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The Colors of the Alphabet

Imagine that you could taste sounds.  If you were lucky, your name would be delicious—every time someone said it you might taste that one fruit smoothie you love or a fresh-baked cookie.  Each word would be like sampling a new flavor, for better or worse.  This is a form of synesthesia, a condition in which one sense activates a separate sense.  Color-grapheme synesthesia seems more believable to most people.  Due to this condition, about 5% of the world’s population sees numbers and letters as inherently colored, even if they are printed in black.  This can actually improve performance on some tasks, such as a visual search.  The left half of the picture below shows the vision of a normal individual; the right half shows that of an individual with synesthesia.  As you can see, it is much easier to find the 2’s for an individual with synesthesia.

Screen Shot 2013-05-13 at 10.51.32 PM

Though it may seem surprising, those of us without synesthesia experience its effects on a far smaller scale.  For example, if you had to choose either white or black to represent the letter “O,” which would you choose?  How about for the letter “Z?”  If you answered white for “O” and black for “Z,” you are displaying a common association prevalent in both people with synesthesia and for those without.  The factors driving these associations seem to be both learned and naturally occurring, though it is the topic of popular research.  It illuminates the nature of learning and that initially we associate shapes with colors, but as shapes take on meaning the associations change.

Ferrinne Spector and Daphne Maurer of McMaster University studied naturally biased associations between shape and color such as these (“Z” is associated with black and “O” with white) through a series of six experiments.  Prior research had sparked their interest:  they knew wanted to examine similar associations between color-grapheme individuals and individuals with normally functioning senses with a hunch that the two groups were not as different as previously thought.  Brain imaging techniques had found that activation in areas in the parietal lobe used for perception were similar in individuals with synesthesia and also those with typically functioning perception.

They tested toddlers, young adults, and older adults in their experiments that essentially asked participants to associate colors with letters.  This could be problematic with toddlers, who are for the most part illiterate, but Spector and Maurer devised a clever method to determine color-letter associations.  Toddlers were shown a picture of a letter and asked to choose between a series of differently colored boxes that could contain the letter.  The color of the box that they chose for each letter indicated that they associated the box color with the letter.  A picture of the letter was shown, rather than just verbally saying the letter, because the experimenters found no consistent associations without an image of the letter.

By testing such a wide span of ages, they found that all age groups consistently paired “O” with white and “X” with black, deeming it naturally biased.  Young adults and older adults showed chromatic associations between colors and letters that toddlers did not, indicating that these associations were learned.  The only exception to this was that all age groups matched “C” with yellow.  Toddlers did not associate other letters, such as “G” with a consistent color, whereas young adults and older adults paired “G” with green because, of course, the word “green” starts with “g.”  This pairing came readily to older people, whereas toddlers, without this learning, randomly assigned “G” to a color.  Spector and Maurer used data from other experiments to determine that these chromatic associations where shared with individuals with synesthesia.  Later variations of their experiment showed that all test groups paired angular shapes with black and circular shapes with white, much like “Z” being paired to black and “O” to white.

So, what does this all mean?  Spector and Maurer tentatively concluded that some associations were learned (“G” is green), whereas others are naturally occurring (“O” is white).  These intrinsic associations could be due to shapes seen in nature.  Jagged objects have more shadows and could be darker and more easily associated with black; the opposite is true for rounded objects.  These experiences could alter connections in the brain to establish associations as the individual aged.  Whatever associations in the brain are being made, synesthesia was presumed to amp those associations up a notch to the extent that letters appeared with their own distinct colors.  Spector and Maurer proposed that further experiments could test individuals from different cultures and languages, who may not initially associate “G” with green because they do no speak English.  These results would generate evidence that differentiated between intrinsic and learned associations.  Spector and Maurer’s research shows that even though synesthesia sounds like an abstract and perhaps unbelievable condition, everyone demonstrates some synesthesia-like tendencies, even if you do not perceive these letters as brightly colored.



Ferrinne, S., Maurer, D.  (2011). The colors of the alphabet: Naturally-biased associations between shape and color. Journal of Experimental Psychology: Human Perception and Performance, 37(2), Apr 2011, 484-495. doi: 10.1037/a0021437



Macalester University.  Grapheme-color synesthesia. Retrieved from



  1. May 17th, 2013 at 19:59 | #1

    This study is really fascinating. I’ve always thought synesthesia is an interesting topic, but it was really cool to experience a real life example. When you asked what color would an “O” be, I thought white and then dismissed that as stupid and random. It was really cool to have that actually validated as a common association with the letter. The association between “C” and yellow was the most fascinating part to me though. I can see how an “O” might be commonly connected with white because we usually read with a white background and majority of the letter is the white space in the center, while an “X” focuses the eye on the black zig zags of the center. Yellow is a random color to assign to “C” and makes a strong case for synesthesia. I think the cultural differences might be a really interesting new direction to take these studies, as well as examining the effects of synesthesia on the blind or deaf community. Do braille letters invoke a synesthetic response? Is this response auditory instead of visual for blind people? And if the visually impaired see a color when they read, do these colors match up with seeing people’s responses? Anyway, cool topic to learn more about, especially with the visual aids you provided!

  2. May 18th, 2013 at 19:45 | #2

    I really liked this study because I always thought that synesthesia was a condition isolated to a small group of people who displayed a constant overlap and blending of the senses. I think Anne’s comment about “O” being white and “X” being black really has some truth to it. It shows that even though adults have the meta-linguistic knowledge to know that “O” and “X” are not inherently connected to a particular shade, some other aspects of cognition can override this knowledge. I am really interested in sound-color synesthesia, and I think it would be a great experiment for these scientists to conduct a study to determine whether “normal” people can “see” sounds in a similar way too!

  3. May 19th, 2013 at 18:27 | #3

    This is a really interesting study because it takes something most of us unconsciously do and gets quantifiable data from it. I would be intrigued to have further experiments see if language-deficient individuals would exhibit similar patterns to the normal population or even if illiterate individuals would match the general populous. I would assume that someone who could not read might not associate “g” with green, just as the younger participants did.

  4. March 20th, 2014 at 13:56 | #4

    Interesting article, and well-written. The image really helped get the point across. Based on these experiments done with color-grapheme synesthesia patients it would be interesting to see how they performed on a partial and whole report sensory memory task. If they automatically see letters as inherently colored, does this represent sensory information, or a form of pattern recognition? I would love to see if they were presented with a letter array, if they would even see the colors at all. If the array is too quick to process for meaning, then they wouldn’t assign the different colors maybe. If they do see the colors but only after processing, assigning them at the reporting stage of the experiment presumably, then they would obviously not do any better on the task than anyone else. However, if they were presented the array and did see it with colors at the sensory level than might we see an improvement in ability to recall them?

  5. October 8th, 2014 at 12:19 | #5

    Synesthesia is without a doubt an interesting and mysterious topic bordering on the supernatural. It almost sounds like a super power to be able to see sound or hear colors, but given that sound, color, and images are all processed by the same part of our body – the brain- it actually isn’t inconceivable that cases could arise when the senses are conflated. That being said I still think it’s a bit of a stretch to suggest that everyone is a part synesthete.

    As much as I’d love to be synesthetic, there are two major problems with the above study that keeps my hopes down. Firstly, and most importantly, the study shows that we associate letters and shapes with colors. The authors even admit that learned associations, at least, such as g with green, may be triggered by the word green. As such it wasn’t so much that g and green trigger the same cognitive reaction, but that g triggered a memory for the word green much like he smell of pines might trigger a memory of your summer camp. But “seeing” your summer camp when you smell pine trees can’t be considered synesthesia, it’s simply a process of remembering.

    This brings us to the second problem: could it be that the visual representation of a letter and not its sound is being associated with colors? The authors make the case that associating letters with colors is synesthesia. This would logically be an auditory/visual conflation, but they admit that in children, this cannot be induced, and instead the visual image of the letter is associated with a color. Such a phenomenon of adding visual attributes to a visual stimulus is not only not synesthesia, but could be an explanation for other situations that would appear to be synesthesia. If indeed O is associated with white because the visual representation of O has a lot of white space in it, the study is simply showing the human tendency towards pattern recognition (or the ascribing of patterns to things that may not even have patterns). This is drastically different clinical cases of synesthesia where auditory input actually triggers abnormal visual processing activity.

    In order to test for synesthesia without brain imaging technology, there would have be some way of looking for consistent simultaneous reactions to different sensory input that is cannot be logically associated. Yet this is difficult because we are not privy to the mental processes leading up to the overt expression of an association. It is hard to tell without analyzing brain activity, whether something is deemed related by memory association or because the sensory information is actually being processed outside of its usual domain. In short, it is hard to differentiate syntesthetes from the imaginative using only subjective means.

    As such the above study makes a terrific case for how our senses come together to form mental representations, but isn’t a particularly compelling argument for synesthesia. Nonetheless I will enjoy asking people what the colors of O and Z are for the next month or two.

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