When J. Langdon Down first described savant syndrome in 1887, coining its name and noting its association with astounding powers of memory, he cited a patient who could recite Edward Gibbon's The Decline and Fall of the Roman Empire verbatim. Since then, in almost all cases, savant memory has been linked to a specific domain, such as music, art or mathematics. But phenomenal memory is itself the skill in a 54-year-old man named Kim Peek. His friends call him "Kim-puter."
   He can, indeed, pull a fact from his mental library as fast as a search engine can mine the Internet. He read Tom Clancy's. The Hunt for Red October in one hour and 25 minutes. Four months later, when asked, he gave the name of the Russian radio operator in the book, referring to the page describing the character and quoting several passages verbatim. Kim began memorizing books at the age of 18 months, as they were read to him. He has learned 9,000 books by heart so far. He reads a page in eight to 10 seconds and places the memorized book upside down on the shelf to signify that it is now on his mental "hard drive."

Overview/Peek's Peaks Great powers of memory run through every known manifestation of savant skill. In the case of Kim Peek, memory is itself the skill. Kim's brain exhibits many abnormalities, including an absent corpus callosum. The role of that particular abnormality in Kim's case remains to be explained, but it evokes a question raised by the skills of all savants: Does brain damage stimulate compensatory development in some other area of the brain, or does it simply allow otherwise latent abilities to emerge? Kim's rote learning later developed into a form of associative thinking, with clear evidence of creativity. His success then helped him engage the wider world. The authors conclude that savant skills should never be dismissed but should be cultivated for the patient's intellectual and social development.

   Kim's memory extends to at least 15 interests-among them, world and American history, sports, movies, geography, space programs, actors and actresses, the Bible, church history, literature, Shakespeare and classical music. He knows all the area codes and zip codes in the U.S., together with the television stations serving those locales. He learns the maps in the front of phone books and can provide Yahoo-like travel directions within any major U.S. city or between any pair of them. He can identify hundreds of classical compositions, tell when and where each was composed and first performed, give the name of the composer and many biographical details, and even discuss the formal and tonal components of the music. Most intriguing of all, he appears to be developing anew skill in middle life. Whereas before he could merely talk about music, for the past two years he has been learning to play it.
   It is an amazing feat in light of his severe developmental problems-characteristics shared, in varying extents, by all savants. He walks with a sidelong gait, cannot button his clothes, cannot manage the chores of daily life and has great difficulties with abstraction. Against these disabilities, his talents-which would be extraordinary in any person-shine all the brighter. An explanation of how Kim does what he does would provide better insight into why certain skills, including the ordinarily obscure skill of calendar calculating {always associated with massive memory), occur with such regularity among savants. Recently, when an interviewer offered that he had been born on March 31, 1956, Kim noted,. in less than a second, that it was a Saturday on Easter weekend.
   Imaging studies on Kim's brain thus far show considerable' structural abnormality [see box on page 112]. These findings cannot yet be linked directly to any of his skills; that quest is just beginning. Newer imaging techniques that plot the brain's functions-rather than just its structure-should provide more insight, though. In the meantime, we believe it is worthwhile to document the remarkable things that Kim can do. People like him are not easily found, and it is useful to record their characteristics for future research. Savantism offers a unique window into the mind. If we cannot explain it, we cannot claim full understanding of how the brain functions.

An Unusual Brain
KIM WAS BORN on November 11,1951 (a Sunday, he will tell you). He had an enlarged head, on the back of which was an encephalocele, or baseball-size "blister," which spontaneously resolved. But there were also other brain abnormalities, including a malformed cerebellum. One of us (Christensen) did the initial MRI brain scans on Kim in 1988 and has followed his progress ever since.
   The cerebellar findings may account for Kim's problems with coordination and mobility. But more striking still is the absence of a corpus callosum, the sizable stalk of nerve tissue that normally connects the left and right halves of the brain. We do not know what to make of this defect, because although it is rare, it is not always accompanied by functional disorders. Some people have been found to lack the structure without suffering any detectable problems at all. Yet in people whose corpus callosum has been severed in adulthood, generally in an effort to prevent epileptic seizures from spreading from one hemisphere to the other, a characteristic "split-brain" syndrome arises in which the estranged hemispheres begin to work almost independently of each other.
   It would seem that those born without a corpus callosum somehow develop back channels of communication between the hemispheres. Perhaps the resulting structures allow the two hemispheres to function, in certain respects, as one giant hemisphere, putting functions normally rather separate under the same roof, as it were. If so, then Kim may owe some of his talents to this particular abnormality. In any case, the fact that some people lacking a corpus callosum suffer no disabilities, whereas others have savant abilities, makes its purpose less clear than formerly thought. Neurologists joke that its only two certain functions are to propagate seizures and hold the brain together.
   Theory guides us in one respect. Kim's brain shows abnormalities in the left hemisphere, a pattern found in many savants. What is more, left hemisphere damage has been invoked as an explanation of why males ~re much more likely than females to display not only savantism but also dyslexia, stuttering, delayed speech, and autism. The proposed mechanism has two parts: male fetuses have a higher level of circulating testosterone, which can be toxic to developing brain tissue; and the left hemisphere develops more slowly than the right and therefore remains vulnerable for a longer period. Also supporting the role of left hemisphere damage are the many reported cases of "acquired savant syndrome," in which older children and adults suddenly develop savant skills after damage to the left hemisphere.
   What does all this evidence imply? One possibility is that when the left hemisphere cannot function properly, the right hemisphere compensates by developing new skills, perhaps by recruiting brain tissue normally earmarked for other purposes. Another possibility is that injury to the left hemisphere merely unveils skills that had been latent in the right hemisphere all along, a phenomenon some have called a release from the "tyranny" of the dominant left hemisphere.
   Kim underwent psychological testing in 1988. His overall IQ score was 87, but the verbal and performance, subtests varied greatly, with some scores falling in the superior range of intelligence and others in the mentally retarded range. The psychological report concluded, therefore, that "Kim's IQ classification is not a valid description of his intellectual ability."The "general intelligence" versus "multiple intelligences" debate rages on in psychology.. We believe that Kim's case argues for the latter point of view.
   Kim's overall diagnosis was "developmental disorder not otherwise specified," with no diagnosis of autistic disorder. Indeed, although autism is more commonly linked with savantism than is any other single disorder, only about half of all savants are autistic. In contrast with autistic people, Kim is outgoing and quite personable. One thing that does seem necessary for the full development of savant skills is a strong interest in the subject matter in question.

Memory and Music
IN KIM'S CASE, all the interests began in rote memorization but later progressed to something more. Although Kim generally has a limited capacity for abstract or conceptual thinking-he cannot, for example, explain many commonplace proverbs-he does comprehend much of the material he has committed to memory. This degree of comprehension is unusual among savants. Downs himself coined the interesting phrase "verbal adhesion" to describe the savant's ability to remember huge quantities of words' without comprehension. Sarah Parker, a graduate student in psychology at the University of Pennsylvania, in a description of a savant named Gordon stated it more colorfully when she noted that "owning a kiln of bricks does not make one a mason." Kim not only owns a large kiln of bricks, he has also become a strikingly creative and versatile word mason within his chosen areas of expertise.
   Sometimes his answers to questions or directions are quite concrete and literal. Once when asked by his father in a restaurant to "lower his voice," Kim merely slid lower into his chair, thus lowering his voice box. In other cases, his answers can seem quite ingenious. In one of his talks he answered a question about Abraham Lincoln's Gettysburg Address by responding, "Will's house, 227 North West Front Street. But he stayed there only one night-he gave the speech the next day." Kim intended no joke, but when his questioner laughed, he saw the point; since then, he has purposely recycled the story with humorous intent and effect.
   Yet Kim does have all undeniable power to make clever connections. He once attended a Shakespeare festival sponsored by a philanthropist known by the initials O.C., whose laryngitis threatened to keep him from acknowledging a testimonial. Kim-a fan of Shakespeare, and like him, an incorrigible punster-quipped, "O.C., can you say?"
   Such creative use of material that had originally been memorized by rote can be seen as the verbal equivalent of a musician's improvisation. Like the musician, Kim thinks quickly, so quickly that it can be difficult to keep up with his intricate associations. Often he seems two or three steps ahead of his audiences in his responses.
   A rather startling new dimension to Kim's savant skills has recently surfaced. In 2002 he met April Greenan, director of the McKay Music Library and professor of music at the University of Utah. With her help, he soon began to play the piano and to enhance his discussion of compositions by playing passages from them, demonstrating on the keyboard many of the pieces he recalled from his massive mental library. Kim also has remarkable long-term memory of pitch, remembering the original pitch level of each composition.