Synesthetes and their rare ability of sense stimulation could shine light on ways to aid people with learning disabilities.
by Sharleen Dua, Jennifer Park, Kelvin Noronha, Maxwell Ruckstuhl l Staff Writers l UTS Vol. 3 (2012-2013)
Remember the refrigerator magnet alphabet set you had as a kid? You would use the letters to spell out words in vibrant colors. Imagine if every letter and number had a unique color associated with it: one that you saw even if the shape wasn’t colored. Each word would be a vivid picture and opening a book would reveal a rainbow on every page.
This ability is known as grapheme-color synesthesia, and it’s a fact of everyday life for synesthetes of this variety. People who exhibit this condition associate particular colors with symbols — “C” and “S” might be yellow, while “D” and “H” could be red.
There are many forms of synesthesia, all of which stem from connections between the different lobes in the brain. Variants are classified by the associated stimuli and sensory feedback they elicit. Those with lexical–gustatory synesthesia, for example, associate the sounds of speech with certain tastes. Sound–color synesthesia results in vibrant mental images when subjects hear music notes or even everyday background noise.
According to a 2009 study published in the journal TECCOGS, most synesthetes are not aware of their atypical perceptive ability, but when recognized, synesthesia can be beneficial. Many people with the sound–color variety, such as famed composer Franz Liszt, have perfect pitch — when a tone is played, they are able to accurately identify it. Grapheme-color synesthetes have also been known to be gifted mathematicians. However, these seemingly supernatural abilities are rare.
Priya Patel, a Marshall College sophomore, became involved in synesthesia research after learning about a neurological condition called “phantom limb pain” prevalent in Haitian amputee earthquake victims. Victims suffering from this condition continue to feel painful sensations in their amputated limbs.
Patel’s passion for biology and medicine began at a young age when her mother suffered a brain hemorrhage. Patel was fascinated by how quickly and effectively the doctors were able to treat the problem. This interest soon developed into a desire to conduct research in neurology and medicine, leading her to choose to attend UCSD because the faculty includes acclaimed psychology professor, V.S. Ramachandran. Ramachandran has pioneered work in both synesthesia and in phantom limb therapy, which employs a box with a mirror to “trick” the brain into believing that the image of a limb is real and then uses the association between vision and touch to treat the pain.
When she first learned about synesthesia, Patel’s curiosity was piqued by the many different research options available to her in the field. She and her fellow researchers chose to test subjects with grapheme–color synesthesia because it is the most common variant (it occurs in about 1% of humans) and is thus the most practical form of synesthesia to study.
Patel aimed to determine whether or not subjects exhibiting grapheme–color synesthesia recognize colors subconsciously before processing the letters themselves. This process is called “blindsight,” sonamed for the subjects’ ability to process visual feedback without consciously seeing. To evaluate her hypothesis, Patel presented subjects with puzzle pictures containing hidden or mirrorreversed letters. Because the letters were not in typical arrangements, they were intended to be difficult for normal subjects to immediately recognize.
Patel, along with fellow researcher Elizabeth Seckel and faculty advisor Ramachandran, hypothesized that synesthetes would be able to recognize the reversed letters more quickly than normal subjects, who are limited to cues from the shape of the letters.
The study included 15 subjects, four of whom exhibited grapheme–color synesthesia, and recognition time was measured using a simple stopwatch. Patel found that the difference in recognition time between grapheme–color synesthetes and controls was extraordinary — the synesthetes were consistently three times quicker. These results suggest that synesthetes do in fact process letters with a form of blindsight, speeding up the cognition process. Visual recognition typically occurs in the fusiform gyrus, a visually-oriented part of the brain’s temporal lobe.
However, Patel’s research may suggest that the observed subconscious recognition may depend on the neighboring V4 section of the visual cortex. The findings potentially indicate that lowerlevel sensory processing of the colors occurs first and and is followed by the higherlevel recognition of the graphemes in the fusiform gyrus through synaptic connections.
Some researchers believe that artificially inducing synesthesia might eventually play a role as a learning aid for patients with autism. A small number of autistic people have trouble identifying objects and symbols, and efforts are being made to devise a viable method of “environmental” stimulation, in which patients are repeatedly exposed to colored letters and numbers to help improve the speed and accuracy of their recognition. Researchers generally believe, however, that grapheme–color synesthesia is not produced by environmental factors, but rather that it stems from “hardwired” connections in the brain. If they are right, then an effective treatment for this aspect of autism would have to reshape the brain, perhaps by increasing the number of synaptic connections in the visual cortex.
Although we currently have no way to accomplish such changes, the possibilities suggested by Patel’s results hold vast implications for the future of mental treatments. Patel remarked that such a treatment, if found, could “change the lives of millions of Americans who have learning disabilities.” The topic has certainly made its mark on Patel — she plans to continue her work in the field and pursue a career in neurosurgery or neuroscience research.
WRITTEN BY SHARLEEN DUA, JENNIFER PARK, KELVIN NORONHA, AND MAXWELL RUCKSTUHL.
Sharleen Dua is a Human Biology major from Sixth College. She will be graduating in 2016. Jennifer Park is a General Biology major from Thurgood Marshall College. She will be graduating in 2016. Kelvin Noronha is a Physiology & Neuroscience major from Eleanor Roosevelt College. He will be graduating in 2016. Maxwell Ruckstuhl is a Physiology & Neuroscience major from John Muir College. He will be graduating in 2016.