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The Synesthesia Project

Welcome to the Synesthesia Project site. On these pages, you will find more information about synesthesia. Although the Synesthesia Project is no longer active at Boston University, Dr. Veronica Gross is still working to explore memory, perception, and synesthesia. She is happy to talk with synesthetes, students, and other researchers about synesthesia and her research.

Frequently Asked Questions about Synesthesia

This FAQ written by Dr. Veronica Gross.

1) What is synesthesia?
2) What are the characteristics of synesthesia?
3) What sorts of synesthesia exist?
4) How common is synesthesia?
5) What are synesthetes like?
6) Is synesthesia a disease?
7) Is there any proof that synesthesia occurs?
8) Does synesthesia get in the way of everyday life?
9) I'm interested in synesthesia. Where can I get more information?
10) I think I might have synesthesia. Who can I contact?

What is synesthesia?

Synesthesia (or synaesthesia) is loosely defined as "senses coming together," which is just a translation of the Greek (etymology: syn - together, esthesia from aesthesis - sensation). At its simplest level, synesthesia means that when a certain sense or part of a sense is activated, another unrelated sense or part of a sense is activated concurrently. For example, when someone hears a sound, he or she immediately sees a color or shape in his or her "mind's eye." People that have synesthesia are called synesthetes. Back to top of FAQ

What are the characteristics of synesthesia?

Synesthesia is both involuntary but elicited (Cytowic, 1996) and irrepressible. That means, the synesthete does not have to trigger the second sensory experience consciously; it happens on its own as a response to a stimuli, i.e. it is also elicited. This also means that the synesthete cannot control when the synesthesia happens or to what stimulus in a certain sensory modality (touch, taste, etc) the synesthete will respond. Synesthesia is also very stable. The associations between letters and colors in color-graphemic synesthesia, for example, are formed very early and do not change over time. A synesthete tested on his or her associations will give the same answers 70%-100% over a period of weeks, even years! Compare this with an average performance of around 20-40% by controls trained to remember similar associations.

One might ask, "Well, how is this different from my smelling some pie and then seeing a picture of pie in my mind?" The answer is, very different! When you experience a smell and then see a picture, you are using your memory to access a pre-formed picture of a pie. However, this picture may not be the same every time you smell a pie, nor will the picture of the pie appear every time you pick up the smell. On the other hand, a synesthete who had visualization-smell synesthesia would have the same experience every time. Their mental picture, though, would not be of a pie or anything so complex, but of unrelated textures and colors. If you smelled something new, such as a food you'd never encountered before, you would not have a picture to go along with it. A synesthete, though, would automatically have a new set of textures and colors assigned to this new experience. Also, the synesthete would have the experience regardless of whether he or she were paying attention to the smell, whereas someone without synesthesia does not usually have memory percepts or experiences associated with unattended stimuli. Back to top of FAQ

What sorts of synesthesia exist?

In theory, there can be as many types of synesthesia as there are sensory modality pairings. Some estimate upwards of thirty-five or so different subtypes, such as taste-hearing (hearing a sound produces a taste) and sound-touch (feeling an object produces a sound). Some of these subtypes, however, are far more common than the others. The most common subtypes are color-graphemic, in which letters and/or numbers (and occasionally shapes), produce colors and simple patterns, and color-auditory, in which auditory input, including voices, music, and random noise, produces colors, textures, and shapes. Within these broad categories are many permutations, from those who only experience color in digits to those who have vibrant associations with whole words. For more information on the type and frequency of synesthesia, please see Sean Day's Synesthesia website, which contains his own documentation of synesthetic phenomena.

The synesthetic percepts (what the synesthete experiences as the result of another stimulus) are as varied as the synesthetes themselves. Some see just flat colors, while others may see complex patterns in three dimensions, while still others may taste extremely particular things, food and non-food alike. In color-graphemic, it is important to note that the synesthetic percept may appear in the mind's eye or outside in the visual field, contrary to prior assertions.(Palesceu) Back to top of FAQ

How common is synesthesia?

The short answer is that no one really knows. The long answer is anywhere from one in every 100,000 people to one in every 5,000 people, but it's difficult to get a good count because of the nature of synesthesia. More on this below. The number of cases seems to be increasing, but whether this is due to an actual increase in synesthetes or an increase in self-reports generated by greater public awareness and scientific interest cannot be determined. Back to top of FAQ

What are synesthetes like?

There is once again a short answer and a long answer. The short answer is that we're not really sure, but we have some good leads. The long answer is we're not sure and that our leads may be wrong.

First, what we do know or what we think we know. All "true" synesthetes have had their synesthesia from a young age, with their earliest memories as from as young of an age as two or three. Synesthetes are more often female, by a rough figure of almost two to one. Synesthetes tend to have other family members, usually female, with synesthesia, suggesting a potential genetic component. Synesthetes tend to be more artistic, or drawn towards more creative and/or artistic professions and hobbies. They usually perform higher on cognitive assessment tests such as the WAIS-R, higher on memory tests such as the CVLT, but lower on tests of spatial function. There is a preponderance of English-speaking Caucasians, but this is most likely a sampling bias and probably not representative of actual numbers.

Here is the long answer as to why our numbers are imprecise. When someone has a disease that causes a loss of function, such as a particular type of nerve degeneration or a certain variety of colon cancer, he or she will know that something is wrong and probably go to a doctor for treatment. When a child is born with an obvious or eventually obvious congenital defect, the family may turn to a hospital for advice. Such treatment generates lists of patient information related to age, race, sex, economic status, native language, familial prevelence, and so on. Doctors may compile statistics on this information, as well as the frequency of the disorder in the region. From all this data, a profile of the average patient may be generated and the epidemiology of the disease tracked.

Synesthetes, on the other hand, do not know that anything is "wrong." They recognize their synesthesia early in life but without external input, they will not realize that what they are experiencing (colors, tastes, sensations) is unique. In the eyes of a color-graphemic synesthete, her synesthetic percepts are shared by the whole world. When the synesthete does recognize that he or she is doing something unusual, he or she may be reluctant to discuss what's going on for fear of being labeled a freak, shunned, misunderstood, accused of lying, or even diagnosed with a mental illness. It is common for a synesthete to remain silent about his or her synesthesia for decades until a magazine article or radio program makes the synesthete realize that she's not alone and he's not crazy. For these reasons, getting reliable statistics on synesthesia is very difficult. Those with access to articles and with an understanding of research, usually middle-class and better educated, are more likely to participate in studies, skewing the population. That most recruiting is done in or around university campuses is also a major bias towards a certain subject pool. Until more research is done in the community as a whole, the understanding of the synesthetic profile will remain sketchy. Back to top of FAQ

Is synesthesia a disease?

No, synesthesia is not a disease. In fact, several researchers have shown that synesthetes can perform better on certain tests of memory and intelligence. Synesthetes as a group are not mentally ill. They test negative on scales that check for schizophrenia, psychosis, delusions, and other disorders.

It is important to note here that certain synesthesias may be induced by the loss of a limb. Remapping of the cortex after an amputation results in the phenomenon known as a phantom limb or phantom sensation. These are more correctly called parathesias. They differentiate from synesthesia in that they are not present from birth and they may occur without being evoked. Ramachandran has done remarkable work with these patients in relieving phantom limb pain.

Finally, synesthesia is not the result of intense drug use. While those who take psychotropic drugs such as LSD or MDMA may experience synesthetic-like experiences, these experiences are extinguished by the discontinuation of the high and do not persist during sober periods. Back to top of FAQ

Is there any proof that synesthesia occurs?

Numerous imaging and behavioral studies have been conducted showing signficant evidence of synesthesia. These include, but are not limited to, fMRI showing activation of V2/V4 during the presentation of auditory stimuli to a color-sound synesthetes; strooping of congruent/incongruent colored words for color-graphemic synesthetes; "pop-out" effects in a color-digit synesthete whose synesthetic colors appeared on the digits themselves; and of course the test of genuineness itself. More information about these articles will appear here in the following weeks. Back to top of FAQ

Does synesthesia get in the way of everyday life?

Many people think that it must be very confusing and distracting for a synesthete to walk around all day with these colors, shapes, and sensations bombarding them. The truth is that they find their synesthesia enjoyable and not a hindrance to normal life. In fact, they pity non-synesthetes for having what the synesthetes consider one-dimensional sensory experiences.

To understand this better, think of a deaf person with new cochlear implants. He or she may find the constant rush of sounds, from crashing trash cans to the ticking of a clock, disorienting and difficult to process. However, save the occasional loud sound, those hearing since birth have little problem tuning out extraneous noise. Similarly, synesthetes have long since grown accustomed to their synesthesia and the extra experiences are not distracting for the most part. Just as a firecracker would startle a hearing person, though, a sudden bright light triggered by a loud sound may startle a synesthete.

The only time a synesthete is bothered by his or her synesthesia is when a stimulus produces an adversive synesthetic experience. Some words may taste like cigarrette smoke or sour milk to a taste-sound synesthete, while a color-graphemic synesthete may dislike some letters because they have ugly colors. For some color-graphemics, it is disturbing to find people whose names produce colors incongruent with their personalities; for example, a boring person whose name has a vibrant, exciting hue. These likes and dislikes may produce certain idiosyncracies of behavior, such as the naming of children, but nothing more peculiar than those of any other person. Back to top of FAQ

I'm interested in synesthesia. Where can I get more information?

There are many interesting books and articles about synesthesia. However, several are outstanding for their bredth and ease of reading.

The most popular are The Man Who Tasted Shapes by Richard Cytowic and Synesthesia: Classic and Contemporary Readings by John Harrison, Simon Baron-Cohen, and Ian McDonald. The first book provides an extensive case history of a taste-touch synesthete. While it is less scientific than the second, it is nonetheless and engaging and interesting read. The second book, as the name suggests, is a collection of papers from the last one hundred years on the nature and expression of synesthesia. More articles and books will be added in the near future. You also may email Veronica Gross, the graduate student on the project. Back to top of FAQ

I think I might have synesthesia. Who can I contact?

If you are interested in participating in our research studies or just want to learn more, you may contact Dr. Veronica Gross. Back to top of FAQ


Please note that we do not maintain or endorse any of the links found underneath, nor do we vouch for the correctness of the information found therein. These are links I found interesting and think visitors would enjoy or find informative.

The Synesthesia Battery is maintained by the lab of David Eagleman. The site offers a chance for synesthetes to answer questions about their synesthesia. Color-graphemic synesthetes may also participate in a letter/word/number-->color matching task as part of the battery.

Sean Day's Synesthesia webite, a collection of links, research, and essays by synesthete and researcher Sean Day. Also contains links to the Synesthesia List.

Museums of the Mind. An extremely complete listing of synesthesia sites on the web, including interviews, articles, artwork, and research links.

Mixed Signals is a for synesthetes-by synesthetes website. It includes links to a variety of ongoing research projects, as well as forums for discussing synesthesia.

American Synesthesia Association - Homepage of the ASA, a group of synesthetes and synesthesia researchers who aim to educate the public about synesthesia and conduct experimental investigations to further our understanding of this phenomenon. Contains information about the yearly ASA meeting.

International Synesthesia Association - Homepage of the ISA, a UK-based group of synesthetes and researchers dedicated to learning more about synesthesia.

Synesthesia Webring. A list of 24+ sites, some active and some not, about synesthesia. Some are professional sites while others are the personal sites of individual synesthetes.

Synesthesia and the Synesthetic Experience. An MIT-based site dealing with synesthesia. It hasn't been updated in a while and some links are broken, but there are working areas of the site, to include synesthete interviews.

Synesthesia links and articles is a list of articles and links from a taste-name synesthete's personal homepage.

Synesthesia - the mixting of the senses is a computational look at synesthesia.

Synesthesia: Phenomenology And Neuropsychology. A 1995 article by Richard Cytowic published in the Psyche journal. Out of date, but still informative.

Broken link? Questions? Accolades? Email me.


The Synesthesia FAQ

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