Yes! Maybe? Red-orange!
Conventional wisdom says that synesthesia is innate -- you're either born with the condition or you're not, end of story. If you happen not to have been born that way but would really, really love to experience numbers as colors, or colors as sound ... then you, my sense-straight friend, are pretty much out of luck.
Except ... maybe not? A group of psychologists at the University of Amsterdam have been testing whether synesthesia might, actually, be learned. Synesthetes' innate cognitive wiring leads them to augment their perception of the physical world; the researchers wanted to see whether the reverse could take place -- whether an augmented physical world could lead to synesthetic perceptions in people who weren't born with "crossed senses." And the researchers have now published their findings in the journal PLoS One.
Those findings, it should be said, are fairly inconclusive, but they also offer some hope -- some colorful, fragrant hope! -- to the wannabe synesthetes of the world. The Dutch scientists' attempt at synesthesia-in-reverse is the first experiment of its kind, and it might well lead to more research into the intriguing realm of willful sense-crossing.
The team focused on one of the more common types of the condition -- color-graphemic synesthesia -- which leads people to perceive colors when they're reading letters. (So, for example, they'll read the letter "a" as light blue.) They wanted to determine "whether traits typically regarded as markers of synesthesia can be acquired by simply reading in color" -- and "whether reading books with colored letters can make letter-color associations automatic, perceptual in nature, and consistent over time."
So they gathered a group of 17 non-synesthetes and tasked them with reading specially printed books: books with the letters a, e, s, and t printed in colors -- red, orange, green, or blue -- for which the participants had expressed a preference. (The point of that matching was to leverage subjective experience, "the hallmark of synesthesia.") Each participant read, on average, 100,000 words of customized, multi-chromatized text.
What the researchers found, however, was that it seemed to take only around 49,000 words to create a smaller Stroop effect in participants -- that is, after only 49,000 letter-colored words read, participants were able to distinguish between the word "red" and the color red in tests. (In addition, the researchers note, the Stroop effect correlated with subjective responses on a questionnaire that asked participants about the degree to which they actually thought about these letters in color.) Similar effects weren't seen across the tasks the participants were asked to complete -- the crowding task, for example. Overall, though, the researchers' findings suggest that, as a result of their colored-letter exposure, the participants had built up a color-letter association that existed independently of the letters themselves. Pseudo-synesthesia! "The results," they claim, "suggest that reading in color appears to be a promising avenue for training grapheme-color synesthesia."
A "promising avenue"! You can almost smell the excitement.
Via the Wall Street Journal