I Hear Red. I Taste 5.
In this Synesthesia Guide:
- Introduction to Synesthesia
- 5 Criteria of Synesthesia
- Synesthesia and Genetics
Scientists have identified at least forty different kinds of synesthesia.
The types are named by the actual sense stimulated first, then by the sense that reacts. A person who hears color is a visual auditory synesthete, while one who sees color when hearing a particular sound is experiencing auditory vision. Synesthesia is a rare condition, though it's difficult to know exactly how uncommon it is. Some estimates put it at 1 in 25,000 people. Other reports suggest that it may be as high as 15% of the population. Part of the reason that the exact incidence is so difficult to pinpoint is that many synesthetes don't realize that their way of seeing things is unique. Others may fear that they'll be considered crazy if they try to explain that yellow M&Ms are 5 and red ones are 2.
If It's All In the Genes, Why Don't Twins Have It?
One of the more common types of synesthesia is a correlation between letters or digits and color. Colored-letter synesthesia is also one of the more researched types of synesthesia. In one experiment, researchers tested a pair of twins, only one of whom exhibited synesthesia. The twins were identical 11 year old girls, identified only as EB and JB. EB is a colored-digit synesthete, experiencing color when she sees numbers. The researchers began by ascertaining what color-digit correlations EB experienced through having her name the color she experienced when viewing a digit on a computer monitor, then adjusting the color of the digit on the screen until it matched her perception of the color. The test was repeated five times for each digit in random order, and EB's identification of color with digit was 100% consistent.
The actual test used to determine if EB is a true synesthete is called a Stroop test. In the Stroop test, both girls were shown a series of digits on the computer screen and asked to name the number as quickly as they could. Some of the digits corresponded in color to the way that EB sees numbers. Others were colored differently. In theory, JB, who does not associate colors and numbers, should name all the numbers easily. EB, who would have to overcome her initial perception of the digit, should identify the numbers that were the 'wrong' color much more slowly than the others. In fact, EB consistently took nearly ten percent longer to identify the numbers that didn't match her color perception as it did for her to identify those that did. JB showed no significant differences in time.
Why one twin and not the other? Researchers suspect that synesthesia is a gender-linked trait transmitted by a dominant X gene.
Is The Blue That You See the Five That I Hear?
So if five is red, does that mean that all synesthetes experience the number 5 as red?
According to researchers, the answer to that is a qualified no. While synesthetes are completely consistent in identifying the same number or letter with the same color over trials separated by as much as a year, their associations are not consistent with each other. One may see the letter U as bright yellow, while another experiences it as dull gray.
As more and more research is being done, however, some interesting trends are emerging. The number one, for instance, is often a shade of red, and the number 5 tends to be in the blue range.