PSYCHOLOGY Synesthesia, the condition in which the stimulation of one sense leads to consciously experiencing another sense, is of interest to researchers who are working to learn more about the interaction of sensory receptors and the brain. ''Simon Baron-Cohen, PhD, who studies synesthesia at the University of Cambridge,... proposes that synesthesia results from a genetically driven overabundance of neural connections in the brain. Ordinarily, Baron-Cohen explains, different sensory functions are assigned to separate modules in the brain, with limited communication between chem. In synesthesia, Baron-Cohen and his colleagues posit, the brain's architecture is different. Synesthetes' brains, they believe, ore equipped with more connections between neurons, causing the usual modularity to break down and giving rise to synesthesia. Noropa University psychologist Peter Grossenbacher, PhD, believes that there's likely a genetic root to synesthesia, but Grossenbacher and his colleagues suspect a different brain mechanism. We don't need to posit some abnormal architecture of connections in order to account for synesthesia," Grossenbacher argues. Instead, he proposes that in the brains of synesthetes, "feed-backward" connections that carry information from high-level multisensory areas of the brain back to single-sense areas ore not properly inhibited (prevented.) Ordinarily, information processed in such multisensory areas is allowed to return only to its appropriate single-sense area. But in synesthetes' brains, Grossenbacher argues, that inhibition is disrupted somehow." -Siri Carpenter, "Everyday Fantasia: The World of Synesthesia," Monitor on Psychology, March 2001. What do psychologists hope to learn by studying synesthesia?