If someone were to ask you the color of your name, would you be able to answer? For some people, the answer might be obvious, but for the majority of the population, there won’t be a real answer. It would be the same if someone asked the taste of purple or the personality of the letter A. While most people would think the asker was looking for something poetic or simply making a joke, a select few would find that they had real and tangible experiences to share.

The Basics

According to Cleveland Clinic, synesthesia is phenomenon where a person experiences sensory crossover, where one sense triggers another. Basically, a synesthete, or person with synesthesia, will experience extra sensory stimulation in response to a specific trigger.

Some of the most common types of synesthesia include grapheme-color synesthesia and chromesthesia. Grapheme-color synesthesia is where the person associates letters and numbers with colors, even if they are written in a different color. Each person’s perception of the relationship between symbols and colors is unique.

Like all other types of synesthesia, these connections are involuntary, which separates this sense from simple association. Many people can have associations with different colors and symbols, but this may change due to different experiences or contexts. However, a synesthete will remain consistent in their connections, despite any length of time. A test that is often given to grapheme-color synesthetes is to have them list all of their connections so that someone else can record them. After an unspecified amount of time, the synesthete is asked again. Their answers will most likely be extremely consistent with the earlier recorded observations, showing that their perception is not affected by whims or time.

Another common type of synesthesia is chromesthesia, where sound causes some sort of visual sensation such as shapes, colors, or movement. This type of synesthesia can be sorted into two categories. First, there are associator synesthetes, who see the visuals in their mind’s eye or get a strong mental impression, even if they are not actually seeing it in front of them. According to the Synesthesia Tree , this form of synesthesia makes up 90% of auditory-visual synesthetes. The other 10% are known as projector synesthetes. They actually will see the shapes, colors, or movements as part of their external environment in response to sound. Some auditory-visual synesthetes may experience both types, and there is a huge range within these categories as well. Different types of sounds such as individual pitches, timbres, or voices can serve as the trigger, while there can also be a variety of resulting sensations such as position and texture. This type of synesthesia is common in those involved in the arts, especially visual arts, as this perception can serve as inspiration for visual pieces based off of music. Some also “reverse engineer” their visuals to make music. Like all types of synesthesia, there is a huge range of varieties within this type.

What Causes the Connections?

Synesthesia is widely accepted as being caused by increased neural connections in the brain, especially between the two senses being linked. Synesthesia is often genetic, but the children of a synesthete will not necessarily inherit the same type nor same perceptions. Synesthesia has also been documented to have begun in response to head injuries or while under the influence of drugs, both of which point to synesthesia having very much to do with how our brains function.

With so many variations and a wide range of differing perceptions of the world, synesthesia is an amazing and fascinating phenomenon that has impacted our world, even for the majority who do not experience the connections. This unique way of perceiving the world provides more angles through which to observe our lives, helping us understand our senses in novel ways.