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Synethesia and the Human Brain: Questions Answered and Questions Raised

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Biology 202
2004 Second Web Paper
On Serendip

Synethesia and the Human Brain: Questions Answered and Questions Raised

MaryBeth Curtiss

"It had never come up in any conversation before. I had never thought to mention it to anyone. For as long as I could remember, each letter of the alphabet had a different color. Each word had a different color too (generally, the same color as the first letter) and so did each number. The colors of letters, words and numbers were as intrinsic a part of them as their shapes, and like the shapes, the colors never changed. They appeared automatically whenever I saw or thought about letters or words, and I couldn't alter them."(1)

At some point, most people consider the way that they perceive the world and how these perceptions may vary from other people's perceptions. We may wonder how the same words sound to different people, or whether or not colors are the same in everyone's eyes. Though most of these differences will never be resolved due to the indescribable nature of sensory observations, one key difference in the perception of the world has been pinpointed, that is, the world of the synesthete. Synesthetes experience language and ideas differently from the average human brain. Ideas, words, letters, numbers and sounds become inherently linked with a color association that manifests itself differently from one synesthete to the next.

Originally, experts in science and psychology were skeptical of the very existence of this rare condition. A recent British study, however has shown that synesthetes were able to recall these complex color and shape associations for significantly longer periods of time than nonsynesthetes. Many experts speculate that these associates are simply the remnants of early methods of learning the alphabet, numbers, shapes and the like, such as colored letters in a book, or multi-colored refrigerator magnets.(2)These associations that survive could be evidence of a very visually-oriented learner, such as many with photographic or visual memories of learned ideas and concepts.

It seems, however, that the neurological patterns of synesthetes are variant from normal patterns in many more ways than association and visualization. Repeated studies show different aptitudes among synesthetes at particular associative exercises, suggesting completely different thought patterns. Some experts now believe that synesthetes actually have a rare "cross-wiring" of the regions of the brain that deal with numbers and computation and colors and visual perception, two regions that are located in close proximity in the brain. Dr. Jeffrey A. Gray has also done some brain scan research that has shown increased activity in the color region of the brain among synesthetes upon hearing words and letters than the control subjects also used in the experiment.(3)

Some synesthetes' also associate particular colors with emotions or experiences. For "Carol", orange is associated with pain, stress and anxiety. When she was experiencing the pain of a toothache and approached her dentist for root canal, she immediately regarded the tooth as being "orange". Further, as the dentist was performing the procedure, her eyes were flooded with the color orange.(4)

The synesthete phenomenon is an important and telling discovery in the field of neurology and brain behavior for many reasons. Firstly, the condition raises the question of what is, in fact, the "normal" perception of letters, numbers, words, and ideas. The very nature of the human senses is called into question. While similar color associations and visualizations may unite synesthetes under a similar experience, does this make nonsynethete experience also similar? Also raised are the questions concerning the source of these associations and what makes them different from other learned associations. While only one in every two-thousand people is regarded as a synesthete, many people of all ages are classified as "visual learners". Many people remember particular facts and experiences by where they were when they learned them or where the sentence was located on the page. Is this mode of memorization related in anyway to synesthesia? Are the associations of synesthesia simply a more complex manifestation of this "visual" way of thinking?

Secondly, the condition of synesthesia raises a new notion of the so-called "cross-wirings" or "cross-firings" in the brain. Popular theories in neurology have suggested that there are distinct areas of strength and weakness in each individual's brain. One particular theory within this notion is that of "left-brained" and "right-brained" individuals. Along these lines, synesthesia suggests a co-operation between two or more regions of the brain that are seemingly unrelated. Whereas the left- and right-brained theory suggests a separation between visual and artistic individuals from number-oriented individuals, synesthesia suggests that these areas are not oppositional, and further, that these regions of the brain may, in fact, work together.

For those with synesthesia, recent research and identification of the condition has provided some answers. The same research, however, has raised countless questions about the nature of the human experience and the differences in individual perceptions of and within this experience. As puzzling as this condition may be, it provides one more unique insight into the individual nature of the human brain.


1) Blue Cats and Chartreuse Kittens, A book by Patricia Lynne Duffy that describes her personal experiences with synesthesia.

2) Synesthetes Show Their Colors, An article by Lila Guterman that explores some of the scientific aspects of the condition, as well as some of the recent research.

3) Synesthetes Show Their Colors: Dr. Jeffrey A. Gray's Experiment, A discussion in Guterman's article that describes one of the recent studies and some of the results.

4) Audio Transcripts from Interviews with "Carol", Interviews with another synesthete that describe some of her unique experiences.



Continuing conversation
(to contribute your own observations/thought, post a comment below)

05/23/2005, from a Reader on the Web

Hi, I watched with interest the Horizon programme on synethesia, and suddenly realised that the condition I have is not that unusual. i do not see col.ours but have always associated certain words and especially names with mainly food items. I always imagined that this was not uncommon, but have never felt it necessary to discuss it with anyone, until about 2 years ago ], when it came out in conversation with my family. They were highly amused, and kept on asking me different questions about it. I also arrange numbers in a pattern and also the days of the week. I do not smell or taste anything just see pictures. I would be grateful for any information on this subject. I am a 62 year old woman and have all my life seen these pictures, yours sincerely Mrs. Maureen Evans

08/06/2005, from a Reader on the Web

I tast in shapes and feelings, coffee would tast round, coke would tast like a ball with sharp points standing out. Stew sould tast like 'n polar flees blanket, butter would tast like cutting meat. Colour would also be in shapes and feelings like you get a flat blue, a sharp red, a hugging green, a scratshing grey, a wicket blue, a wavey purple. A running red. This does not happen al the time it is just sometimes it makes me crazy when i realize the feeling the colour gives me, or the way something tast. I don't know if I am just more aware of these tings sometime then other times. Is that the same as the letter in colours thing?

11/01/2005, from a Reader on the Web

I am an art teacher, and have occasionally asked my students how they perceive such abstract thoughts as the days of the week, the numbers one through 100, the months of the year, etc. I have discovered a significant number (elem. level)have a visual unique to them(including colors associated with no.s and letters). I wonder if the younger students have so far retained this ability, and if the research can tell me at what age this synethetic tendency fades away, if at all. I personally have experienced seeing sound when at rest and hear a sharp, sudden noise. I sometimes hear an electric buzz in my ears simultaneous to a flash of geometric shapes, like a television on the blink,(zig-zags, etc.)and often in high contrast black and white, or possibly yellow or red.


Additional comments made prior to 2007
My son assumed that everyone sees in "shapes". To him, words are shapes and colors. Nouns, emotions, verbs, etc. are different colors and shapes. i.e. The word "Mom" is a light pink cloud. The word happy is a yellow triangle. "Dad" is a blue square. When he said to me, "Don't you see in shapes?", he was surprised at my response. He is 15 now and doesn't see as many shapes as he did when he was a younger learner. He seems to have trouble grasping concepts like math and science and I'm wondering if we can "tap" into his "synesthetes" somehow to help him be a more successful learner. I'm having trouble finding information on his exact phenomona ... Susan Geldmeier, 4 April 2006



I didn't realise that everybody didn't see words and numbers the way I did until my cousin married and I commented on how the colours of her new name complimented her first name, but not as well as her maiden name. My mum was a little perplexed and quized me some more. Years later we watched a documentary that described this as synesthesia and I was amazed that truly everybody didn't see the world the way I did. I still have a hard time understanding how other people see words and colours, are they just black and white? I work as an accountant which most people think is dull, but who wouldn't want to work with all those beautiful colours? And how easy to remember specific results ; ) ... Christine, 12 September 2006


When I was young I was good at mathematics. I finishing third in my class in grade 4. I added in patterns at this time. The patterns were a combination of dots or colours. For example nine dots represented 9, three dots represented 3, Eighteen was speckles of white light on a yellow green background. When I added 9 dots to 9 dots the answer was a 18 picture. When I had to learn multiplication I failed miserably. For example, when asked to multiply 9 X 9 the answer would equal nothing or my visual pattern for eighteen. When told the answer was 81, I would see the 81 pattern but it had no relationship to the question. I remember the 1 and 8 being the wrong way around and I spent hours trying to work out why this was so. Subsequently my math results plummeted. It took me several years to learn multipication by rote or verbal repetition. I do not remember learning addition by rote although I do remember learning addition visually. My teacher would hold up fingers on each of her hands. Students would then be asked to add the numbers indicated on each hand before being allowed to file out of the classroom. I have no idea how I formulated visual patterns and colours for numbers above 9 - it just happened. For some reason I have now forgotten most of the visual patterns for multiple digit numbers.

I did not realise I added up differently until I was in my twenties when coloured wooden blocks were introduced to teach mathematics to young students. It was at this time I realised I was different. Since then I have been curious about my learning processes. For example I am colour defficient in the red green light spectrums. In other words I have less rod and cone receptors in my eyes. This in itself is not remarkable but what I find interesting is how my brain compensates for colour defficiency. For example I use a hightened awareness of tonal value to help identify some colours. This ability backfires when I try to tell pastel greys from pastel greens as these colours share similar tonal values. The interesting point is there is no physical reason why I can't tell greys from greens.

A friend once had fun playing with my colour deficiency. He pointed to a tree and asked me what colour is the tree? I confidently told him it was green. He broke out in laughter and said the tree had brown leaves. At that very instance I saw the tree as green. This sudden change in colour was seamless. It begs the question how does my mind work in relation to seeing colours? I find it curious how my mind tries to compensate for colour deficiency.

Another curiosity about how my mind works is the ability to write in all directions simultaneously using both hands. I can do this in reverse and as a mirror image. I have not come across anyone else who can do this but I'm sure others exist. At times I can do this with ease but on occasions I struggle. I think my mind is always capable of the task but I am right handed and the uncoordinated left can fail me - especially if I am mentally tired. Controlling my left hand interferes with concentrating on the written task.

I also wonder if I may be a tad autistic. I once was asked to fill out a medical form relating to a thyroid problem. Without realising it I continued to turn pages and unwittingly filled out a questionaire relating to autism. I was a bit surprised to find I may demonstrate autism characteristics. I'm unsure but I understand there may be links between autism and synethesia.

As for personality I have obsessive traits and can demonstrate above average artistic and creative abilities. I am not academically gifted.

Make what you want of this but I feel I relate to synethesia even though I do not demonstrate the abilities of a servant ... Kim, 20 September 2006



I see the days of the week as very definite shapes and colours, the months of the year laid out in a horseshoe shape so one can hop off December int January. All numbers are coloured and shaped. I used to keep quiet about when I realised as a child that other people didn't see this. I thought I was weird and it was quite a relief when I discovered what my condition was called. Now I consider it a gift and wonder how others manage without it! ... Joan McDaniel, 17 May 2007


My daughter, Rachel had the musical form of synethesia. She first told me about it when she was 7, in 1981. At that time I could find no information from Dr's or any where else.

She had fallen from her crib as an 18mo old child and had severe vomiting and vertigo all of her life (she died at age 30). She also had mirror movement, what ever movement her left hand and foot did, her right hand and foot had.

She was an extrodinary young woman and had so much to deal with during her life, I only wish that we could have known more about her inner life, possibly we could have found her more support for all the different things she was dealing with.

Please take this information with love, from Rachel's mom ... Ginger, 28 June 2007


Jan Winter's picture


I have just Googled this subject and come accross your site. I had no idea that this was called synesthia or that it was not a normal condition. I am 52 years old and all my life, I have seen the days of the week as different colours. Monday is white, Tuesday is red, Wednesday a dark blue, Thursday pale blue, Friday is green, Saturday is brown and Sunday is black. I don't see anything else in colour/name association, just the days of the week. My family were not even aware of this until It came up in conversation recently. They have asked me on several occasions to tell them what colour the day is and I always repeat the same colours. It has no effect on my moods or how I feel on any specific day, I just associate the days of the week in these colours.
How bizare!

Serendip Visitor's picture

not what I expected

this condition is fascinating and not what i thought it was at all. I had heard of it vaguely although never come across an individual who has it, and everytime I heard about it, I did wonder if I might have it, at least to some mild degree. But based on the above, I don't think so. I had always associated it with crossing of different sensory experiences. For instance for me colours are related to taste and sound, likewise sound is associated with taste and sight. Specific colours, for instance an olive green has a sour taste and while I don't know music well enough to name a note, I can hear it in my head. It is a minor one I think. I have no particular associations of days and numbers, although I wouldn't say they are without character in my mind. I once guessed someone's birthday based on her soft motherly personality and the dates/months I felt best reflected this and I got it right first time, I should add.

However I would clarify, they are simply associations not learning or recall methods. While I can connect these different senses up, they also exist and function individually most of the time. I wouldn't say I hear colour or see noise. Its more of a relationship than a substitution. From reading the comments above it appears as though for synesthetes different sensory input has become fused together.

Anonymous's picture

im not sure if this have

im not sure if this have ever happend to anyone before
but is there a chance of one side of the Human Brain
bigger than the other side?
-like the right side is smaller than the left from the back only..?

Jared Olesen's picture

Social facts as mental images

My earliest memory of this phenomena comes from when I was about 6 or 7. I asked my parents and grandparents if they saw certain food items as the same colors and geometric shapes that I did. I recall that the connection between objects and colors/shapes felt very very natural, as if the colors/shapes really helped me understand and organize the more complicated objects that I was perceiving, like food. It's as if I had created a hierarchy of perception. Basic shapes and colors were at the bottom and everything that was more complicated was based on or connected to those things.

Today, I am 28 and seem to have lost the bottom of the hierarchy. I no longer associate everyday objects like food with basic shapes or colors. However, I do see they days of the week, the alphabet, basic integers 1-100, months of the year, etc. as mental landscapes that I navigate in my mind. The alphabet is three rows of letters, stacked. First row A-I, second J-R, third S-Z. Months are two columns, January at the top through August and September at the top through December. Even though there's only four months in the second column, it manages to take up the same space as the first column. Go figure. Days of the week are arranged in a circle, Sunday at the top and Wednesday on the bottom. The best part is, I know why this is. One of my earliest life memories comes from when I was 3 or 4. I had a He-Man toothbrush holder with a day tracker that had a sword pointing to the days of the week, which were arranged in a circle just as I arrange them in my head! I learned the days of the week from that He-Man toothbrush holder and it determined how I perceive the week cycle for the rest of my life.

I assume that everyone does this kind of thing to a certain degree and some retain it to a greater degree than others. Like many biological phenomenae, it's not likely something you "have" or "don't have", but rather a continuum as infinitely diverse as nature and human experience.

 Katherine Struck's picture


I'm not certain if my experience is related to synathesia or is in a totally different catagory. I have always perceived numbers (especially 1-10) as having gender and personality. Math has always been a challenge- in school, I could get by in geometry, but forget algebra. It's fortunate that I make my living through the arts! Does anyone else recognize this pattern?

bender's picture

I have the same problem, and

I have the same problem, and since I associate shapes with personalities as well as numbers and letters, I have problems with geometry also. It's actually a huge problem for me because, unfortunately, I fail any math class I try to take and cannot seem to explain to people that tutors are not going to help me- though I try very hard. It will also be very hard to explain to those reading my college application...

Anonymous's picture

Me too

Very interesting to hear the comment from 11/01/2005 from a Reader on the Web who said "I personally have experienced seeing sound when at rest and hear a sharp, sudden noise. I sometimes hear an electric buzz in my ears simultaneous to a flash of geometric shapes, like a television on the blink,(zig-zags, etc.)and often in high contrast black and white, or possibly yellow or red"
I have get similar experience in that a sudden noise will sometimes result in me seeing a flash of white with a high contrast geometric patterns. I wonder how many other people get this?

Serendip Visitor's picture

white and black zig zags

i also get see the white and black zig zag pattern when i hear a sharp noise while laying in bed with my eyes closed. i dont 'see in shapes' like the others describe. any one know why?

Gloria Hooshmand's picture


From reading your post I felt a sense of similarity. I constantly see tiny neon movement, like particles or something that will fuse into shapes, patterns and change intensities with sound but more effectively with eye movement. It is all in high contrast and i suffer intense migranes from it. Another symptom is hearing high pitches and fuzzy static, particularily loud when I am around electronic devices.

In regard to my visuals, it is like my eyes have been coated with a veil that is constantly moving and interacting with everything i see. My vision does not change when I close my eyes either, however the colour does intensify.

I have had my eyes and ears checked several times for a physical explaination only to be told that they are working perfectly well.

Anonymous's picture

I have exactly the same

I have exactly the same condition as this. Sudden sounds results in flashes of colourful geometric shapes. green against black zig-zags for electronical sounds, inkly black on white when someone rushes down the stairs, washes of red when the door slams shut. Great to know someone elses is experiencing the same thing! :D

Anonymous's picture


I am 48,and all my life I see the letters of the alphabet,numbers, days of the week, months of the year aranged in patterns. Also my physical and emotional feelings have colours ie I could be feeling brown or red,,,also as a chld I saw my fathers fair/blond hair has having a greenish tinge ! People find this amusing,,,I have only recently realised this is unusual and known as synethesia after having a conversation with someone who also has it.