Synesthesia: The Medical Condition of Associating Letters and Numbers With Certain Colors

Synesthesia is a rare condition. The type most common form is called Grapheme-Color Synesthesia. With this type of Synesthesia, people with the condition associate certain colors with certain letters or numbers.(Motluk, 2004) In some cases, even words have their own color. The color associations always stay the same, even when the participants are tested years later. Some examples would be red associated with the letter F, or green associated with the number 1. When Synesthetics see a word that is written in black ink it will appear colorful.

Many of the people who have this disorder are left-handed and women (Motluk, 1994.) The female to male ratio is 6:1. This information was the result of two studies conducted within the population.(Baron-Cohen, 1996) People who are diagnosed with Synesthesia are usually tested many times throughout their lifetime. Throughout these tests, the associations between letters, words, or numbers and colors always stay the same.(Motluk, 2004) The reasons for the ties between the digits and the colors are unknown. Although, it may have some kind of connection with sequences such as the ABC's or 123's.

There are several screening techniques that are used in diagnosing and confirming Synesthesia.(Crane, 2006) These are called pop-out, segregation, cross-modality imagery, and the Stroop test. The Stroop test may be the most popular. In this test, different words are shown in different colors. The time in which it takes the participant to answer which color it is written in, is recorded. True Synesthetics will take longer answering than non-Synesthetics. The color of their associations, and the actual color of the word gets confused. Also, when asked 24 hours later the color of each word, the true Synesthetics could not remember whereas most of the non-Synesthetics could remember.

Optometrists can diagnose this condition, as well as prescribe vision therapy to their clients who have this condition.(Groffman, 1999) This condition is more noticeable in children.

In Grapheme-Color Synesthesia, during auditory testing, the brightness of the colors associated with graphemes depended on the pitch of the particular grapheme that was being spoken. If the digit was spoken in a high pitch, the testee would see it in a brighter color. Also, the size depended on the volume of which it was spoken. So, the louder the word was spoken, the bigger it would appear. It is possible that this could be due to the pronunciation of the vowels in words.(Marks, 1975)

In Grapheme-Color Synesthesia, hearing or seeing colors do not provoke any letter, number, or word images. So, in other words, the associations occurred after seeing or hearing digits, not the other way around. If someone sees colors from words, it is a different type of Synesthesia, called Chromatic-Lexical Synesthesia.(Baron-Cohen, 1987) This type is more rare than Grapheme-Color Synesthesia.

One theory suggests that, people who have Synesthesia just retain color memories from childhood. An example would be colorful alphabetical or numerical magnets that the child had played with. This theory, however, does not explain all aspects of the condition.(Ramachandran, 2005)

Research was conducted on adults and suggests that, for females, one in every 1,150 have Synesthesia. And for males, it is one in every 7,150.(Rich, 2005) . A new theory suggests that males who are born with this disorder usually die as children. This could explain why more females have the disorder.(Freeman, 2002)

Research has also shown that dyslexia, ADD, and autism run in the families of people who have Synesthesia. Emotional instability is very likely to run in the families as well. It is estimated that one third of the families of Synesthetics have this condition within them. A study was conducted, which consisted of six families. Results show that all of the six that were tested did have Synesthesia within them.(Baron-Cohen, 1996)

It is believed that one gene which is responsible for causing Synesthesia gets passed from one generation to the next by the X chromosome, as a Dominant trait.(Smilek, 2005) This could explain why Synesthesia runs in families.

One theory suggests that, crossed wires in the brain cause Synesthesia. These crossing can occur in different areas of the brain depending on which type of Synesthesia is present. This could mean that Synesthesia is a genetic mutation.(Ramachandran, 2001) If, by some chance, the causes of this condition are not genetic but brain-related, than everyone has an equal chance of experiencing this phenomenon.(Motluk, 2004)

One of the earliest records of this condition is from the late 1600's. These records show a documented case within a family in Greece.(Groffman, 1999)

The days of the week had associations with colors in many testees. Again, this could have something to do with sequences. The colors that are associated with certain letters or numbers are the same in many Synesthetics, such as the letter D is brown for 57% of the Synesthetics who were tested.(Rich, 2005)

A new theory states that the emotional part of the brain controls senses.(Motluk, 1994) This is the same area of the brain that processes information. This could explain why mostly women have the condition. This theory, however goes against previous theories pertaining to these particular brain functions.

A study of 150 Synesthetics found that they all were artistic in some way. They also have very good verbal-reasoning skills, on the down side they have sensitivity to lights and sounds with frequent migraines. Pseudosynesthesia can occur, usually with drug use.(Groffman, 1999) This is when people do not actually have the condition, but will experience symptoms.

Testing was done on one individual, with Grapheme-Color Synesthesia; results found that literally showing graphemes to the testee was not needed for the association with a specific color to occur.(Dixon, 2000) During these tests, the letters, numbers, or words that were shown were presented in black ink. The associations were made just be hearing that specific grapheme. Results were always consistent.

Three studies were conducted to figure the possibility for this condition to be sex-linked. In all three, tests were given to diagnose all participants. In the first two, the testing given indicated that 1 in every 2000 people have this condition.(Baron-Cohen, 1996) One-third of those participants stated that it occurs within their family. In the third study, tests given to the family members did confirm that this condition is inheritable.

Discussion

A 21-year-old was tested with seven non-Synesthetic participants to see if her color experiences help to memorize digits. Three tests were given to her, one with black digits, one with digit's the same colors as she associated with them, and in the last: the digits were different colors than the colors she associated with them. In the last test given to her, where the colors were different than her associations, she did very poor on memorizing them, unlike the other two tests.(Smilek, 2002) Even 48 hours later, she did well at recalling the digits, whereas the other seven participants, who were non-Synesthetics, did not. Results did confirm that her associations help her memorizing skills greatly.(Smilek, 2002)

Another recent study shows that Synesthesia may not be X-linked. A set of male twins who were 10-years-old were tested for Grapheme-Color Synesthesia. The test confirmed that only one of the twins has this condition. Since, the boys are identical twins, it was concluded that Synesthesia couldn't be an X-linked Dominant trait.(Smilek, 2005)

A musician has one of the most rare forms of Synesthesia, which when hearing a specific note or pitch, she gets a specific taste or flavor in her mouth. In another documented case, the individual could actually taste an entire meal while hearing specific musical notes.(Geeli, 2005) This individual had no prior musical training, but perhaps with some training she could lessen her associations to only one specific flavor.

It is possible that, people don't even realize that they have the disorder. They think that these associations are normal, until they find out that not everyone makes these types of associations between digits and colors, or sounds and tastes. Another possibility for there being more females than males with this disorder, is that males do not report their symptoms.(Ward, 2005)

A neuroscientist in California believes that a study currently being conducted on people who can see auras may actually help to understand Synesthesia.(Holden, 2004) Perhaps, seeing auras and Synesthesia are one in the same.

A 76-year-old woman was tested for and confirmed to have Chromatic-Lexical Synesthesia.(Baron-Cohen, 1987) The testing method used was cross-modality imagery. As with Grapheme-Color Synesthesia, she also associated colors with letters or numbers, but her associations were stronger with words. Results found that the colors she associated with words had nothing to do with that particular words meaning. Random letters were put together in the form of words. Their colors were determined by the letters.

References

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