27 January 2013
Synesthesia traced to childhood toy
by Will Parker
Experiencing a color when viewing particular letters or numbers - known as color-grapheme synesthesia - may partly be a learned behavior, say Stanford researchers who uncovered startlingly similar color-letter pairings shared by a number of color grapheme synesthetes who played with the same childhood toy.
Researchers Nathan Witthoft and Jonathan Winawer based their findings, appearing in Psychological Science, on work with 11 color grapheme synesthetes.
Witthoft said that matching data from the 11 participants showed reliably consistent letter-color matches, both within and between testing sessions (even after a delay of up to 7 years). The participants also performed a timed task, in which they were presented with colored letters for 1 second each and required to indicate whether the color was consistent with their synesthetic association. Their data show that they were able to perform the task rapidly and accurately.
Witthoft and Winawer say that these data suggest that the participants' color-letter associations are specific, automatic, and relatively constant over time, thereby meeting the criteria for true synesthesia.
"The degree of similarity in the letter-color pairings across participants, along with the regular repeating pattern in the colors found in each individual's letter-color pairings, indicates that the pairings were learned from the magnetic colored letters that the participants had been exposed to in childhood," explained Witthoft.
The paper claims that these are the first and only data to show learned synesthesia of this kind in more than a single individual. Witthoft stresses this does not mean that exposure to the colored letter magnets was sufficient to induce synesthesia in the participants, though it may have increased the chances.
Based on their findings, Witthoft and Winawer conclude that a complete explanation of synesthesia must incorporate a central role for learning and memory.
Source: Psychological Science