A&O READING – excerpts about synesthesia


excerpts about synesthesia





































What is synesthesia?  — 

J. Weinstock, South Milwaukee, Wis., posted on June 17, 2002

Thomas J. Palmeri, Randolph B. Blake and René Marois of the psychology department and the Center for Integrative and Cognitive Neuroscience at Vanderbilt University study synesthesia. They provide the following explanation:

When you eat chicken, does it feel pointy or round? Is a week shaped like a tipped-over D with the days arranged counterclockwise? Does the note B taste like horseradish? Do you get confused about appointments because Tuesday and Thursday have the same color? Do you go to the wrong train station in New York City because Grand Central has the same color as the 42nd Street address of Penn Station? When you read a newspaper or listen to someone speaking do you see a rainbow of colors? If so, you might have synesthesia.

Synesthesia is an anomalous blending of the senses in which the stimulation of one modality simultaneously produces sensation in a different modality. Synesthetes hear colors, feel sounds and taste shapes. What makes synesthesia different from drug-induced hallucinations is that synesthetic sensations are highly consistent: for particular synesthetes, the note F is always a reddish shade of rust, a 3 is always pink or truck is always blue.

The estimated occurrence of synesthesia ranges from rarer than one in 20,000 to as prevalent as one in 200. Of the various manifestations of synesthesia, the most common involves seeing monochromatic letters, digits and words in unique colors—this is called grapheme-color synesthesia. One rather striking observation is that such synesthetes all seem to experience very different colors for the same graphemic cues. Different synesthetes may see 3 in yellow, pink or red. Such synesthetic colors are not elicited by meaning, because 2 may be orange but two is blue and 7 may be red but seven is green. Even more perplexing is that synesthetes typically report seeing both the color the character is printed in as well as their synesthetic color. For example, is both blue (real color) and light green (synesthetic color).

Synesthetes report having unusually good memory for things such as phone numbers, security codes and polysyllabic anatomical terminology because digits, letters and syllables take on such a unique panoply of colors. But synesthetes also report making computational errors because 6 and 8 have the same color and claim to prejudge couples they meet because the colors of their first names clash so hideously.

For too long, synesthetes were dismissed as having overactive imaginations, confusing memories for perceptions or taking metaphorical speech far too literally. Recent research, however, has documented the reality of synesthesia and is beginning to make headway into understanding what might cause such unusual perceptions.

Research has documented that synesthetic colors are perceived in much the same way that nonsynesthetic individuals perceive real colors. Thus, synesthetic color differences can facilitate performance on tasks in which real color differences facilitate performance for nonsynesthetes and can impair performance on tasks in which real color differences impair performance for nonsynesthetes.

In one such task, people are asked to say the color of the ink a word is printed in as quickly as possible (for example, responding “pink” to and “blue” to ). For lexical synesthetes, these words take on unique colors. When the synesthetic color matches the ink color, responses are fast. But when the synesthetic color mismatches the ink color, responses are slow, presumably because subjects need to resolve the conflict over which color name to respond with. Although such results demonstrate that synesthesia is automatic, in the sense that they cannot turn off their synesthesic experience even when it interferes with a task, these results do not reveal whether synesthetic colors are perceptions or memories.

To demonstrate the perceptual reality of synesthetic colors, researchers have introduced synesthetic color differences into a variety of traditional visual-perception tasks. Searching for a among ’s is a difficult task because the digits are so visually similar, differing by only a mirror reflection. If the was colored orange and the ’s were colored green, the search task would be trivially easy because the orange digit visually pops out from the background of green digits. When shown a display consisting of monochromatic digits, we found that a synesthete could quickly find the target because for him was orange but was green (see image).

Vilayanur Ramachandran and Edward M. Hubbard of the University of California at San Diego, have reported complementary findings supporting the perceptual reality of synesthetic colors. In one task, they presented synesthetes with an array of equally-spaced letters and digits. Synesthetes reported that these arrays organized themselves into distinct rows or columns depending on whether the rows or columns of characters were the same synesthetic color. This perceptual grouping based on synesthetic color is analogous to the kind of perceptual grouping non-synesthetes experience with real colors.

Claims for the perceptual reality of synesthetic colors have been bolstered by recent functional brain imaging studies by researchers in the U. K. showing that synesthetic color activates central visual areas of the brain thought to be involved in perceiving real colors.

The neural mechanism by which synesthetic colors are automatically bound to alphanumeric characters remains a mystery. One possibility is that synesthesia might arise from some kind of anomalous cross-wiring between brain areas that are normally segregated in nonsynesthetic individuals. For grapheme-color synesthesia, there may be cross-wiring between digit and letter processing areas and color processing areas in the visual cortex, which occupy neighboring regions of the human brain.

The causes of synesthesia also remain unknown. Some scientists have suggested that everyone is born synesthetic but that the typical developmental trajectory results in these highly interconnected brain areas becoming far more segregated. We do not know why synesthetes retain some of these anomalous connections. A biological determinant may be partially at work in certain cases of synesthesia, because the condition tends to run in families; moreover, nearly six times as many women as men report synesthesia. Whatever its etiology, synesthesia provides cognitive neuroscientists with a unique opportunity to learn more about how the brain creates our perceptual reality.


.© 1996-2003 Scientific American, Inc. All rights reserved.


From Scientific American site,















































































from the March 24, 2005 edition – http://www.csmonitor.com/2005/0324/p17s01-stgn.html

A musician who tastes each chord – literally

By Robert C. Cowen

When you listen to music, what does it taste like? That’s not a silly question. Swiss researchers are studying a young musician who consistently identifies musical intervals by the flavors they induce on her tongue.

For example, a minor second is sour. A major second is bitter. A perfect fourth is mown grass. A minor sixth is cream. An octave has no taste at all. Neuroscientists call such mixed perception synaesthesia. It’s a nagging reminder that what we perceive is not just a simple processing of stimuli from one or another of our senses.

The effect can be startling, as my wife and I learned one night while sleeping with the windows open. A loud crack of thunder brought us bolt upright. Had lightning hit the house? Not quite. We had “heard” a “loud” stench. A skunk had let go outside.

The most common type of synaesthesia is the concurrence of color with a sound, taste, or scent. The musician taking part in the research at the University of Zurich experiences this. She sees C as red and F-sharp as violet. But in reporting their study in Nature, Gian Beeli, Michaela Esslen, and Lutz Jäncke note that it is her rare ability to taste musical intervals that stands out. Calling her E.S. to protect her privacy, they say this is the first such case to be reported.

The researchers say that, after extensive systematic testing, “we found that E.S.’s tone-interval identification was perfect.”

The case differs from a more holistic type of sound/taste synaesthesia in which the flavor of an entire meal may pair with a musical tone, they add. E.S.’s ability to accurately relate musical intervals with specific tastes gives her an edge in the difficult task of interval identification.

The Swiss team notes that this raises the intriguing possibility “that synaesthesias may be used to solve cognitive problems” such as figuring out these musical intervals. This amusing perceptional tic may have practical value that would encourage evolution to favor its development. Studying it helps neuroscientists in their larger task of trying to understand how our cognitive system works as a whole.

Probing our ability to make and appreciate music is on the cutting edge of that research. Art and culture “must have their origin in the function and structure of the human nervous system,” explains Robert Zatorre, a neuroscientist at the Montreal Neurological Institute in Canada, in the current issue of Nature.He adds that “listening to and producing music involves a tantalizing mix of practically every human cognitive function.”

Our musical proclivities have deep roots. New babies show appreciation of music and recognize tones and tunes. Singing, dancing, and tapping feet to snappy rhythms are common skills. Organizing words into meaningful sentences looks a lot like organizing notes into musically meaningful sequences. Are language ability and musical ability linked? Dr. Zatorre asks. “Maybe music … manages to transcend mere perception precisely because it contacts our more primordial neurobiology,” he adds.

Those who prefer a classical symphony to a rap concert on the street – and the rappers also – should realize this possibility. Whatever their musical taste, humans share a common neurobiological ability to enjoy rhythm and melody. Those who can perceive music with more than one of their five senses owe special gratitude to that heritage.