Can You Make Me See Red?

A common type of synesthesia is "colored-hearing." People with this condition see specific colors in their "mind's eye" when they hear words, letters or numbers spoken out loud. The term "mind's eye" is used because although these people see the colors in front of them, the colors don't interfere with their normal vision. Another common type of synesthesia is "colored-touch." People with this condition see colors when they feel certain objects.

To learn more about synesthesia, Colin Blakemore's team at Oxford University recently studied an interesting subgroup of people with the condition?-people who say that they have been colored-hearing synesthetes all their life, even after becoming blinded by injury or disease to the retina. "We wondered whether they might be just imagining remembered colors rather than having genuine visual sensations, so long after losing their real sight," says Megan Steven, a graduate student at Oxford and the lead author of the study.

Six volunteers with colored-hearing synesthesia who had been blind at least 10 years participated in the study. They were asked to describe the colors they saw when hearing the names of each day of the week, month of the year, letter of the alphabet and/or number from 1-100 (counting by tens after the first 10 digits). Their responses were recorded. Two months after this initial screening, the volunteers were surprised with a second, identical test.

"What we found was an amazing correlation between the two testing days," says Steven. "If a subject said that A was pale green on the first testing day, they would say that the letter was a light or pale green on the surprise testing day two months later. This is strong evidence that they were experiencing a genuine phenomenon?-they actually appeared to be seeing colors in their mind's eye, even though they had been blind for at least 10 years." These findings suggest, she adds, that the visual areas of the brain can still remain active after blindness.

Two of the six volunteers also had a special form of colored-touch that Steven coined "colored-Braille," which caused them to see colors when they read Braille letters. The repeat test showed that their responses to the colors they "touched" as they read were also genuine. Since they learned Braille after they started to become blind, this implies that the connections in their brains leading to the color sensations were established through some kind of learning. Synesthesia runs in families and almost certainly depends on a genetic factor. However the particular form that it takes might depend on individual experience.

In a further experiment, the researchers tried to determine what was driving the synesthesia. For the blind people with colored hearing, the meaning of a word, rather than its sound alone, seems to be important. For example, when the word "March" was used in a sentence to mean a particular month of the year, one volunteer saw a "dark greeny blue" color. But when he heard the same word used as a verb ("The soldiers march across the bridge.") he did not see a color. Interestingly, when the same volunteer, who also has colored-Braille synesthesia, read the number 1, the musical note A, or the letter A in Braille?-all of which are represented by a single dot in the upper-left corner?-he saw the same color (white). His colored-Braille synesthesia appears to depend on the pattern of the dots, not the semantic representation.

In the next step of their research, Steven and her colleagues are using fMRI to investigate which areas of the brain in late-blind synesthetes are activated during colored-hearing and colored-Braille.

I was speaking to those (i.e., Brandon, etc.) that continually ask for that evidence.

Ok, now you are getting a bit desparate I think. It was just an exercise to try to show how something might be hard to do for anyone. Why are you putting meaning to it that is not there?

Ok, now you are getting a bit desparate I think. It was just an exercise to try to show how something might be hard to do for anyone. Why are you putting meaning to it that is not there?