. Before this study, there was virtually no research on how synesthesia may change throughout a person’s lifespan. It unearthed a few key findings.

First, a key component of the definition of synesthesia throughout history has been the consistency of the associations. For example, a synesthete who associates the number seven with the color lilac will report the same association again and again over time, a phenomenon which has historically indicated that synesthesia is a fixed, consistent mental trait. In fact, testing for this consistency is often how an individual is ‘proven’ to have synesthesia. However, this newer study on adult synesthetes indicates that this consistency may fade over a person’s lifetime, potentially changing the way scientists think about this trait and its causes.

There are two potential reasons for this change over time. First, associative memory (the type of memory that allows us to remember that two things are linked together, like matching a face to a name) and chromatic discrimination (one’s sensitivity to differences in color) are thought to fade with age as part of mild, natural cognitive decline. Second, the study reports, synesthesia is generally associated with higher connectivity in the white matter of the brain and increased gray matter overall, both of which decline in adults in general as they age. The results seem to be that the number of identifiable synesthetes declines as populations age, and those who maintain this trait report a more limited bandwidth of color associations (primary colors only rather than the more nuanced shades younger people tend to report) over time.

Finally, it’s worth noting a key limitation of this and any other synesthesia study, one of which is the difficulty of finding participants. Researchers report posting advertisements seeking out those who experience synesthesia, but note that this may only attract those with “relatively strong synesthesia,” limiting the sample’s size and diversity. Regardless, this study is impactful because it calls into question what has previously been considered a key trait of synesthesia—its consistency—inviting researchers in this area to reconsider, once again, the way they view this neurological difference and the functioning and aging of the human brain overall. 

Living with synesthesia

For those living with synesthesia, this heightened sensory experience may offer extra creative potential, allowing them to perceive connections between seemingly unrelated things in unique ways. However, synesthetes may also be at an increased risk of feeling isolated and different from others due to their unusual experiences, which may lead to a sense of alienation, trouble fitting into social circles, and perceiving that others can’t relate to or understand their point of view. 

Synesthetes may also find it challenging to communicate their experiences due to the inherent difficulty in describing abstract perceptions, such as color associations with sound or smell combinations with taste. It’s possible too that they may sometimes experience sensory overload due to the volume and complexity of their sensory input. 

Seeking support for synesthesia

If you have synesthesia and are troubled by some element of your experience, support is available. Those who are simply seeking community and validation of their experiences might seek out forums or even support groups. Those who feel isolated, frequently overwhelmed, or confused about their perceptions may benefit from seeking the support of a mental health professional, as may those who have synesthesia and are also experiencing symptoms of a mental health condition. A therapist, for example, can offer you a safe space to express your emotions and make sense of your experiences as well as share coping mechanisms for difficult feelings or sensory overwhelm. 

If you find that meeting with a therapist in person is overwhelming to your senses or simply doesn’t fit your schedule, you might consider online therapy. Through a virtual therapy platform like BetterHelp, you can get matched with a licensed therapist in a matter of days. You can then meet with them via phone, video call, and even in-app messaging to address the challenges you may be facing, all from the comfort of home. Research suggests that there may be no difference in effectiveness between online and in-person therapy sessions in most cases, so you can generally feel confident in choosing either method.