Synesthesia refers to a state of being in which an individual’s sensory or cognitive pathways cross with one another. When one pathway gets stimulated, involuntary stimulation of another pathway occurs. This may manifest as tasting colors, seeing sounds, numbers being certain shapes, etc. In other words, synesthesia is simply when you experience one of your senses through another sense.
The word “synesthesia” is derived from the Greek words “synth”, meaning “together” and “ethesia”, meaning “perception.” As such, it means to “perceive together”, which is exactly what occurs for people with synesthesia. People who experience synesthesia are also referred to as synesthetes.
Many synesthetes, myself included, consider synesthesia to be more beneficial than detrimental. However, synesthesia can sometimes have its drawbacks, as certain experiences can be startling (particularly in the case of new synesthesia experiences) and it can be distracting or confusing at times, such as when reading or performing other tasks. This can be especially true in childhood, or when learning tasks for the first time.
Synesthesia is not a mental illness and isn’t harmful. Rather, it’s a unique means of experiencing the world through the intermingling of senses. It has been asserted that synesthetes may perform at greater levels on memory tests than non-synesthetes. Synesthetes also often have the ability to produce enhanced mental imagery and have a greater propensity towards creative thinking and problem solving than non-synesthetes. Some have asserted that this is due to greater connectivity in certain areas of the brain.
Since synesthesia can involve any of the senses, it’s estimated that there may be as many as anywhere from sixty to eighty subtypes. Some of the more widely known manifestations of synesthesia include auditory-tactile, chromesthesia, grapheme-color, lexical-gustatory, mirror-touch, number form, ordinal linguistic personification, and spatial sequence synesthesia.
Auditory-tactile synesthesia is when a sound results in a bodily sensation. Chromesthesia results in colors being triggered by sounds, grapheme-color synesthesia is when colors and numbers are associated with certain colors, and lexical-gustatory synesthesia occurs when words trigger specific tastes. Mirror-touch synesthesia can be likened to an intensified sense of empathy, whereby a person feels as though they’re physically being touched if they witness someone else being touched or being physically impacted in some way. Number form synesthesia occurs when a mental string of numbers appears when someone thinks of them and ordinal linguistic personification is when ordinal sequences (such as the days of the week) are correlated with genders or personalities. Spatial sequence synesthesia occurs when an individual sees numerical sequences at various points in space (either up close or far away).
Many synesthetes experience more than one type of synesthesia, with the most common types being grapheme-color synesthesia and chromesthesia.
It’s estimated that approximately 3-5% of the population has some form of synesthesia. This number is difficult to determine, for a variety of reasons. Many people don’t discuss their synesthesia-related experiences, because either they think others won’t understand, or because they think everyone has similar experiences and they don’t realize it’s a unique way of being.
Synesthesia is often first noticed during early childhood, though it’s possible for synesthesia to develop later in life, either temporarily as the result of meditation, sensory deprivation, or psychedelics, or more permanently, as the result of strokes, brain tumors, or head trauma. Synesthesia does seem to have a genetic component, but it is not fully understood.
Some researchers even postulate that everyone is born with some level of synesthesia, but the neural connections are pruned in most people as they grow, decreasing synesthesia-like experiences.
Someone might be a synesthete if they experience associations between two or more senses. There are no clinical guidelines for diagnosing synesthesia, but there are different types of synesthesia tests, with many of them being in a test-retest format, to gauge consistency.
Consistency across multiple tests can help to determine whether someone is genuinely experiencing synesthesia or not. This is because consistency is a major sign of being a synesthete. For example, if a synesthete experiences the letter ‘D’ as being green, the note ‘C#’ as being in the shape of a triangle, or the color orange evoking a particular texture, they will be consistent in those experiences months or years later. Conversely, if someone is not a synesthete, their reported experiences may shift over time.