Is the letter J a shade of tangerine or is it more grassy green?

New research suggests that the 1-2% of the population with an unusual condition that causes the brain to see letters and numbers in a rainbow of colors don’t have an inborn sixth sense; they develop their character-color associations over time.

Synesthesia is a neurological phenomenon in which experiencing one sense leads to an automatic, involuntary experience in another. For example, there are people who taste sounds and people who see music. The condition runs in families, although the exact gene or genes involved have yet to be discovered.

Those with grapheme synesthesia experience individual letters or numbers as having unique colors associated with them. “A is yellow, that’s what A is…it doesn’t ever change,” said Kaleigh Brady, a grapheme synesthete (a person with synesthesia) from California. These colors are individual to the person; though Brady sees yellow another synesthete might see A as blue or red.

“Slipper is most beautiful word. It’s kind of purple with a vibrant turquoise color in the middle.”

Synesthesia has been systematically described for over 200 years, but how the condition initially presents itself during childhood has remained an open question.

Now, a study published in November in the journal Frontiers in Human Neuroscience suggests an answer. Julia Simner and Angela Bain, researchers at the University of Edinburgh, tested 80 synesthetic children over the course of three years to document the colors they saw when presented with the Latin alphabet and numbers 0-9. A preliminary paper from 2009 showed data from the first year of the study.

Kathleen Akins, a synesthesia researcher at the Simon Frasier University in British Columbia, said, “I have been waiting, literally, for two years to see the results….we were all holding our breath to see what would happen.”

Simner and Bain found that from the time they were 6 or 7 years old until they were 10 or 11, the synesthetes accumulated a growing number of specific color associations. The character-color linkages were not automatically sparked because of hard wiring, they were learned over time.

“A lot of people are surprised at how slowly it develops,” said Marcus Watson, a synesthesia researcher unaffiliated with the study. They now know, “At age 13 most [synesthetic] kids don’t have consistent numbers or letters. Most people thought colors would be in place by the time the kids were kindergarten age,” said Watson.

Brady agreed with the study’s findings. “I first noticed it when I was 6 or so. It was definitely more prominent as I got older.”

The findings may have implications beyond the study of synesthesia itself. Synesthetes have been shown to excel in areas enhanced by their unique perception. Those with grapheme synesthesia are at ease with complex letters and numbers in areas such as mathematics or writing. Richard Feynman, 1965 Physics Nobel Prize winner, described seeing equations “with light-tan j’s, slightly violet-bluish n’s, and dark brown x’s flying around.” Vladimir Nobokov was another noted grapheme synesthete.

Brady, who is finishing a degree in journalism, says her synesthesia gives her an advantage memorizing vocabulary and spelling by visualizing the color patterns. For example conscious “is red and purple and white. Dark purple, bluish purple,” she said.

Now, building on Simner and Bain’s findings, colorful text may not be relegated to elementary classrooms. Adding rainbow hues to vocabulary lessons in middle school may help kids better retain the information.

Color associations gleaned from synesthetes may even have a place in adult English as a Second Language classes.

“They used to talk about [synesthesia] being very unusual from what normal people can do, but there’s now a consensus that that’s not quite right,” said Watson. He explained synesthetes should actually be thought of as an extreme end of a spectrum. “In that way these [studies] tell us about synesthetes but also the population as a whole.”