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Is tasting something you see a form of synesthesia?

Is tasting something you see a form of synesthesia?


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Synesthesia is often stated as "a confusion of the senses" and some of the more common forms include "seeing sounds" or associating letters or numbers with colors. There is also a very rare form of synesthesia called lexical-gustatory synesthesia where one "tastes words."

One thing I've occasionally experienced is that I'll see something and then involuntarily will taste it in my mouth. It's almost always things that are not pleasant, like carpet or copper (things I've tasted when I was a child, I don't regularly eat these things!), and more often when seeing them in large concentrations (e.g. a particularly shaggy carpet, lots of bare copper). Like tasting food, I seem to become acclimated to it pretty quickly.

The closest thing I've heard from other people is they'll say that food "looks so good I can taste it" or something like that. However, I usually hear this for food that also smells very good and as I understand this tasting is because smell and taste are linked (which is normal, not synesthesia). However, I experience this tasting with things that don't have any noticeable smell.

I'm not looking for a diagnosis, but I'd like to know if tasting something you see as I have experienced is something that could possibly fall under the category of synesthesia (or if there is a more mundane explanation).


After a fair amount of research, I came across Noam Sagiv, PhD, a professor at the Centre for Cognition and Neuroimaging who has done research into synesthesia, including visual-gustatory synesthesia (the proper term for seeing-tasting synesthesia). I contacted him about this and he said the following (reproduced with permission):

I can understand your frustration with finding information about this. As you probably know already from trying to look up information on synaesthesia, there is a lot more research on coloured letters and numbers than anything else.

There are a few types of synaesthesia where taste is the inducer (e.g., coloured taste) and a few that involve taste as the synaesthetic experience: For example, musical notes/intervals > taste, or lexical > gustatory that you mentioned already.

In our experience there are also two other variants; there are no published papers yet that I am aware of but we recently accepted an invitation to write one.

1) We tentatively labelled it mirror-taste synaesthesia - this is where you see someone else eating something (with no smell - e.g., on TV) and experience a flavour experience that mirrors the other person's - i.e., similar principle to "mirror touch" synaesthesia, where you see someone being touched, and feel the same experience on your own body. The "social" aspect here is critical - it's not enough to see the food, you need to see another person eating it. My conference presentations covered this one - particularly a brain imaging study we conducted, where we found that basically, we all do something similar, even if only a minority of individuals actually experience it: What we found is very simple, that videos of people eating activate not only the visual cortex (which is what everyone expects) but also the gustatory cortex, despite the absence of direct stimulation of the sense of taste.

2) The other type of gustatory-visual synaesthesia we would like to start exploring soon, is the more direct type you describe. You see something that you've tasted before, and experience the taste involuntarily/automatically and vividly. We have a couple of anecdotal cases but haven't started the formal survey. I expect this to be more common with foods than with non-edible things, but the fact that you get this for some early experiences is consistent with findings from gustatory lexical synaesthesia (where the synaesthetic taste "repertoire" includes things you've eaten as a child, even if you haven't had those for 30 years, and doesn't include things you eat often now, but haven't tried as a child; these things probably consolidate in the first decade of life, probably first half).

We often find we learn new things from synaesthetes and enquiries like yours. I'd be grateful if you did participate in our forthcoming survey, and/or other studies in the lab if you are in the area (West London, UK).

So the short answer from a leading expert in the field is: this area has not been extensively researched, but tasting something you see does indeed seem to be a form of synesthesia, possibly including the situation that I described in the question above.

Dr. Sagiv has also extended the invitation to participate in research on synesthesia to everyone here on CogSci This Site, so feel free to contact him to discuss any synaesthetic experiences, volunteer to participate in a survey, and/or go to his lab in West London.


You ask "if there is a more mundane explanation" and note that you're "not looking for a diagnosis." As you'd expect of course, it seems sensible to conclude that indeed no definitive judgement can be made about the cause of your experiences without some sort of professional assessment. And there are methods available to attempt to make such a determination.1 My cursory research indicates that these are in the process of development, that there is nothing "official," but that some are described as "reliable." Whether there are any applicable to sight-to-taste sensations, I can't say.

As you note, sight-to-taste synesthesia typically involves things like letters, words, numbers, colors, or shapes. I did find a few examples of perceptions similar to yours. One relates to a man who experienced synesthetic taste sensations of "synthetic inedibles (wax candles, for example)."2 Another is a reference to the idea that some synesthetes "may connect the sense of sight to taste so that every time they see a sailboat they will taste a donut'."3 Finally, there is another mere supposition that "llamas [may] look like sweet and sour sauce."4 These examples seem to confirm an observation that "[t]here are a lot of synesthete stories around the Internet, but many of them are lost within blog comments, outdated forums or hard-to-read Tumblr threads."5

"A more mundane explanation," in this case related to more common forms of "blended senses," is found in the theory that "people who have Synesthesia just retain color memories from childhood. An example would be colorful alphabetical or numerical magnets that the child had played with. This theory, however, does not explain all aspects of the condition."6 It seems impossible, based on the information available, to even speculate about the likelihood that your sensations result from childhood experiences, although you do note that you may have " tasted [cooper and carpet] when [you were] a child."

You may be interested in a recent study of so-called " learned synesthesia," examining "whether traits typically regarded as markers of synesthesia can be acquired by simply reading in color."7

Is there any history of synesthesia in your family? "It is believed that one gene which is responsible for causing Synesthesia gets passed from one generation to the next by the X chromosome, as a Dominant trait (Smilek, 2005). This could explain why Synesthesia runs in families."8

Finally, you may be familiar with the work of Richard E. Cytowic, a medical doctor and an Associate Professor of Neurology at George Washington University, and a leading authority on synesthesia. He is the author of The Man Who Tasted Shapes, and was featured a few years ago on the American television program "60 Minutes." He may be interested in your experiences. You might want to contact him.

1 "There are several screening techniques that are used in diagnosing and confirming Synesthesia.… These are called pop-out, segregation, cross-modality imagery, and the Stroop test." - from Synesthesia: The Medical Condition of Associating Letters and Numbers With Certain Colors (2007), by Jennifer Rossman, citing Crane, Carol A. (2006). Synesthesia. A neuropsychological and familial study of developmental synesthesia. Dissertation Abstracts International, 66(8-B), 4477,

2 A Summary of Current Ideas on Synesthesia (2007?), by Megan Davis, for an undergraduate seminar in Cognitive Psychology at Goucher College.

3 A FAQ about synesthesia on a blog published on wikispaces.com.

4 A document about synesthesia published on everything2.com

5 Maureen Seaberg's Synesthesia Story (Video), a blog post on blendedsenses.com

6 Rossman, citing Ramachandran, Vilayanur S. & Hubbard, Edward M. (2005). Hearing colors, tasting shapes. Scientific American Mind,16, 16-23.

7 Pseudo-Synesthesia through Reading Books with Colored Letters (2012), by Olympia Colizoli, Jaap M. J. Murre, and Romke Rouw.

8 Rossman, citing Smilek, Daniel, & Dixon, Mike J. (2005) Synesthesia: Discordant male monozygotic twins. Neurocase,11(5), 363-370.


Test yourself for synaesthesia

Synesthete.org is a website that has a series of online tests where you can test yourself for synaesthesia – the condition where senses are crossed so, for example, you might be able to taste shapes or see colours associated with specific numbers.

The site is run by the Eagleman Lab at the Baylor College of Medicine who study links between perception and action, as well as the curious world of synaesthesia.

If you’re a researcher, you can also use the site to test and collect results on your own participants, and the same tests are also available as downloadable software for the Matlab package.

It’s now known that synaesthesia is partly inherited, so if you find that you or one of your family members seems to have the condition, others in the family may also have similar abilities.

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The complex study of synesthetes (otherwise known as the story of how I fell down the internet rabbit hole)

This post is brought to you by a long line of google searches, links to other articles and me getting distracted by yet another cool fact and then not being able to decide how to focus this post into a reasonable length. Initially, I planned to write about synesthesia (i.e. a really cool phenomenon that I’ll explain soon but which essentially causes people to have unusual overlapping sensory experiences) and how it relates to other disorders and phenomenons linked to neuroplasticity and incorrect wiring of the brain. But then, during my research, I found an article discussing how advertisers use “culturally synesthetic” associations (the associations between various sensory stimuli (for examples, colors and flavors) that are largely common across all individuals in a society) to influence our perceptions and feelings about their products. Then, because this didn’t sound like enough neurobiology for me, I started looking up the theories behind how synesthesia actually occurs in the brain, and somehow came across the phenomenon of mirror-touch synesthesia in which a person observes another person touching something or being touched and feels like they themselves are also being touched which was super interesting and has a lot of implications for our understanding of empathy, consciousness, and the brain.

I got distracted once again and found a list on Wikipedia of all the famous people who are believed to have/have had synesthesia (the list overwhelmingly consists of artists, musicians, and composers, and includes Kanye West, Marilyn Monroe, Van Gogh, and Hans Zimmer). This got me to think about the ways in which you can use psychology and knowledge about perception to create tests that can be used to determine whether someone is an actual synesthete or not.

By this point (with 20+ tabs open and still no real focus) I realized I had found far too many sources and topics to be condensed into a single post. Long story short, what I’ve learned is that there are just too many cool things to study and learn about synesthesia that it is impossible to cover everything in a post that anyone would actually want to read in its entirety, so I’ve decided to force myself to focus on just one thing: current scientific theories about how synesthesia comes to occur in the brain (since this is supposed to be a blog about neuroscience). (Don’t worry, I’ll link all the cool articles I found at the bottom in case anyone is interested in learning more!)

First, I’ll start off by better explaining what synesthesia is and the many different ways in which it manifests. Synesthesia is a condition that causes involuntary ‘blending’ of the senses. Essentially, this means that when a synesthete experiences a particular sensory input, another experience occurs alongside in a different sense. For example, some synesthetes experience a taste in their mouth when they hear a given word, or see shapes, movement and colors when they detect certain smells. There are about as many ways in which synesthesia can manifest as there are ways to pair any sense with another (some estimates suggest as many as 80 variations). However, some forms, such as grapheme-color (letters have different color associations), chromesthesia (sounds cause colors to be experienced), and special sequence synesthesia (seeing numerical sequences such as dates or months as points in space around them) are much more common than others. Synesthesia is estimated to occur in 3.7% of the general population, although it is likely that this number is higher due to the fact that many people don’t realize they have it until someone convinces them that, for instance, other people don’t usually see a specific color when they think of each letter.

As synesthesia is a very personal and individual experience and can be difficult to observe in another person (although it is important to note that sometimes the associations can be so overwhelming and intrusive that it can be difficult for some synesthetes to function normally, especially in highly stimulating environments such as crowds or public spaces), it may leave you wondering how you could ever prove that someone does or does not have synesthesia after all, couldn’t they just have memorized a color for each letter and be faking it? How can you determine that the associations are actually involuntary and consistent across time? There are a variety of tests that use existing knowledge about perception to test whether the person is actually having a perceptual experience or not.

Source: synesthesiatest.org

For example, a common test for grapheme-color synesthesia is to present a person with a picture full of several black numbers or letters, which consist of mostly one number with a few instances of another number randomly sprinkled in (see picture to the left). A person without synesthesia sees a bunch of black shapes and has difficulty picking out which numbers are different from the rest, but a person with synesthesia will automatically associate colors with the numbers and thus will be able to quickly pick out the numbers that are ‘different colored’ (see picture to the right). This test can be effective for diagnosing people who have very strong synesthetic associations between letters/numbers and colors, but I don’t think it is necessarily as effective for people who sort of just ‘feel like’ a certain letter is supposed to be a certain color. Other more abstract forms of synesthesia such as sound-color or touch-flavor are more difficult to definitively prove, but another common method that is used to test for many types of synesthesia is to have a person report their synesthetic associations and then retest them again later to see if they are able to report the same associations. For example, in 1987, a group of researchers tested a word-color synesthete by asking her to describe the color that 100 random words triggered. A year later they randomly tested her again and she was able to report the same associations with 90% accuracy, while a group of non-synesthetic controls performing the same tests only two weeks apart only showed 20% consistency.

Ok, now that I have convinced you that synesthesia is real and can be scientifically verified in a variety of ways, you might be wondering about the underlying neurobiology of it all. The first insights came when Paulesu et al. (1995) used positron-emission tomography (a method of imaging brain activity), to show that word-color synesthetes, when presented with auditory words but not when presented with pure tones, exhibited activation in various regions of the brain not active in non-synesthetes doing this task. These regions included many involved in integration of color with shape and in verbal tasks which require attention to visual features of objects to which words refer, but notably did not include lower visual processing areas. This suggests a measurable, underlying neurobiological difference in the brains of synesthetes.

Despite evidence that it has a biological cause, there is still no definitive understanding of how synesthesia originates in the brain. There are countless theories, some involving genetics, increased myelination in certain axons (essentially causing signals in the brain to travel faster and more easily across various regions), or more molecular factors affecting inhibitory processes in some neuronal pathways, which results in those signals passing backwards from multisensory areas to single-sensory areas in a way that they are not normally allowed to. Research has shown that some types of synesthesia are associated with genetic factors, even locating specific regions of DNA that might be implicated in colored sequence synesthesia. Other research suggests that, more specifically, a genetically driven overabundance of neural connections in the brain leading to unusual wiring between multiple sensory areas might be the cause.

While there is still much we don’t understand, what we do know is that synesthesia is an extremely complex and fascinating phenomenon, the study of which has implications for a broad array of other areas of neuroscience including perception, consciousness, the effects of psychedelic drugs, disorders like schizophrenia, learning and memory, the list goes on and on. Further research is needed in order to more fully understand synesthesia, but maybe we can one day unlock the secrets to its development so that everyone can experience it. Wouldn’t you like to see beautiful colors or taste chocolate when you listen to your favorite song?


Synesthesia

Synesthesia (also spelled synæsthesia or synaesthesia, plural synesthesiae or synaesthesiae)—from the Ancient Greek σύν (syn), "together," and αἴσθησις (aisthēsis), "sensation" — is a neurologically based phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. People who report such experiences are known as synesthetes.

Synesthesia can occur between nearly any two senses or perceptual modes. Given the large number of forms of synesthesia, researchers have adopted a convention of indicating the type of synesthesia by using the following notation x → y, where x is the "inducer" or trigger experience, and y is the "concurrent" or additional experience. For example, perceiving letters and numbers (collectively called graphemes) as colored would be indicated as grapheme → color synesthesia. Similarly, when synesthetes see colors and movement as a result of hearing musical tones, it would be indicated as tone → (color, movement) synesthesia.

While nearly every logically possible combination of experiences can occur, several types are more common than others.


Grapheme → color synesthesia

How someone with synesthesia might perceive certain letters and numbers.

Another example of real synaesthesia for letters and numbers.

In one of the most common forms of synesthesia, grapheme → color synesthesia, individual letters of the alphabet and numbers (collectively referred to as graphemes), are "shaded" or "tinged" with a color. While synesthetes do not, in general, report the same colors for all letters and numbers, studies of large numbers of synesthetes find that there are some commonalities across letters (e.g., A is likely to be red).


Sound → color synesthesia

In sound → color synesthesia, individuals experience colors in response to tones or other aspects of sounds. Simon Baron-Cohen and his colleagues break this type of synesthesia into two categories, which they call "narrow band" and "broad band" sound → color synesthesia. In narrow band sound → color synesthesia (often called music → color synesthesia), musical stimuli (e.g., timbre or key) will elicit specific color experiences, such that a particular note will always elicit red, or harps will always elicit the experience of seeing a golden color. In broadband sound → color synesthesia, on the other hand, a variety of environmental sounds, like an alarm clock or a door closing, may also elicit visual experiences.

Color changes in response to different aspects of sound stimuli may involve more than just the hue of the color. Any dimension of color experience (see HSL color space) can vary. Brightness (the amount of white in a color as brightness is removed from red, for example, it fades into a brown and finally to black), saturation (the intensity of the color fire engine red and medium blue are highly saturated, while grays, white, and black are all unsaturated), and hue may all be affected to varying degrees.[26] Additionally, music → color synesthetes, unlike grapheme → color synesthetes, often report that the colors move, or stream into and out of their field of view.

Like grapheme → color synesthesia, there is rarely agreement among music → color synesthetes that a given tone will be a certain color. However, when larger samples are studied, consistent trends can be found, such that higher pitched notes are experienced as being more brightly colored.[19] The presence of similar patterns of pitch-brightness matching in non-synesthetic subjects suggests that this form of synesthesia shares mechanisms with non-synesthetes.[19]


Number form synesthesia

A number form is a mental map of numbers, which automatically and involuntarily appears whenever someone who experiences number-forms thinks of numbers. Number forms were first documented and named by Francis Galton in "The Visions of Sane Persons". Later research has identified them as a type of synesthesia. In particular, it has been suggested that number-forms are a result of "cross-activation" between regions of the parietal lobe that are involved in numerical cognition and spatial cognition. In addition to its interest as a form of synesthesia, researchers in numerical cognition have begun to explore this form of synesthesia for the insights that it may provide into the neural mechanisms of numerical-spatial associations present unconsciously in everyone.


Ordinal-linguistic personification (OLP, or personification for short) is a form of synesthesia in which ordered sequences, such as ordinal numbers, days, months and letters are associated with personalities. Although this form of synesthesia was documented as early as the 1890s modern research has, until recently, paid little attention to this form.

For some people in addition to numbers and other ordinal sequences, objects are sometimes imbued with a sense of personality, sometimes referred to as a type of animism. This type of synesthesia is harder to distinguish from non-synesthetic associations. However, recent research has begun to show that this form of synesthesia co-varies with other forms of synesthesia, and is consistent and automatic, as required to be counted as a form of synesthesia.


Lexical → gustatory synesthesia

In a rare form of synesthesia, lexical → gustatory synesthesia, individual words and phonemes of spoken language evoke the sensations of taste in the mouth.

Jamie Ward and Julia Simner have extensively studied this form of synesthesia, and have found that the synesthetic associations are constrained by early food experiences. For example, James Wannerton has no synesthetic experiences of coffee or curry, even though he consumes them regularly as an adult. Conversely, he tastes certain breakfast cereals and candies that are no longer sold.

Additionally, these early food experiences are often paired with tastes based on the phonemes in the name of the word (e.g., /I/, /n/ and /s/ trigger James Wannerton’s taste of mince) although others have less obvious roots (e.g., /f/ triggers sherbet). To show that phonemes, rather than graphemes are the critical triggers of tastes, Ward and Simner showed that, for James Wannerton, the taste of egg is associated to the phoneme /k/, whether spelled with a "c" (e.g., accept), "k" (e.g., York), "ck" (e.g., chuck) or "x" (e.g., fax). Another source of tastes comes from semantic influences, so that food names tend to taste of the food they match, and the word "blue" tastes "inky."

Do you have it or know someone who does? What are your experiences with it?

If you have any questions about the condition itself or other's experiences, please add them to the conversation as well. I know I will.

I myself have only slightly expressed synesthesia, and hadn't realized not everyone saw words the way I did until the last year or so. As such, I'm curious about the experiences of others.


General Psychology

Like all of Dr. Ramamchandran's cases this one is by far the most bizarre and interesting. I do not agree that this can condition could be associated with being a product of childhod memories and associations occuring in the brain. The best explanation is clearly that synesthesia is another situation that is best explained in neurologist terms. Neurology helps to explain almost all disorders because the brain is the source and provider of all our information dealing with our emotions and movements. Synesthesia is a result of "mixed sensations: a stimulus in one sensory modality (e.g., hearing) involuntarily elicits a sensation/experience in another modality (e.g. vision). Likewise, perception of a form (e.g., a letter) may induce an unusual perception in the same modality (e.g. a color)"(synesthe.org).

This symptom is very interesting and convinces how human body is formed scientifically. About the brain parts' connection and how they are wired all together then how one parts send signal to stimulate the other parts. I feel sorry about the patients who have this mental disorder but it is very interesting to me as I imagine what's gonna happen if I can manipulate this brain connections. For example, if I can connect my brain parts that govern my vision with a brain parts that govern my smelling sensory parts. Then when smell something I can draw that smell because I can see it. Also as I see something I can smell that view. How exciting would it be.

This was very interesting. Hearing Colors and tasting shapes.. I can't imagine what it feels like.. And this case is also the cause about the brain. Learning of Dr. Ramamchandran's theoris was really new thing and interesting for me.

As someone who has synaesthesia, I should like to correct your belief that we are "patients" with "mental disorders". The condition is in fact not a disorder at all, just a harmless perceptual difference, which many people see as a gift. Some researchers, Ramachandran included, see it as contributing to creativity, and it can certainly aid memory. It's not that weird, either– it now seems it's very common and that many people have it without knowing, since it doesn't usually cause problems and seems perfectly natural if you have it. (Do YOU by any chance often think letters or numbers have colours? You don't have to actually see them– just making the association in your head is enough!)

There is unfortunately a common perception that it's a form of mental illness or something, probably because it's "neurological" and has a long name that sounds a bit like "schizophrenia". Also, media treatment is often very sensational and gives the impression that people's senses are totally messed up so that they can't interpret sensory impressions. This is entirely wrong. Please look up the Wikipedia page on synaesthesia and related links if you don't believe me.

Or you could try these:
http://www.bbc.co.uk/health/conditions/synaesthesia1.shtml
http://www.scholarpedia.org/article/Synesthesia
http://www.naropa.edu/consciousness/synesthesia.cfm
http://www.uksynaesthesia.com/
http://www.syn.sussex.ac.uk/
http://www.maccs.mq.edu.au/research/projects/synaesthesia/index.html
http://med.uth.tmc.edu/comm/alumniMag/2006-Spring/articles/article-03a-brain.html

Authoritative enough for you?

I am not trying to be rude here, but you must understand how unpleasant it is to have people casually assuming there's something wrong with your head!

On the upside– there's no need for you to feel sorry for anyone! This is no more a mental disorder than being left-handed is.

P.S. I'm going to assume you're a nice person and won't come to my blog and harass me for saying this. Just in case you were thinking of it, please don't. I've had a very nasty experience like that, and I don't want a repeat.

I just thought I'd come back and say a few more things about synaesthesia, which is a very misunderstood phenomenon.

Contrary to what people seem to think, it's not like one sense replaces another– you don't hear instead of seeing, or anything weird like that. Also, most people who do this don't actually see the colours physically– that's very rare– they just associate colours with sounds or letters or numbers– L is pale blue, F is green, M is red etc. (However, now and then I have for a moment seen very black or white text as being tinged with "my" colours.)

The only drawback I have ever found to it are that I can get a slight feeling of disquiet from seeing words written in the "wrong" colours, and that I can sometimes get distracted by music and musical tones, just because I start listening to the colours.

It's not harmful, and really not that bizarre. in fact some researchers think just about everyone experiences certain basic forms of synaesthesia, and that it has influenced the development of language and especially metaphor.

(All the above applies to "developmental synaesthesia", the kind thought to be caused by a gene mutation. You can also get it from brain damage, in which case it is a pathological symptom.)


We would like to give a special thank you to SC for her time, interest, and dedication to our experiments. We thank Ricardo van Buren for help with the experimental setup and data collection, all of the control participants, as well as Henk Bas and Jurjen Simmelink for introducing us to SC.

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Gottfried, J. A., Deichmann, R., Winston, J. S., and Dolan, R. J. (2002). Functional heterogeneity in human olfactory cortex: an event-related functional magnetic resonance imaging study. J. Neurosci. 22, 10819�.

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Hänggi, J., Beeli, G., Oechslin, M. S., and Jäncke, L. (2008). The multiple synaesthete ES.: neuroanatomical basis of interval-taste and tone-colour synaesthesia. Neuroimage 43, 192�. doi: 10.1016/j.neuroimage.2008.07.018

Jenkinson, M., Bannister, P., Brady, M., and Smith, S. (2002). Improved optimization for the robust and accurate linear registration and motion correction of brain images. Neuroimage 17, 825�. doi: 10.1006/nimg.2002.1132

Jenkinson, M., Beckmann, C. F., Behrens, T. E., Woolrich, M. W., and Smith, S. M. (2012). Fsl. Neuroimage 62, 782�. doi: 10.1016/j.neuroimage.2011.09.015

Jenkinson, M., and Smith, S. (2001). A global optimisation method for robust affine registration of brain images. Med. Image Anal. 5, 143�. doi: 10.1016/S1361-8415(01)00036-6

Jones, C., Gray, M., Minati, L., Simner, J., Critchley, H., and Ward, J. (2011). The neural basis of illusory gustatory sensations: two rare cases of lexical–gustatory synaesthesia. J. Neuropsychol. 5, 243�. doi: 10.1111/j.1748-6653.2011.02013.x

Meier, B., and Rothen, N. (2007). When conditioned responses 𠇏ire back”: bidirectional cross-activation creates learning opportunities in synesthesia. Neuroscience 147, 569�. doi: 10.1016/j.neuroscience.2007.04.008

Ogawa, H., Wakita, M., Hasegawa, K., Kobayakawa, T., Sakai, N., Hirai, T., et al. (2005). Functional MRI detection of activation in the primary gustatory cortices in humans. Chem. Senses 30, 583�. doi: 10.1093/chemse/bji052

Pierce, A. H. (1907). Gustatory audition a hitherto undescribed variety of synaesthesia. Am. J. Psychol. 18, 341�. doi: 10.2307/1412597

Richer, F., Beaufils, G., and Poirier, S. (2011). Bidirectional lexical–gustatory synesthesia. Conscious. Cogn. 20, 1738�. doi: 10.1016/j.concog.2010.12.015

Rothen, N., Nyffeler, T., von Wartburg, R., Müri, R., and Meier, B. (2010). Parieto-occipital suppression eliminates implicit bidirectionality in grapheme-colour synaesthesia. Neuropsychologia 48, 3482�. doi: 10.1016/j.neuropsychologia.2010.07.032

Rouw, R., and Scholte, H. S. (2007). Increased structural connectivity in grapheme-color synesthesia. Nat. Neurosci 10, 792�. doi: 10.1038/nn1906

Rouw, R., Scholte, H. S., and Colizoli, O. (2011). Brain areas involved in synaesthesia: a review. J. Neuropsychol. 5, 214�. doi: 10.1111/j.1748-6653.2011.02006.x

Simner, J., Cuskley, C., and Kirby, S. (2010). What sound does that taste? Cross-modal mappings across gustation and audition. Perception 39, 553. doi: 10.1068/p6591

Simner, J., and Haywood, S. L. (2009). Tasty non-words and neighbours: the cognitive roots of lexical-gustatory synaesthesia. Cognition 110, 171�. doi: 10.1016/j.cognition.2008.11.008

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Keywords: synesthesia, fMRI, priming, perception, memory, gustation, olfaction

Citation: Colizoli O, Murre JMJ and Rouw R (2013) A taste for words and sounds: a case of lexical-gustatory and sound-gustatory synesthesia. Front. Psychol. 4:775. doi: 10.3389/fpsyg.2013.00775

Received: 27 July 2013 Accepted: 02 October 2013
Published online: 23 October 2013.

Michael Banissy, Goldsmiths University of London, UK

Jürgen Hänggi, University of Zurich, Switzerland
Catherine L. Jones, University of Exeter, UK

Copyright © 2013 Colizoli, Murre and Rouw. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.


Can Synesthesia Be Learned?

In class this week, we have been very curious about the origins of synesthesia. Synesthesia is a condition in which sensory experiences evoke other perceptual experiences that are not typically elicited in most individuals. A common example is seen in individuals who associate specific colors with certain letters or graphemes. We have been asking many questions, including: How much of synesthesia is genetic? How much is dependent on our environment? Is it dependent on exposure to certain features in our culture, possibly during a “critical period”? For example, could a person develop sound to color synesthesia with a limited exposure to sound in childhood?

A study conducted by Bor, Rothen, Schwartzman, Clayton, and Seth (2014) investigated whether or not adults without synesthesia could be trained to acquire these synesthetic experiences. These non-synesthetes were trained to learn 13 specific letter-color associations by engaging in various memory and reading tasks over the course of 9 weeks. After training, participants took a variety of tests used to measure genuine synesthesia, like the color consistency task, the synthetic Stroop task, and a classical conditioning test—and they all “passed” as actually having synesthesia! Days after training, participants showed behavioral and physiological evidence for synesthesia, reporting perceived color experiences for colorless letters. Furthermore, participants were experiencing these strong perceptions inside and outside of the lab setting and across different contexts.

However, participants gained more than these perceptions. Bor et al. (2014) also found that participants who completed training showed an increase in their IQ by an average of 12 points, compared to controls. This suggests that there is something about learning synesthetic links that can result in an enhanced cognitive ability. These results are useful and exciting to explore. It is possible that this training could help individuals at risk for dementia or other diseases that cause cognitive decline.

In Bor et al.’s study (2014), the training was intense and lasted over a period of 9 weeks. However, the researchers note that some participants demonstrated synesthesia after just 5 weeks! So, it seems that there are some aspects of synesthesia that can be learned. The “genuineness” of their synesthesia, however, is under debate. In most participants, this ability faded away over time. This study made me wonder, what else could we learn if we are committed to this sort of training? For example, could we learn other special skills that are present in conditions like Savant Syndrome?

Bor, D., Rothen, N., Schwartzman, D., Clayton, S., & Seth, A. (2014). Adults Can Be Trained to Acquire Synesthetic Experiences. Scientific Reports, 4. doi: 10.1038/srep07089


Synesthesia allows authors to deliver another level of description in literature. It challenges readers to think out of the box and reinterpret their senses as they know them. Most importantly, though, synesthesia is a unique device that very few authors employ, making it quite notable and distinctive when an author does use it.

Example 1

The beloved children’s fantasy novel The Phantom Tollbooth is rich with descriptions that use synesthesia. The author Norton Juster is a synesthete, and he used his own sensory perceptions to inspire parts of the book, as you can see in the following passage from Chapter 10: A Colorful Symphony:

“I don’t hear any music,” said Milo.
“That’s right,” said Alec “you don’t listen to this concert—you watch it. Now, pay attention.”
As the conductor waved his arms, he molded the air like handfuls of soft clay, and the musicians carefully followed his every direction.
“What are they playing?” asked Tock, looking up inquisitively at Alec.
“The sunset, of course. They play it every evening about this time.”
“They do?” said Milo quizzically.
“Naturally,” answered Alec “and they also play morning, noon and night, when, of course, it’s morning, noon and night. Why, there wouldn’t be any color in the world unless they played it.”

Here, Juster uses synesthesia in the book’s fantasy world to express the idea of a connection between music and colors. Alec explains that the sunset they see every day is actually created by instruments that play colors instead of musical notes. He also tells Milo to “watch” the concert, rather than listen to it, because the instruments will create the colors of the sunset and all of the colors in the world.

Example 2

In Inferno of the epic poem The Divine Comedy, Dante uses synesthesia to emphasize a place’s harshness:

E’en such made me that beast withouten peace,
Which, coming on against me by degrees
Thrust me back thither where the sun is silent.

Here, Dante refers to a place “where the sun is silent.” Our perception of the sun is usually associated with our sense of sight (its brightness) and touch (its heat), but not with any sort of sound. By asserting that the sun is silent, Dante is highlighting the fact that it is absent from the place he is describing. His description has a greater impact than “the sun can’t be seen” or “there is no heat”—“silent” suggests a dark, lifeless, cold and colorless place that never sees the sun.


Mirror-Touch Synesthesia: Pain & Empathy

If you’ve ever accompanied a friend or family member on a doctor’s visit and sat in the very room the checkup ritual took place, you’ve likely had the fortune of empathizing with that friend or family member, watching as the stethoscope was pressed to the bare back, the reflex hammer hit the knee, or the vaccination needle penetrated flesh. Now, for a second (and no longer), imagine that, in watching these actions take place, you also felt them. A tingle on your back. A knock to your knee. A pinch on your skin. That is mirror-touch synesthesia.


What It's Like To Experience Synesthesia: The Taste Of Music And Colors Of Language

Synesthesia is an involuntary and consistent joining of two different senses. What's it like to possess this unusual gift of perception? Photo courtesy of Shutterstock.

Synesthesia is an involuntary joining of two different senses. A person might see the color red, for example, whenever they hear a bell ring. Or, the sound of music played on a piano might evoke the taste of coffee for another. An important aspect of synesthesia is consistency — the linked perception is the same every time so that the number "5" will always be red, while the number "2" will always be green.

What is it like to experience synesthesia? A common theme in stories from synesthetes is the moment they discover they are different. "I nodded meekly but inside, I was reeling," wrote one synesthete when he first discovered others did not perceive the world as he did. "No colors? Everyone lived in a white word where numbers and letters were simply black? And music didn’t fill the air with sparkles and waves of colored light? Did that mean they didn’t see auras around people either? Their worlds were colorless?"

It's also important to understand synesthetes do not regard the additional perception as imaginary — the experience of a blend of senses is just as vivid and real as a single sense is for others. Just as you would not doubt you are seeing red, for instance, a synesthete does not doubt that a song by Sonic Youth is pale yellow. The pairing of senses, individual and varied though they may be, are not infinite just as the senses are not infinite. Some researchers estimate records of 35 or so different subtypes, such as taste-hearing (hearing a sound produces a taste) and sound-touch (feeling an object produces a sound). The most common are color-graphemic, in which number, letters, and/or shapes produce colors (or sometimes simple patterns) and color-auditory, in which voices, music, and/or random noise produces colors, textures, and shapes.

Should synesthetes consider themselves lucky?

Many do, though sometimes they may feel isolated and worry about what others will think. “The oddest thing about all this is that I thought this was how everyone perceived the world until about 8th grade when I asked a childhood friend about how he liked the purple tone a certain song had and he looked at me like I had 4 heads,” wrote a male synesthete. “I had something similar happen in a college music room where I was tired and not thinking and the teacher asked what I thought of a particular piece and I blurted out ‘I hate it it is too pale yellow’ which of course caused half the room (including the teacher) to freak out or just start laughing.”

Disharmony may sometimes bother other synesthetes, who prefer the regularity of their own visions. Seeing a poster with the numbers in color, for instance, one synesthete commented, “If a 4 is purple instead of green it makes me mad.” A synesthete who tastes language said, “I taste the words whether I read them in a book or hear them in a conversation. The downside of this is when I am eating something and the taste of the word spoken does not go very well with the taste of whatever I am eating.”

One synesthete who routinely sees colors when she hears music also reports a more abstract linking between personality and color: “This is good, it helps me choose good friends,” she notes, adding “purple people are snobbish.”

Friendship is a necessary requirement for confidence with many who possess this unusual ability. “I usually don't share with many people because it takes way too much time to explain,” wrote another synesthete. Yet he also strongly believes this trait is a gift. “I could not imagine a life without it.”

Synesthesia occurs in about four percent of the population. In particular, women have greater odds of being born with the condition in the U.S., studies show that three times as many women as men, while in the UK, the ratio is six to one. This difference in prevalance may be tied to the fact that the condition also runs in families. For this reason, researchers believe there is a genetic component even though the specific genes underlying synesthesia are still unknown. Oddly, synesthetes are more likely to be left-handed than the general population.

Neuroimaging studies show that there are unusual connections in the brains of synesthetes regions not usually wired together are linked and this is what causes a sensation along one channel to automatically trigger a perception in another. A recent study found that there is a link between synesthesia and autism spectrum conditions. Autism occurs in one percent of the population. Yet when researchers tested 164 adults with autism and 97 adults without the condition, synesthesia occurred in nearly one in every five people (20 percent) with autism — much greater than the four percent found in the population at large. The similarities between the two conditions are striking as with synesthesia, neuroimaging studies have also discovered greater connectivity in the brains of people with autism as compared to those without the condition.


We would like to give a special thank you to SC for her time, interest, and dedication to our experiments. We thank Ricardo van Buren for help with the experimental setup and data collection, all of the control participants, as well as Henk Bas and Jurjen Simmelink for introducing us to SC.

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Jenkinson, M., and Smith, S. (2001). A global optimisation method for robust affine registration of brain images. Med. Image Anal. 5, 143�. doi: 10.1016/S1361-8415(01)00036-6

Jones, C., Gray, M., Minati, L., Simner, J., Critchley, H., and Ward, J. (2011). The neural basis of illusory gustatory sensations: two rare cases of lexical–gustatory synaesthesia. J. Neuropsychol. 5, 243�. doi: 10.1111/j.1748-6653.2011.02013.x

Meier, B., and Rothen, N. (2007). When conditioned responses 𠇏ire back”: bidirectional cross-activation creates learning opportunities in synesthesia. Neuroscience 147, 569�. doi: 10.1016/j.neuroscience.2007.04.008

Ogawa, H., Wakita, M., Hasegawa, K., Kobayakawa, T., Sakai, N., Hirai, T., et al. (2005). Functional MRI detection of activation in the primary gustatory cortices in humans. Chem. Senses 30, 583�. doi: 10.1093/chemse/bji052

Pierce, A. H. (1907). Gustatory audition a hitherto undescribed variety of synaesthesia. Am. J. Psychol. 18, 341�. doi: 10.2307/1412597

Richer, F., Beaufils, G., and Poirier, S. (2011). Bidirectional lexical–gustatory synesthesia. Conscious. Cogn. 20, 1738�. doi: 10.1016/j.concog.2010.12.015

Rothen, N., Nyffeler, T., von Wartburg, R., Müri, R., and Meier, B. (2010). Parieto-occipital suppression eliminates implicit bidirectionality in grapheme-colour synaesthesia. Neuropsychologia 48, 3482�. doi: 10.1016/j.neuropsychologia.2010.07.032

Rouw, R., and Scholte, H. S. (2007). Increased structural connectivity in grapheme-color synesthesia. Nat. Neurosci 10, 792�. doi: 10.1038/nn1906

Rouw, R., Scholte, H. S., and Colizoli, O. (2011). Brain areas involved in synaesthesia: a review. J. Neuropsychol. 5, 214�. doi: 10.1111/j.1748-6653.2011.02006.x

Simner, J., Cuskley, C., and Kirby, S. (2010). What sound does that taste? Cross-modal mappings across gustation and audition. Perception 39, 553. doi: 10.1068/p6591

Simner, J., and Haywood, S. L. (2009). Tasty non-words and neighbours: the cognitive roots of lexical-gustatory synaesthesia. Cognition 110, 171�. doi: 10.1016/j.cognition.2008.11.008

Simner, J., and Logie, R. H. (2008). Synaesthetic consistency spans decades in a lexical–gustatory synaesthete. Neurocase 13, 358�. doi: 10.1080/13554790701851502

Simner, J., Mulvenna, C., Sagiv, N., Tsakanikos, E., Witherby, S. A., Fraser, C., et al. (2006). Synaesthesia: the prevalence of atypical cross-modal experiences. Perception 35, 1024�. doi: 10.1068/p5469

Simner, J., and Ward, J. (2006). Synaesthesia: the taste of words on the tip of the tongue. Nature 444, 438. doi: 10.1038/444438a

Small, D. M. (2010). Taste representation in the human insula. Brain Struct. Funct. 214, 551�. doi: 10.1007/s00429-010-0266-9

Small, D. M., Gerber, J. C., Mak, Y. E., and Hummel, T. (2005). Differential neural responses evoked by orthonasal versus retronasal odorant perception in humans. Neuron 47, 593�. doi: 10.1016/j.neuron.2005.07.022

Smith, S. M. (2002). Fast robust automated brain extraction. Hum. Brain Mapp. 17, 143�. doi: 10.1002/hbm.10062

Smith, S. M., Jenkinson, M., Woolrich, M. W., Beckmann, C. F., Behrens, T. E., Johansen-Berg, H., et al. (2004). Advances in functional and structural MR image analysis and implementation as FSL. Neuroimage 23(Suppl. 1), S208–S219. doi: 10.1016/j.neuroimage.2004.07.051

Stroop, J. R. (1935). Studies of interference in serial verbal reactions. J. Exp. Psychol. 18, 643�. doi: 10.1037/h0054651. doi: 10.1037/h0054651

Veldhuizen, M. G., Bender, G., Constable, R. T., and Small, D. M. (2007). Trying to detect taste in a tasteless solution: modulation of early gustatory cortex by attention to taste. Chem. Senses 32, 569�. doi: 10.1093/chemse/bjm025

Ward, J., and Simner, J. (2003). Lexical-gustatory synaesthesia: linguistic and conceptual factors. Cognition 89, 237�. doi: 10.1016/S0010-0277(03)00122-7

Ward, J., Simner, J., and Auyeung, V. (2005). A comparison of lexical-gustatory and grapheme-colour synaesthesia. Cogn. Neuropsychol. 22, 28�. doi: 10.1080/02643290442000022

Wise, R., Greene, J., B࿌hel, C., and Scott, S. K. (1999). Brain regions involved in articulation. Lancet 353, 1057�. doi: 10.1016/S0140-6736(98)07491-1

Woolrich, M. W., Jbabdi, S., Patenaude, B., Chappell, M., Makni, S., Behrens, T., et al. (2009). Bayesian analysis of neuroimaging data in FSL. Neuroimage 45, S173–S186. doi: 10.1016/j.neuroimage.2008.10.055

Worsley, K. J. (2001). “Statistical analysis of activation images,” in Functional MRI: an Introduction to Methods, eds P. Jezzard, P. M. Matthews, and S. M. Smith (York: Oxford University Press), 251�. doi: 10.1093/acprof:oso/9780192630711.003.0014

Keywords: synesthesia, fMRI, priming, perception, memory, gustation, olfaction

Citation: Colizoli O, Murre JMJ and Rouw R (2013) A taste for words and sounds: a case of lexical-gustatory and sound-gustatory synesthesia. Front. Psychol. 4:775. doi: 10.3389/fpsyg.2013.00775

Received: 27 July 2013 Accepted: 02 October 2013
Published online: 23 October 2013.

Michael Banissy, Goldsmiths University of London, UK

Jürgen Hänggi, University of Zurich, Switzerland
Catherine L. Jones, University of Exeter, UK

Copyright © 2013 Colizoli, Murre and Rouw. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.


Test yourself for synaesthesia

Synesthete.org is a website that has a series of online tests where you can test yourself for synaesthesia – the condition where senses are crossed so, for example, you might be able to taste shapes or see colours associated with specific numbers.

The site is run by the Eagleman Lab at the Baylor College of Medicine who study links between perception and action, as well as the curious world of synaesthesia.

If you’re a researcher, you can also use the site to test and collect results on your own participants, and the same tests are also available as downloadable software for the Matlab package.

It’s now known that synaesthesia is partly inherited, so if you find that you or one of your family members seems to have the condition, others in the family may also have similar abilities.

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General Psychology

Like all of Dr. Ramamchandran's cases this one is by far the most bizarre and interesting. I do not agree that this can condition could be associated with being a product of childhod memories and associations occuring in the brain. The best explanation is clearly that synesthesia is another situation that is best explained in neurologist terms. Neurology helps to explain almost all disorders because the brain is the source and provider of all our information dealing with our emotions and movements. Synesthesia is a result of "mixed sensations: a stimulus in one sensory modality (e.g., hearing) involuntarily elicits a sensation/experience in another modality (e.g. vision). Likewise, perception of a form (e.g., a letter) may induce an unusual perception in the same modality (e.g. a color)"(synesthe.org).

This symptom is very interesting and convinces how human body is formed scientifically. About the brain parts' connection and how they are wired all together then how one parts send signal to stimulate the other parts. I feel sorry about the patients who have this mental disorder but it is very interesting to me as I imagine what's gonna happen if I can manipulate this brain connections. For example, if I can connect my brain parts that govern my vision with a brain parts that govern my smelling sensory parts. Then when smell something I can draw that smell because I can see it. Also as I see something I can smell that view. How exciting would it be.

This was very interesting. Hearing Colors and tasting shapes.. I can't imagine what it feels like.. And this case is also the cause about the brain. Learning of Dr. Ramamchandran's theoris was really new thing and interesting for me.

As someone who has synaesthesia, I should like to correct your belief that we are "patients" with "mental disorders". The condition is in fact not a disorder at all, just a harmless perceptual difference, which many people see as a gift. Some researchers, Ramachandran included, see it as contributing to creativity, and it can certainly aid memory. It's not that weird, either– it now seems it's very common and that many people have it without knowing, since it doesn't usually cause problems and seems perfectly natural if you have it. (Do YOU by any chance often think letters or numbers have colours? You don't have to actually see them– just making the association in your head is enough!)

There is unfortunately a common perception that it's a form of mental illness or something, probably because it's "neurological" and has a long name that sounds a bit like "schizophrenia". Also, media treatment is often very sensational and gives the impression that people's senses are totally messed up so that they can't interpret sensory impressions. This is entirely wrong. Please look up the Wikipedia page on synaesthesia and related links if you don't believe me.

Or you could try these:
http://www.bbc.co.uk/health/conditions/synaesthesia1.shtml
http://www.scholarpedia.org/article/Synesthesia
http://www.naropa.edu/consciousness/synesthesia.cfm
http://www.uksynaesthesia.com/
http://www.syn.sussex.ac.uk/
http://www.maccs.mq.edu.au/research/projects/synaesthesia/index.html
http://med.uth.tmc.edu/comm/alumniMag/2006-Spring/articles/article-03a-brain.html

Authoritative enough for you?

I am not trying to be rude here, but you must understand how unpleasant it is to have people casually assuming there's something wrong with your head!

On the upside– there's no need for you to feel sorry for anyone! This is no more a mental disorder than being left-handed is.

P.S. I'm going to assume you're a nice person and won't come to my blog and harass me for saying this. Just in case you were thinking of it, please don't. I've had a very nasty experience like that, and I don't want a repeat.

I just thought I'd come back and say a few more things about synaesthesia, which is a very misunderstood phenomenon.

Contrary to what people seem to think, it's not like one sense replaces another– you don't hear instead of seeing, or anything weird like that. Also, most people who do this don't actually see the colours physically– that's very rare– they just associate colours with sounds or letters or numbers– L is pale blue, F is green, M is red etc. (However, now and then I have for a moment seen very black or white text as being tinged with "my" colours.)

The only drawback I have ever found to it are that I can get a slight feeling of disquiet from seeing words written in the "wrong" colours, and that I can sometimes get distracted by music and musical tones, just because I start listening to the colours.

It's not harmful, and really not that bizarre. in fact some researchers think just about everyone experiences certain basic forms of synaesthesia, and that it has influenced the development of language and especially metaphor.

(All the above applies to "developmental synaesthesia", the kind thought to be caused by a gene mutation. You can also get it from brain damage, in which case it is a pathological symptom.)


Synesthesia

Synesthesia (also spelled synæsthesia or synaesthesia, plural synesthesiae or synaesthesiae)—from the Ancient Greek σύν (syn), "together," and αἴσθησις (aisthēsis), "sensation" — is a neurologically based phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. People who report such experiences are known as synesthetes.

Synesthesia can occur between nearly any two senses or perceptual modes. Given the large number of forms of synesthesia, researchers have adopted a convention of indicating the type of synesthesia by using the following notation x → y, where x is the "inducer" or trigger experience, and y is the "concurrent" or additional experience. For example, perceiving letters and numbers (collectively called graphemes) as colored would be indicated as grapheme → color synesthesia. Similarly, when synesthetes see colors and movement as a result of hearing musical tones, it would be indicated as tone → (color, movement) synesthesia.

While nearly every logically possible combination of experiences can occur, several types are more common than others.


Grapheme → color synesthesia

How someone with synesthesia might perceive certain letters and numbers.

Another example of real synaesthesia for letters and numbers.

In one of the most common forms of synesthesia, grapheme → color synesthesia, individual letters of the alphabet and numbers (collectively referred to as graphemes), are "shaded" or "tinged" with a color. While synesthetes do not, in general, report the same colors for all letters and numbers, studies of large numbers of synesthetes find that there are some commonalities across letters (e.g., A is likely to be red).


Sound → color synesthesia

In sound → color synesthesia, individuals experience colors in response to tones or other aspects of sounds. Simon Baron-Cohen and his colleagues break this type of synesthesia into two categories, which they call "narrow band" and "broad band" sound → color synesthesia. In narrow band sound → color synesthesia (often called music → color synesthesia), musical stimuli (e.g., timbre or key) will elicit specific color experiences, such that a particular note will always elicit red, or harps will always elicit the experience of seeing a golden color. In broadband sound → color synesthesia, on the other hand, a variety of environmental sounds, like an alarm clock or a door closing, may also elicit visual experiences.

Color changes in response to different aspects of sound stimuli may involve more than just the hue of the color. Any dimension of color experience (see HSL color space) can vary. Brightness (the amount of white in a color as brightness is removed from red, for example, it fades into a brown and finally to black), saturation (the intensity of the color fire engine red and medium blue are highly saturated, while grays, white, and black are all unsaturated), and hue may all be affected to varying degrees.[26] Additionally, music → color synesthetes, unlike grapheme → color synesthetes, often report that the colors move, or stream into and out of their field of view.

Like grapheme → color synesthesia, there is rarely agreement among music → color synesthetes that a given tone will be a certain color. However, when larger samples are studied, consistent trends can be found, such that higher pitched notes are experienced as being more brightly colored.[19] The presence of similar patterns of pitch-brightness matching in non-synesthetic subjects suggests that this form of synesthesia shares mechanisms with non-synesthetes.[19]


Number form synesthesia

A number form is a mental map of numbers, which automatically and involuntarily appears whenever someone who experiences number-forms thinks of numbers. Number forms were first documented and named by Francis Galton in "The Visions of Sane Persons". Later research has identified them as a type of synesthesia. In particular, it has been suggested that number-forms are a result of "cross-activation" between regions of the parietal lobe that are involved in numerical cognition and spatial cognition. In addition to its interest as a form of synesthesia, researchers in numerical cognition have begun to explore this form of synesthesia for the insights that it may provide into the neural mechanisms of numerical-spatial associations present unconsciously in everyone.


Ordinal-linguistic personification (OLP, or personification for short) is a form of synesthesia in which ordered sequences, such as ordinal numbers, days, months and letters are associated with personalities. Although this form of synesthesia was documented as early as the 1890s modern research has, until recently, paid little attention to this form.

For some people in addition to numbers and other ordinal sequences, objects are sometimes imbued with a sense of personality, sometimes referred to as a type of animism. This type of synesthesia is harder to distinguish from non-synesthetic associations. However, recent research has begun to show that this form of synesthesia co-varies with other forms of synesthesia, and is consistent and automatic, as required to be counted as a form of synesthesia.


Lexical → gustatory synesthesia

In a rare form of synesthesia, lexical → gustatory synesthesia, individual words and phonemes of spoken language evoke the sensations of taste in the mouth.

Jamie Ward and Julia Simner have extensively studied this form of synesthesia, and have found that the synesthetic associations are constrained by early food experiences. For example, James Wannerton has no synesthetic experiences of coffee or curry, even though he consumes them regularly as an adult. Conversely, he tastes certain breakfast cereals and candies that are no longer sold.

Additionally, these early food experiences are often paired with tastes based on the phonemes in the name of the word (e.g., /I/, /n/ and /s/ trigger James Wannerton’s taste of mince) although others have less obvious roots (e.g., /f/ triggers sherbet). To show that phonemes, rather than graphemes are the critical triggers of tastes, Ward and Simner showed that, for James Wannerton, the taste of egg is associated to the phoneme /k/, whether spelled with a "c" (e.g., accept), "k" (e.g., York), "ck" (e.g., chuck) or "x" (e.g., fax). Another source of tastes comes from semantic influences, so that food names tend to taste of the food they match, and the word "blue" tastes "inky."

Do you have it or know someone who does? What are your experiences with it?

If you have any questions about the condition itself or other's experiences, please add them to the conversation as well. I know I will.

I myself have only slightly expressed synesthesia, and hadn't realized not everyone saw words the way I did until the last year or so. As such, I'm curious about the experiences of others.


What It's Like To Experience Synesthesia: The Taste Of Music And Colors Of Language

Synesthesia is an involuntary and consistent joining of two different senses. What's it like to possess this unusual gift of perception? Photo courtesy of Shutterstock.

Synesthesia is an involuntary joining of two different senses. A person might see the color red, for example, whenever they hear a bell ring. Or, the sound of music played on a piano might evoke the taste of coffee for another. An important aspect of synesthesia is consistency — the linked perception is the same every time so that the number "5" will always be red, while the number "2" will always be green.

What is it like to experience synesthesia? A common theme in stories from synesthetes is the moment they discover they are different. "I nodded meekly but inside, I was reeling," wrote one synesthete when he first discovered others did not perceive the world as he did. "No colors? Everyone lived in a white word where numbers and letters were simply black? And music didn’t fill the air with sparkles and waves of colored light? Did that mean they didn’t see auras around people either? Their worlds were colorless?"

It's also important to understand synesthetes do not regard the additional perception as imaginary — the experience of a blend of senses is just as vivid and real as a single sense is for others. Just as you would not doubt you are seeing red, for instance, a synesthete does not doubt that a song by Sonic Youth is pale yellow. The pairing of senses, individual and varied though they may be, are not infinite just as the senses are not infinite. Some researchers estimate records of 35 or so different subtypes, such as taste-hearing (hearing a sound produces a taste) and sound-touch (feeling an object produces a sound). The most common are color-graphemic, in which number, letters, and/or shapes produce colors (or sometimes simple patterns) and color-auditory, in which voices, music, and/or random noise produces colors, textures, and shapes.

Should synesthetes consider themselves lucky?

Many do, though sometimes they may feel isolated and worry about what others will think. “The oddest thing about all this is that I thought this was how everyone perceived the world until about 8th grade when I asked a childhood friend about how he liked the purple tone a certain song had and he looked at me like I had 4 heads,” wrote a male synesthete. “I had something similar happen in a college music room where I was tired and not thinking and the teacher asked what I thought of a particular piece and I blurted out ‘I hate it it is too pale yellow’ which of course caused half the room (including the teacher) to freak out or just start laughing.”

Disharmony may sometimes bother other synesthetes, who prefer the regularity of their own visions. Seeing a poster with the numbers in color, for instance, one synesthete commented, “If a 4 is purple instead of green it makes me mad.” A synesthete who tastes language said, “I taste the words whether I read them in a book or hear them in a conversation. The downside of this is when I am eating something and the taste of the word spoken does not go very well with the taste of whatever I am eating.”

One synesthete who routinely sees colors when she hears music also reports a more abstract linking between personality and color: “This is good, it helps me choose good friends,” she notes, adding “purple people are snobbish.”

Friendship is a necessary requirement for confidence with many who possess this unusual ability. “I usually don't share with many people because it takes way too much time to explain,” wrote another synesthete. Yet he also strongly believes this trait is a gift. “I could not imagine a life without it.”

Synesthesia occurs in about four percent of the population. In particular, women have greater odds of being born with the condition in the U.S., studies show that three times as many women as men, while in the UK, the ratio is six to one. This difference in prevalance may be tied to the fact that the condition also runs in families. For this reason, researchers believe there is a genetic component even though the specific genes underlying synesthesia are still unknown. Oddly, synesthetes are more likely to be left-handed than the general population.

Neuroimaging studies show that there are unusual connections in the brains of synesthetes regions not usually wired together are linked and this is what causes a sensation along one channel to automatically trigger a perception in another. A recent study found that there is a link between synesthesia and autism spectrum conditions. Autism occurs in one percent of the population. Yet when researchers tested 164 adults with autism and 97 adults without the condition, synesthesia occurred in nearly one in every five people (20 percent) with autism — much greater than the four percent found in the population at large. The similarities between the two conditions are striking as with synesthesia, neuroimaging studies have also discovered greater connectivity in the brains of people with autism as compared to those without the condition.


The complex study of synesthetes (otherwise known as the story of how I fell down the internet rabbit hole)

This post is brought to you by a long line of google searches, links to other articles and me getting distracted by yet another cool fact and then not being able to decide how to focus this post into a reasonable length. Initially, I planned to write about synesthesia (i.e. a really cool phenomenon that I’ll explain soon but which essentially causes people to have unusual overlapping sensory experiences) and how it relates to other disorders and phenomenons linked to neuroplasticity and incorrect wiring of the brain. But then, during my research, I found an article discussing how advertisers use “culturally synesthetic” associations (the associations between various sensory stimuli (for examples, colors and flavors) that are largely common across all individuals in a society) to influence our perceptions and feelings about their products. Then, because this didn’t sound like enough neurobiology for me, I started looking up the theories behind how synesthesia actually occurs in the brain, and somehow came across the phenomenon of mirror-touch synesthesia in which a person observes another person touching something or being touched and feels like they themselves are also being touched which was super interesting and has a lot of implications for our understanding of empathy, consciousness, and the brain.

I got distracted once again and found a list on Wikipedia of all the famous people who are believed to have/have had synesthesia (the list overwhelmingly consists of artists, musicians, and composers, and includes Kanye West, Marilyn Monroe, Van Gogh, and Hans Zimmer). This got me to think about the ways in which you can use psychology and knowledge about perception to create tests that can be used to determine whether someone is an actual synesthete or not.

By this point (with 20+ tabs open and still no real focus) I realized I had found far too many sources and topics to be condensed into a single post. Long story short, what I’ve learned is that there are just too many cool things to study and learn about synesthesia that it is impossible to cover everything in a post that anyone would actually want to read in its entirety, so I’ve decided to force myself to focus on just one thing: current scientific theories about how synesthesia comes to occur in the brain (since this is supposed to be a blog about neuroscience). (Don’t worry, I’ll link all the cool articles I found at the bottom in case anyone is interested in learning more!)

First, I’ll start off by better explaining what synesthesia is and the many different ways in which it manifests. Synesthesia is a condition that causes involuntary ‘blending’ of the senses. Essentially, this means that when a synesthete experiences a particular sensory input, another experience occurs alongside in a different sense. For example, some synesthetes experience a taste in their mouth when they hear a given word, or see shapes, movement and colors when they detect certain smells. There are about as many ways in which synesthesia can manifest as there are ways to pair any sense with another (some estimates suggest as many as 80 variations). However, some forms, such as grapheme-color (letters have different color associations), chromesthesia (sounds cause colors to be experienced), and special sequence synesthesia (seeing numerical sequences such as dates or months as points in space around them) are much more common than others. Synesthesia is estimated to occur in 3.7% of the general population, although it is likely that this number is higher due to the fact that many people don’t realize they have it until someone convinces them that, for instance, other people don’t usually see a specific color when they think of each letter.

As synesthesia is a very personal and individual experience and can be difficult to observe in another person (although it is important to note that sometimes the associations can be so overwhelming and intrusive that it can be difficult for some synesthetes to function normally, especially in highly stimulating environments such as crowds or public spaces), it may leave you wondering how you could ever prove that someone does or does not have synesthesia after all, couldn’t they just have memorized a color for each letter and be faking it? How can you determine that the associations are actually involuntary and consistent across time? There are a variety of tests that use existing knowledge about perception to test whether the person is actually having a perceptual experience or not.

Source: synesthesiatest.org

For example, a common test for grapheme-color synesthesia is to present a person with a picture full of several black numbers or letters, which consist of mostly one number with a few instances of another number randomly sprinkled in (see picture to the left). A person without synesthesia sees a bunch of black shapes and has difficulty picking out which numbers are different from the rest, but a person with synesthesia will automatically associate colors with the numbers and thus will be able to quickly pick out the numbers that are ‘different colored’ (see picture to the right). This test can be effective for diagnosing people who have very strong synesthetic associations between letters/numbers and colors, but I don’t think it is necessarily as effective for people who sort of just ‘feel like’ a certain letter is supposed to be a certain color. Other more abstract forms of synesthesia such as sound-color or touch-flavor are more difficult to definitively prove, but another common method that is used to test for many types of synesthesia is to have a person report their synesthetic associations and then retest them again later to see if they are able to report the same associations. For example, in 1987, a group of researchers tested a word-color synesthete by asking her to describe the color that 100 random words triggered. A year later they randomly tested her again and she was able to report the same associations with 90% accuracy, while a group of non-synesthetic controls performing the same tests only two weeks apart only showed 20% consistency.

Ok, now that I have convinced you that synesthesia is real and can be scientifically verified in a variety of ways, you might be wondering about the underlying neurobiology of it all. The first insights came when Paulesu et al. (1995) used positron-emission tomography (a method of imaging brain activity), to show that word-color synesthetes, when presented with auditory words but not when presented with pure tones, exhibited activation in various regions of the brain not active in non-synesthetes doing this task. These regions included many involved in integration of color with shape and in verbal tasks which require attention to visual features of objects to which words refer, but notably did not include lower visual processing areas. This suggests a measurable, underlying neurobiological difference in the brains of synesthetes.

Despite evidence that it has a biological cause, there is still no definitive understanding of how synesthesia originates in the brain. There are countless theories, some involving genetics, increased myelination in certain axons (essentially causing signals in the brain to travel faster and more easily across various regions), or more molecular factors affecting inhibitory processes in some neuronal pathways, which results in those signals passing backwards from multisensory areas to single-sensory areas in a way that they are not normally allowed to. Research has shown that some types of synesthesia are associated with genetic factors, even locating specific regions of DNA that might be implicated in colored sequence synesthesia. Other research suggests that, more specifically, a genetically driven overabundance of neural connections in the brain leading to unusual wiring between multiple sensory areas might be the cause.

While there is still much we don’t understand, what we do know is that synesthesia is an extremely complex and fascinating phenomenon, the study of which has implications for a broad array of other areas of neuroscience including perception, consciousness, the effects of psychedelic drugs, disorders like schizophrenia, learning and memory, the list goes on and on. Further research is needed in order to more fully understand synesthesia, but maybe we can one day unlock the secrets to its development so that everyone can experience it. Wouldn’t you like to see beautiful colors or taste chocolate when you listen to your favorite song?


Synesthesia allows authors to deliver another level of description in literature. It challenges readers to think out of the box and reinterpret their senses as they know them. Most importantly, though, synesthesia is a unique device that very few authors employ, making it quite notable and distinctive when an author does use it.

Example 1

The beloved children’s fantasy novel The Phantom Tollbooth is rich with descriptions that use synesthesia. The author Norton Juster is a synesthete, and he used his own sensory perceptions to inspire parts of the book, as you can see in the following passage from Chapter 10: A Colorful Symphony:

“I don’t hear any music,” said Milo.
“That’s right,” said Alec “you don’t listen to this concert—you watch it. Now, pay attention.”
As the conductor waved his arms, he molded the air like handfuls of soft clay, and the musicians carefully followed his every direction.
“What are they playing?” asked Tock, looking up inquisitively at Alec.
“The sunset, of course. They play it every evening about this time.”
“They do?” said Milo quizzically.
“Naturally,” answered Alec “and they also play morning, noon and night, when, of course, it’s morning, noon and night. Why, there wouldn’t be any color in the world unless they played it.”

Here, Juster uses synesthesia in the book’s fantasy world to express the idea of a connection between music and colors. Alec explains that the sunset they see every day is actually created by instruments that play colors instead of musical notes. He also tells Milo to “watch” the concert, rather than listen to it, because the instruments will create the colors of the sunset and all of the colors in the world.

Example 2

In Inferno of the epic poem The Divine Comedy, Dante uses synesthesia to emphasize a place’s harshness:

E’en such made me that beast withouten peace,
Which, coming on against me by degrees
Thrust me back thither where the sun is silent.

Here, Dante refers to a place “where the sun is silent.” Our perception of the sun is usually associated with our sense of sight (its brightness) and touch (its heat), but not with any sort of sound. By asserting that the sun is silent, Dante is highlighting the fact that it is absent from the place he is describing. His description has a greater impact than “the sun can’t be seen” or “there is no heat”—“silent” suggests a dark, lifeless, cold and colorless place that never sees the sun.


Mirror-Touch Synesthesia: Pain & Empathy

If you’ve ever accompanied a friend or family member on a doctor’s visit and sat in the very room the checkup ritual took place, you’ve likely had the fortune of empathizing with that friend or family member, watching as the stethoscope was pressed to the bare back, the reflex hammer hit the knee, or the vaccination needle penetrated flesh. Now, for a second (and no longer), imagine that, in watching these actions take place, you also felt them. A tingle on your back. A knock to your knee. A pinch on your skin. That is mirror-touch synesthesia.


Can Synesthesia Be Learned?

In class this week, we have been very curious about the origins of synesthesia. Synesthesia is a condition in which sensory experiences evoke other perceptual experiences that are not typically elicited in most individuals. A common example is seen in individuals who associate specific colors with certain letters or graphemes. We have been asking many questions, including: How much of synesthesia is genetic? How much is dependent on our environment? Is it dependent on exposure to certain features in our culture, possibly during a “critical period”? For example, could a person develop sound to color synesthesia with a limited exposure to sound in childhood?

A study conducted by Bor, Rothen, Schwartzman, Clayton, and Seth (2014) investigated whether or not adults without synesthesia could be trained to acquire these synesthetic experiences. These non-synesthetes were trained to learn 13 specific letter-color associations by engaging in various memory and reading tasks over the course of 9 weeks. After training, participants took a variety of tests used to measure genuine synesthesia, like the color consistency task, the synthetic Stroop task, and a classical conditioning test—and they all “passed” as actually having synesthesia! Days after training, participants showed behavioral and physiological evidence for synesthesia, reporting perceived color experiences for colorless letters. Furthermore, participants were experiencing these strong perceptions inside and outside of the lab setting and across different contexts.

However, participants gained more than these perceptions. Bor et al. (2014) also found that participants who completed training showed an increase in their IQ by an average of 12 points, compared to controls. This suggests that there is something about learning synesthetic links that can result in an enhanced cognitive ability. These results are useful and exciting to explore. It is possible that this training could help individuals at risk for dementia or other diseases that cause cognitive decline.

In Bor et al.’s study (2014), the training was intense and lasted over a period of 9 weeks. However, the researchers note that some participants demonstrated synesthesia after just 5 weeks! So, it seems that there are some aspects of synesthesia that can be learned. The “genuineness” of their synesthesia, however, is under debate. In most participants, this ability faded away over time. This study made me wonder, what else could we learn if we are committed to this sort of training? For example, could we learn other special skills that are present in conditions like Savant Syndrome?

Bor, D., Rothen, N., Schwartzman, D., Clayton, S., & Seth, A. (2014). Adults Can Be Trained to Acquire Synesthetic Experiences. Scientific Reports, 4. doi: 10.1038/srep07089



Comments:

  1. Dinos

    I hope that the second part will be no worse than the first

  2. Wanjala

    Between us say, you should try to look at google.com

  3. Lauriano

    It's a shame I can't speak now - I'm rushing to work. I will be set free - I will definitely speak my mind.

  4. Akisho

    NOT heard of that



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