Synesthesia Examples: Understanding Sensory Phenomena

Synesthesia is a phenomenon that may challenge traditional understandings of human perception and cognition. It can be defined as a perceptual condition in which the stimulation of one sensory pathway leads to another involuntary sensory experience. The most common forms of synesthesia usually involve the blending of senses, such as seeing colors in response to hearing sounds or tasting flavors when reading certain words. This unique merging of sensory experiences may offer a window into the intricate workings of the human brain and highlight the incredible diversity of human perception. While it’s generally not categorized as a disorder, synesthesia can come with mental health challenges for some people. If synesthesia is negatively impacting your mental well-being, consider reaching out to a licensed mental health professional for support.

What is synesthesia?

Synesthesia is generally considered to be a sensory phenomenon in which a person experiences a blending or merging of their five senses. It can be seen as a neurological condition in which the stimulation of one sensory or cognitive pathway triggers involuntary experiences in another. In simpler terms, it can be thought of as a crossing of the senses.

A person with synesthesia, typically called a synesthete, might see colors when they hear music or taste flavors when they see certain shapes or numbers. This condition can create a vivid multisensory experience that is not commonly found in the general population. 

In general, there are many types of synesthesia, and while each person’s experience of synesthesia may differ, research has found some commonalities among those with the same kind of synesthesia.

Synesthesia types and examples

Synesthesia can encompass a wide array of sensory crossover and may involve any number of sensory inputs and outputs, like letters and numbers, colors, sounds, smells, emotions, tastes, and tactile (touch) sensations. Different kinds of synesthesia are explored in more detail below

Grapheme-color synesthesia

Grapheme-color synesthesia usually involves associating specific colors with letters or numbers. For individuals with this type of synesthesia, alphanumeric characters may evoke vivid visual experiences of color. For example, they may consistently perceive the letter "A" as red, "B" as blue, and so on. 

This association of colors with letters and numbers tends to be stable and remain consistent throughout a person’s life. Although more recent evidence may be needed, some synesthesia research has suggested that these synesthetic associations may be rooted in early learning experiences, such as those involving colored refrigerator magnets.

Lexical–gustatory synesthesia

Lexical-gustatory synesthesia is a type of synesthesia in which certain words or linguistic stimuli may evoke specific taste sensations. For example, someone with lexical-gustatory synesthesia might experience the word "table” as having a bitter taste or associate a person’s name with vanilla ice cream. 

These taste experiences tend to be consistent, and the perceived taste may or may not align with the quality of the word. For example, the word “lemon” might not necessarily taste like lemon to a synesthete.

Sound-color synesthesia (chromesthesia)

Sound-color synesthesia, or chromesthesia, generally occurs when sounds, music, or voices elicit the perception of specific colors. People with this type of synesthesia might perceive certain musical notes, chords, or even entire melodies as vibrant hues. For instance, the C note might consistently evoke a brilliant shade of yellow, while the sound of a violin may be associated with a deep purple. 

The colors associated with any given sound may vary widely between individuals, as can the experience of the color. Some individuals may see the color in the physical world, while others may experience the color in their mind’s eye. 

Researchers have found some consistent patterns among sound-color synesthetes. For example, certain pitches tend to be likely to produce similar color experiences among those with sound-to-color synesthesia.

Taste-color synesthesia

Taste-color synesthesia normally involves associating tastes with colors. When someone with this type of synesthesia experiences a specific taste or flavor, they may simultaneously see a corresponding hue in their mind. 

For example, the taste of a strawberry might be perceived as a bright red color, while a tangy lemon might evoke a vivid yellow. However, the color of a particular food may not always correspond to its perceived color for the synesthete, which may make it difficult to enjoy certain foods.

Smell-color synesthesia

Smell-color synesthesia usually manifests as an association between specific scents or odors and colors. When a synesthete with this type of synesthesia encounters a particular smell, it may trigger the perception of a distinct color. For example, the smell of freshly cut grass may evoke a vibrant green color, while the scent of a rose might be accompanied by a soft pink hue.

One study on this type of synesthesia found that the name of the odor was likely to inform the synesthete’s experience, as was its quality. This suggests that, in addition to its linguistic associations, the perceived pleasantness or unpleasantness of smells may inform the visual experience in smell-color synesthetes.

Touch-color synesthesia

Touch-color synesthesia can involve perceiving specific textures or tactile sensations as corresponding colors. A person with touch-color synesthesia may associate a particular color with a texture or tactile sensation. For instance, the sensation of a soft velvet fabric may be perceived as a lush purple, while the touch of a rough surface might evoke a gritty gray.

Touch-color synesthesia might cause complex visual reactions to pain or intimate touch. The quality of the tactile sensation may also inform the brightness and hue of the associated color. For example, a soft touch may evoke a pastel color, while a sharp sensation may evoke a brighter color.

Auditory-tactile synesthesia

Auditory-tactile synesthesia is a form of synesthesia in which sounds or music can elicit tactile sensations or physical touch experiences. When the synesthete hears certain sounds or musical notes, they may experience corresponding sensations on their body or perceptions of touch in specific areas. 

For example, a particular musical note may feel like a gentle brush against the skin, while a louder sound might evoke a sensation of pressure or vibration. The frequency of a sound often informs the sensation in the synesthete’s body. For example, high-frequency sounds tend to produce more widespread tactile sensations and often manifest higher up on the body. 

Emotion-color synesthesia

Emotion-color synesthesia is frequently characterized by the association of specific emotions with distinct colors. Feelings of happiness may be associated with a warm and vibrant yellow, while sadness might evoke a cool and muted blue. 

The type and intensity of the emotion may influence the qualities of the perceived color. For example, an intense negative emotion, like anger, might manifest as a bright red, excitement may evoke a bright or neon color, and fear may be dark. Emotions like love and happiness, on the other hand, might be experienced as soft or pastel colors.

Spatial sequence synesthesia

Spatial sequence synesthesia is a unique type of synesthesia where individuals typically perceive sequences, such as numbers, months, or days of the week, as occupying specific spatial locations. In other words, they may experience a consistent spatial arrangement or pattern for these sequential elements. 

For example, a synesthete might perceive a yearly calendar as being a circular “track” that extends into the distance and comes back around. They may visualize days of the week on a carousel or even see holidays floating over dates in their mind's eye.

Number-form synesthesia

Number-form synesthesia is a type of synesthesia in which individuals may perceive numbers as having specific, distorted spatial forms or arrangements. Whereas a neurotypical mind usually visualizes numbers in a left-right arrangement on a number line, someone with number-form synesthesia might see the numbers scattered around in space or on different planes. 

Studies have found that individuals with number-form synesthesia tend to have greater “visuospatial flexibility,” which generally refers to the cognitive ability to mentally manipulate visual and spatial information.

Ordinal linguistic personification

Ordinal linguistic personification (OLP) is a specific form of synesthesia in which individuals may associate personality traits or characteristics with numbers, letters, days of the week, months, or other ordered sequences. In other words, they usually perceive ordinal entities as having distinct personalities, emotions, or traits. 

For example, the number seven may exist as a small, playful child among other numeric “characters” in the synesthete’s mind. This form of synesthesia often accompanies other forms of synesthesia, and, as with other forms of synesthesia, the associations tend to be consistent over time.

Mirror-touch synesthesia

Mirror-touch synesthesia is a rare form of synesthesia in which individuals may involuntarily experience a physical sensation on their own body when they see or observe someone else being touched. In other words, they may "mirror" the sensations they perceive in others. Research has found that mirror-touch synesthesia sometimes develops after amputation. This type of synesthesia can also be more common in those with autism. 

How common is synesthesia?

Possible causes and theories

The causes of synesthesia are not fully understood by scientists at this time, but several theories have been proposed, and brain scans of synesthetes have often revealed structural differences. One prominent theory suggests that synesthesia may arise from cross-activation between brain areas that are responsible for different senses. Another theory proposes that synesthesia could be the result of enhanced connectivity or communication between brain regions. 

While there may be no single synesthesia gene, genetic factors may play a role, as synesthesia tends to run in families. While these theories can provide insight into the mechanisms behind synesthesia, more research is likely needed to gain a comprehensive understanding of its underlying causes.

Is synesthesia a disorder?

In general, synesthesia is not considered a disorder or a medical condition. Instead, it is often referred to as a neurological phenomenon or a perceptual trait. Synesthetes generally lead normal, productive lives and can find unique ways to harness their synesthetic perceptions.

While some synesthetes may initially find their experiences overwhelming or confusing, many individuals come to appreciate the richness and diversity that synesthesia brings to their perspective of the world. It can be crucial to understand that synesthesia is a valid and natural variation of human perception, and it should be celebrated rather than pathologized.

Still, synesthesia may make certain experiences unpleasant or overwhelming for some people. For example, sound-touch synesthesia may make it difficult to enjoy oneself in loud or noisy environments. 

Some types of synesthesia may correlate with mental health concerns as well. For instance, grapheme-color synesthesia is often associated with post-traumatic stress disorder (PTSD), and children with synesthesia may have higher rates of anxiety. 

Benefits of online therapy

If you are experiencing mental health concerns related to synesthesia or find it difficult to enjoy certain experiences because of your sensory perceptions, it may be worth consulting a mental health professional. Online therapy platforms like BetterHelp can connect you with a therapist who understands what you’re going through. With online therapy, you can attend sessions from the comfort of your own home, which may be beneficial for those prone to sensory overload.

Effectiveness of online therapy 

While synesthesia is not usually categorized as a disorder, it may be linked to other conditions requiring support and treatment. Online therapy can be effective for managing numerous neurodevelopmental disorders, such as ADHD, and treating a variety of other sensory-related conditions. In one comprehensive review, researchers assessed six web-based randomized controlled trials and found that these online interventions were usually “more effective than waiting list in improving attention deficit and social function of adults and children with ADHD.”