Synesthesia is the simultaneous perception of different senses. There are three different types of synesthesia: sensory, cognitive and emotional. Sensory synesthesia occurs when one of the senses (e.g., sight) is perceived together with another sense (e.g., smell). So when one sees the color blue, one may smell the sea, for example. Cognitive synesthesia occurs when something that is learned is perceived together with a sense. For example, when one hears or reads a particular word, such as “beyond,” one may associate it with a particular mental image (e.g., of a forest or the sea). Emotional synesthesia occurs when one feels a particular emotion in association with a color, letter, shape or number. The number eight, or the color red, for example, may evoke a sense of anger.
Synesthesia is not due to a hallucination or the imagination. It is very real. It is due to enhanced connections between neurons that are responsible for perceiving different senses. Synesthesia is thought to occur in one out of every 2,000 individuals. It is more common in women. People who experience synesthesia tend to often confuse right and left. They have a poor sense of direction but a very good memory and are often perfectionists. These people are often introverted but very creative and talented in the arts.
There are many different forms of synesthesia, since there are five different senses, and a combination of the senses can produce many different types of perceptions.
Grapheme-color synesthesia
This is one of the more common forms of synesthesia. In this form of synesthesia, the individual associates a particular letter or number with a specific color. For example, the letter A may be associated with red, the letter B with blue and so on.
Sound-color synesthesia
This is another more common form of synesthesia, where certain sounds trigger the visualization of certain colors and shapes. Often the particular color is also associated with a shape. For example, the color red is associated with a circle, blue with a triangle and so on.
Number form synesthesia
A number form is a mental map of numbers. When the individual thinks of a number, he or she will see a number map. This is likely due to the overlapping of neurons involved number cognition and spatial cognition.
Ordinal-linguistic personification
In this interesting form of synesthesia, numbers and letters are associated with different personalities. For example, the letter A may be associated with rudeness, and the person thinks that A is a rude letter.
Lexical-gustatory synesthesia
This is a rare form of synesthesia, where certain words are associated with certain kinds of tastes. For example, the word “delight” may produce the taste of chocolate ice cream, or the word “finally” may produce the taste of cheesecake.
