Synesthesia
Synesthesia comes in many different forms, with almost 60 known possible combinations (Day, 2013). However, some forms are much more common than others. This page will cover in-depth the five most common types of synesthesia: colored letters, colored hearing, spatial sequence, taste/smell synesthesia, and auras and orgasms (going from most common to least common).
1. Grapheme -> Color Synesthesia
If you look at the image on the left and think to yourself, "hey! those colors are all wrong!", you probably have grapheme-color synesthesia. A grapheme is the smallest written unit of a spoken language, including alphabetic letters, numbers, punctuation marks, etc. ("grapheme", 2001), which is why this form of synesthesia's more common name is "colored letters". Grapheme-color synesthesia is the most common form of synesthesia, with an estimation of 1 in 42 people having this form (Day, 2013).
When a synesthete with grapheme-color synesthesia sees a letter printed in black ink, such as 9 they experience their "colored letters" one of two ways, either the color associated with the color appears to them internally (in the mind's eye) or the color has a specific location (such as layered over the letter's original black ink). The color will appear if the grapheme is read, heard or thought of. (Cytowic & Eagleman, 2009).
2. Audio -> Color Synesthesia
The common name for audio-color synesthesia is "colored hearing". For about 40% of synesthetes, colors are triggered by a range of sounds, including cat meows, voices, doors slamming, and especially music (Day, 2013). The experience of colored hearing can be difficult for synesthetes to explain, but many liken the experience to that of fireworks: where bursts of colored shapes appear in the visual field only to fade away when the sound stimulus stops. However, some synesthetes only have colored hearing with some sounds and not others. For example, some only respond to general, everyday sounds while others respond only to music (Cytowic & Eagleman, 2009).
3. Sequence -> Location Synesthesia
Sequence-location synesthesia is more commonly known as "number forms" or "spatial sequence synesthesia". For people with number forms synesthesia, February or Thursday may occupy a precise location in space. That is, numbers, time units, and other concepts are located in space relative to the synesthetes body (Cytowic & Eagleman, 2009).
Types of Synesthesia
4. Taste/Smell Synesthesia
Taste and smell are so connected that it is sometimes hard to distinguish them. What many people think of as taste is actually credited to smell! Smell and taste combine to create flavor. This is why when you have a cold, food loses its flavor due to the lack of ability to smell.
So do synesthetes taste or smell in response to stimuli? Or do they see colors and shapes when they taste or smell? They do both! Sometimes stimuli will produce an aroma or flavor that the synesthete can actually smell or taste. But more commonly, they can see colors or shapes in response to tasting or smelling stimuli. Michael Watson, who inspired the book The Man Who Tasted Shapes, often cooks by altering flavors in order to make his meal "rounder" or give it more "sharp points". For Sean Day, a synesthete researcher, he enjoys eating foods that "taste blue", like milk, cheese, citrus fruits, vanilla, beef, buffalo, and chicken. He sometimes creates crazy concoctions in order to make an entire meal blue, such as baked chicken topped with vanilla ice cream and orange juice concentrate (Cytowic & Eagleman, 2009).
5. Auras & Orgasms
Auras:
Aura synesthesia is very rare. A synesthete with aura synesthesia will perceive colored outlines or auras around people, animals or even inanimate objects.
Although perceiving auras has been portrayed in the media as a psychic ability to read people and their emotions, aura synesthesia is not. However, aura synesthesia is tied to emotion in a different way. Instead of the objects emotion being important, the focus is on the synesthete and how he or she feels about the object. Emotional meaningfulness and familiarity to the perceiver determine whether or not a synesthetic aura appears, with varying intensity depending on how foreign the object or person is (Cytowic & Eagleman, 2009).
Auras can be solid colors, but have been found to be striped, dotted, or even textured. They can be translucent or "washed out" or can be more opaque, sometimes blocking out the original object (Cytowic & Eagleman, 2009).
However, when graphemes are combined to form words, the colors of the graphemes sometimes change. Depending on the context, the colors can change dramatically or slightly. For some synesthetes, the first letter of the word's coloring determines the entire word color and for others all of the letters blend together, creating a muddy mix off all the letter colors in the sequence. Spelling, pronunciation, and word meaning can all influence word color as well. For example, the words DESSERT and DESERT, sound and are spelled similarly, but the pronunciation and meaning of the words can cause them to have drastically different colors (Cytowic & Eagleman, 2009).
​The top word is the word "synaesthesia" (britsh spelling of the word) with each letter written in its' individual color. The bottom word is the word "synaesthesia" when perceived as a whole. This is an example of one letter (in this case, S) influencing the color of the entire word (Cytowic & Eagleman, 2009).
A synesthetic experience of a word before (top) and after (bottom) learning that the word "pythalocyanine" refers to a blue-green pigment. This is an example of meaning influencing the color of a specific word (Cytowic & Eagleman, 2009).
More common than having colored graphemes, however, is to have colors for weekdays and months (pictured middle above). Many people experience weekday-color synesthesia without having any other form of synesthesia. For example, instead of being influenced by a word's letter colors, someone with month-color synesthesia might tell you that August just feels amethyst (Cytowic & Eagleman, 2009).
It is very common for people with grapheme-color synesthesia to experience other attributes applied to their numbers and letters, including location, personality, gender, size, shape, etc. (Cytowic & Eagleman, 2009).
A more specified form of colored hearing is phoneme-color synesthesia, where 10% of synesthetes' colors are triggered by acoustic properties of speech, or the basic linguistic units of speech. For example, the letter e will evoke a different color depending on how it is stressed in a word. This form of synesthesia is frequently confused for grapheme-color synesthesia, because when asked about the color of certain words, both types of synesthetes will respond in similar manners. The main difference between the two is that phoneme-color synesthetes are sensitive to homographs (words spelled the same but pronounced differently) and they see their colors in response to how a word sounds vs. how a word is spelled or its meaning (Cytowic & Eagleman, 2009).
For Jane Bowerman, a colored hearing synesthete interviewed by Cytowic & Eagleman, "the whoosh of a furnace ignition produced a stack of colored lines like a heap of pancakes viewed from the side (left), crickets make shimmering maroon circles that ripple out from the center then fade away, and the sound of her doorbell looks like gray and brown triangles moving off to the right" (2001).
The number forms are typically viewed panoramically, meaning the synesthete has the ability to zoom in and out or move the form around in order to change viewing perspective. Most of the time, number forms are colorless, but for some synesthetes, the forms can be accompanied by shape, texture, color or illumination (Cytowic & Eagleman, 2009).
The most common type of sequence-location synesthesia is having a form for days of the week. Other forms include months of the year, counting integers, years by decade, shoe and clothing sizes, ages, historical eras, time, temperature, etc. (Cytowic & Eagleman, 2009).
Describing their number form synesthesia can be difficult for some synesthetes. In Cytowic and Eagleman's book Wednesday is Indigo Blue (2009), they interviewed some people with sequence-location synesthesia and had them best describe their experiences:
"[The days of the week are] rectangular blocks, upright in a row like dominoes angled about 25 degrees. I see them to my right in peripheral inner vision. Each month has a shape and a color, and these like on an oval . . . . Starting with January at the bottom, they are arranged counterclockwise so that February (light green) is to the immediate right of January while December (royal blue) is to its left." - Marcia Smilack (pg. 110)
"For a single hour I see a close up of that hour like a regular clock, only with a "2" in place of the "12," etc., or the minutes, "20" in place of the 4 . . . Again, I see time as space. Digital clocks drive me crazy!" - Marti Pike (pg. 113)
"A decade is a three-dimensional rectangle in bluish-gray like the uniforms worn in the Civil War. It is shallow. . . [and] suspended in space in front of me slightly to my left in a horizontal position. . . . It is situated right in front of Chicago. I know that sounds funny, but it is true and this is how it works. The spatial plane on which a decade is suspended is a transparent plane; that is why I can see geography behind it." -Marcia Smilack (pg. 115)
"I see the numbers as though I were below and to the left of 6. Starting with 1, the day spirals upward to 12, that is from 12 midnight to 12 noon above it and upward to 12 midnight again. For 12 to 6 or 7 a.m., it is gray-black, from 6 on it gets lighter until at noon its blindingly bright (yellow-white), then gets darker between 5 and 7 p.m. Eight o'clock to ten is a soft blue, and from ten on is dark blue." - Marti Pike (pg. 112)
"[Eras] are arranged in a descending chronological order that reaches back beyond where I can see; after around the fourteenth century, they become so small they are hard to identify. . ." - Marcia Smilack (pg. 119)
All variations of this type of synesthesia can be combined in many different ways, with other aspects as well, such as personality, gender, location or even physical feeling (Cytowic & Eagleman, 2009).
"I remember at age 2 my father was on a ladder painting the left side the wall. I remember to this day thinking why the paint was white, when it smelled blue. . ." (Cytowic & Eagleman, 2009).
Synesthetic Orgasms:
This type of synesthesia has only been found to occur in women (Ward, 2008). Orgasms can cause color, shape, texture, movement or taste for some synesthetes. Many orgasms are described as being accompanied by flashes of colored light, brightly colored shapes moving across a black background, or three-dimensional swirls. Just like synesthetic auras, the key to having a synesthetic experience during orgasm is emotion. For some more sensitive synesthetes, kissing can trigger an experience (Cytowic & Eagleman, 2009).
For Michael Watson, flavor caused the tactile perception of weight, shape, texture and temperature (Cytowic, 2002).
Taste and smell synesthesia are complicated forms of synesthesia. The combinations are widely ranged for synesthetes with this form. The combinations include:
smell - > color / shape touch - > smell / taste
taste - > color / shape phonemes - > taste / smell
sound - > smell / taste words - > taste
color - > smell / taste
