Islands of Genius: How Savants Do What They Do
What happens in the brain to cause the incredible abilities of the savant?
Posted Aug 31, 2014
“Savant syndrome” is the name for a rare but extraordinary condition in which someone with serious mental impairment (often some form of autism) displays a spectacular “island of genius” amidst his overall disability.
Take, for example, a child who is mute and non-communicative but has the bizarre ability to do any jigsaw puzzle placed in front of him picture side down, with machine-like rapidity. Just by looking at the shapes of, say, 200 pieces, he can quickly put the puzzle together. Or consider another savant, blind from birth, who, at 14 years old, played Tchaikovsky’s Piano Concerto #1 from beginning to end flawlessly, having heard it just once. Or the late Kim Peek (who inspired Dustin Hoffman’s portrayal in the film Rain Man), who would read books extremely rapidly – one page with the right eye and the other with the left. He also memorized literally thousands of books, each from reading just once.
What all savants have in common is prodigious, almost uncanny memory. This type of memory, while deep, is also narrow, linked solely to their particular ability. These abilities cluster into 5 major categories: music, art, lighting calculation, calendar calculation, and visual-spacial ability (such as the jigsaw puzzle kid, or a man who can hit golf balls with enormous accuracy, so much so that they all land within a few feet of one another). Brain damage, generally in the left hemisphere, is endemic to nearly all congenital savants. (Some people acquire savant-like skills later in life; these nearly always appear in the aftermath of a head injury. More about these “acquired” savants later.) About half of the individuals with savant syndrome have an Autism Spectrum Disorder (ASD), while the other 50% have some other form of central nervous system damage or disease. Kim Peek, for instance, lacked a corpus callosum, the bundle of fibers that connect the brain hemispheres. He also had substantial other central nervous system damage. Not everyone with ASD, of course, will have savant abilities. About one out of 10 people with ASD do.
The best explanation of what happens in the brain of a savant (whether congenital or acquired) is this. Damage occurs to the left side of the brain, with higher-level memory circuits also sustaining damage. Parts of the brain that are undamaged are recruited to compensate, as are lower-level memory capacities. Rewiring occurs, and dormant capacity from the newly wired area is released. Dr. Darold Treffert of the University of Wisconsin – the world’s foremost authority on savants – terms this process “the 3 Rs”: recruitment, rewiring, release. The capacities that savants draw upon come from fast, pre-conscious mental activity; this isn’t the executive level ‘reasoning’ that most of us engage in. In general, creativity and cognitive flexibility are severely limited. In their place: automatic, rigid, rule-based processing.
Why are almost all savants male? One theory suggests that any number of disorders involving the disruption of the brain’s left hemisphere (such as savantism, autism, dyslexia, delayed speech, stuttering, and hyperactivity) will inevitably occur much more often in boys. This is because the left hemisphere typically completes its development later than the right hemisphere – and is, therefore, susceptible to prenatal influences for a longer period. In the developing male fetus, for example, circulating testosterone can slow the growth of the left hemisphere. This can trigger “recruitment,” with the right hemisphere becoming bigger and more dominant. (The cerebral lateralization theory, proposed by Norman Geschwind and Albert Galaburda in 1987, is discussed here.)
Perhaps the most incredible manifestation of savant syndrome is that of the “acquired” savant. Here, prodigious skill – especially in art or music – emerges completely unexpected in people who have suffered a head injury, stroke, dementia, or other form of brain damage. Take the 56-year-old builder who, after surviving a stroke, “began filling several notebooks with poems and verse; he had never written poetry prior to that time. Following that, [he] began to paint expansively and expressively, spending almost all of his time painting and sculpting.” Or consider the 42-year-old orthopedic surgeon who, in the aftermath of being struck by lightning, developed an insatiable desire to listen to classical piano music – a complete departure from his longtime taste for rock. He sought out Chopin recordings, and had such a strong desire to play them that he taught himself. Close on the heels of this impulse, he started hearing music in his own head – “an absolute torrent” that would intrude into whatever he was doing. It became “enjoyable, addicting, and overwhelming.” Over several years, he wrote down transcriptions of what he was hearing, ultimately recording and performing his own “Lightning Sonata.”
The evidence suggests that acquired savant syndrome occurs the same way as the congenital kind – from damage to the left side of the brain. The 3 Rs spring into action: recruitment, rewiring, and release. Exceptional abilities that were previously dormant rise to the surface. More accurately, they take over someone’s personality, impelling him or her to express these new capacities. Treffert believes that acquired savant syndrome indicates latent ability within everyone – that all of us have some “Rain Man” capacity within.
The implications are even greater than that. To get at them, we need to take a closer look at how savants and prodigies (who have savant-like abilities but without physical or mental impairments) “know things they have never learned.”