Color plays a vital role in the world in which we live. Color can sway thinking, change actions, and cause reactions. Color, simply stated, is irreplaceable. In the human brain, the five sensory pathways are parallel to one another. However, in some situations, a cross-over from one pathway to the other occurs. One may see the color yellow and feel happy, black and feel sad, white and feel clean. Despite the amount of research done in the field and the widespread acceptance of many of its basic theories, chromology (the study of the psychology of color) is often doubted, seen by critics as a result of cultural conditioning affected by many aspects of the environment. Regardless, it is natural to place associations between colors and emotions. However, associations between colors and senses – sight, sound, smell, touch, or taste – is rare.
Synesthesia is a neurological condition that affects approximately five percent of the population, occurring most often in artists. This causes individuals to cross senses, wherein the stimulation of one sense leads to another cognitive reaction. Below are a few of the most common forms of this condition:
1. Grapheme-Color Synesthesia
Of the 738 self-reported types of synesthesia, grapheme-color is the most common. Grapheme-Color Synesthesia is where an individual sees letters or numbers as a specific color. Usually, these associations vary from person to person, but some letters are more likely to be reported as a certain color. For example, research shows that 'A' is likely to be seen in red in the mind of a Synesthete.
2. Number-Form Synesthesia
Number-Form is another reported type of Synesthesia that is most common in scientists and mathematicians. A number form is essentially a mental map that consists of numbers that are involuntarily visualized when a person with number-form synesthesia thinks about numbers. In the words of a Synesthete, numbers appear as "the most grotesque variety of shapes, which run in all sorts of angles, bends, curves, and zig-zags." Some theories about the cause of number-form synesthesia is that it is a product of "cross-activation" between regions in the parietal lobe – a part of the brain that is involved in numerical and spatial cognition. This would partially explain the 3D visualization of number maps, though this form of Synesthesia continues to stump even those who research it extensively.
3. Ordinal-Linguistic Synesthesia.
One may be familiar with personification in a literary sense, where authors "attribute a personal nature or human characteristics to something nonhuman", but perhaps not in a synesthetic sense. Those with Ordinal-Linguistic Personification (OLP) associate ordered sequences, such as numbers, days, months and letters, with personalities and genders. The wife of Jesse Jaren, a Seattle-based artist, has OLP with every letter of the alphabet. Her husband illustrated her visions, using her descriptions. For example, according to her, 'Z' is a short, large, red-headed man who wears black. He is "distracted by his own ideas, an unlikely leader, and does what he wants most of the time." Jaren created illustrations of these characters from his wife's descriptions.
4. Lexical-Gustatory Synesthesia
Lexical-Gustatory Synesthesia, because it is so rare, has not been researched extensively. Those with a form of synesthesia evoke different kinds of tastes when they hear certain words or phonemes. According to research, these tastes could be attributed to what the synesthete ate often early in life.
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