Savant syndrome, sometimes abbreviated as savantism, is not a recognized medical diagnosis, but researcher Darold Treffert describes it as a rare condition in which people with developmental disorders have one or more areas of expertise, ability, or brilliance that are in contrast with the individual's overall limitations. Treffert says the condition can be genetic, but can also be acquired.^[1]

According to Treffert, about half of all people with savant syndrome have autistic disorder, while the other half have another developmental disability, mental retardation, brain injury or disease. He says, "... not all autistic people have savant syndrome and not all people with savant syndrome have autistic disorder".^[1] Other researchers state that autistic traits and savant skills may be linked,^[2] or have challenged some earlier conclusions about savant syndrome as "hearsay, uncorroborated by independent scrutiny".^[3]

Though it is even more rare than the savant condition itself, some savants have no apparent abnormalities other than their unique abilities. This does not mean that these abilities weren't triggered by a brain dysfunction of some sort but does temper the theory that all savants are disabled and that some sort of trade-off is required.^[4] (see Prodigious Savants below)

According to Treffert, something that almost all savants have in common is a prodigious memory of a special type, a memory that he describes as "very deep, but exceedingly narrow". It is narrow in the sense that they can recall but have a hard time putting it to use (for more on this see section on savants in Advanced Memory).^[1]

Savant-like skills may be latent in everyone and have been simulated in neurotypical people by directing low-frequency magnetic pulses into the brain's left front temporal lobe, which is thought to activate the region and allow for more-direct processing of a savant-like task involving rapid counting.^[5]

Savant syndrome is poorly understood. No widely accepted cognitive theory explains the combination of talent and deficit found in savants.^[6] It has been suggested that autistic individuals are biased towards detail-focused processing and that this cognitive style predisposes both autistic and nonautistic individuals to savant talents.^[7] Another hypothesis is that hyper-systemizing predisposes people to show talent, where hyper-systemizing is an extreme state in the empathizing–systemizing theory that classifies people based on their skills in empathizing with others versus systemizing facts about the external world,^[8] and that the attention to detail shown by many savants is a consequence of enhanced perception or sensory hypersensitivity in autistic individuals.^[8][9] It has also been suggested that savants operate by directly accessing low-level, less-processed information that exists in all human brains but is normally not available to conscious awareness.^[5]

It has been suggested that people with autism develop savant skills as a response to their impaired social abilities. I.e. due to not being able to understand social interactions innately they have to pay close attention to how people act and build up a reservoir of learnt interactions that they can understand and make use of. The way they function therefore predisposes them to a tendency towards analysis and storing information, hence the 'enhanced' memory. What one will often find in people with this condition is that they have difficulty remembering things such as people's names or recognizing people's faces as easily as people without ASD as they may not perceive this to be as important as perhaps the elements in the periodic table or the triangle numbers etc. This however varies between individuals and an ASD savant who at a young age were to identify attributing peoples faces to their name as a very important skill to posses would have exceptional skills in this area exceeding that of the ‘normal’ population.

Savant syndrome is six times more frequent in males than females, and this difference is not entirely explained by the preponderance of males in the autistic population. This has led to suggestions that the Geschwind–Galaburda hypothesis applies to savant syndrome where both the brain injury and savantism appear to be congenital.^[1]

According to Treffert:^[1]

• One in ten autistic people has savant skills.
• 50% of savants are autistic; the other 50% often have different disabilities, mental retardation, brain injuries, or brain diseases.
• Male savants outnumber female savants 6:1.

A 2009 British study of 137 autistic individuals found that 28% met criteria for a savant skill, that is, a skill or power "at a level that would be unusual even for normal people"; the study suggested that the number is likely to be an underestimate, with the true value being at least a third of individuals with autism.^[10]

There have so far been no studies on people of varying sexes or genders other than the standard male or female binary.

According to Treffert, the term idiot savant (French for "learned idiot" or "knowledgeable idiot") was first used to describe the condition in 1887 by John Langdon Down, who is known for his description of Down Syndrome. During the late-19th and early-20th century, "Idiot" was a scientifically acceptable term to refer to a person whose IQ was less than 20. The term idiot savant was later described as a misnomer because almost all reported cases since that time occur in people with IQ more than 40. The term autistic savant was also used during this time period as a diagnosis for this disorder. Like idiot savant, the term autistic savant also became looked at as a misnomer because only one-half of those who were diagnosed at the time with savant syndrome were autistic. Upon realisation of the need for accuracy within the diagnosis and dignity towards the individual, the term savant syndrome became widely accepted terminology.^[1]

Kim Peek was the basis for the 1988 fictional film Rain Man because he was a megasavant.^[11]

A prodigious savant is someone whose skill level would qualify him or her as a prodigy, or exceptional talent, even in the absence of a cognitive disability. Prodigious savants are those individuals whose abilities would be considered phenomenal or genius even in a person without any limitations or special diagnosis of impairment. The most common trait of these prodigious savants is their seemingly limitless mnemonic skills, with many having eidetic or photographic memories. Indeed, prodigious savants are extremely rare, with fewer than one hundred noted in more than a century of literature on the subject. Treffert, the leading researcher in the study of savant syndrome, estimates that fewer than fifty or so such individuals are believed to be alive in the world today. The website of the Wisconsin Medical Society lists 29 savant profiles.^[12] Darold Treffert is past-president of the society.

The following are well-known people with savant syndrome, noted for their talent in their identified fields:

• Kim Peek, mnemonist, speed reader and calculator, although not autistic ^[13]
• Daniel Tammet, British high-functioning autistic savant (mathematical synesthaesia, language absorption, and memory)^[4][14]
• Alonzo Clemons, American clay sculptor^[15]
• Tony DeBlois, blind American musician^[16]
• Leslie Lemke, blind American musician^[17]
• Jonathan Lerman, American artist^[18]
• Thristan Mendoza, Filipino marimba prodigy^[19]
• Derek Paravicini, blind British musician^[20]
• Gilles Tréhin, artist, author
• James Henry Pullen, gifted British carpenter^[21]
• Matt Savage, Canadian autistic jazz prodigy^[22][23]
• Henriett Seth-F., Hungarian autistic savant, poet, writer and artist^[24]
• Stephen Wiltshire, British architectural artist^[25]
• Richard Wawro, British artist^[17]
• George and Charles Finn, calendar calculator twins^[26][27]
• Florence 'Flo' and Katherine 'Kay' Lyman, calendar calculator twins. Featured in a documentary produced by TV network TLC entitled Twin Savants: Flo & Kay ^[28]
• Temple Grandin, a Doctor of Animal Science at Colorado State University, and consultant to the livestock industry in animal behavior^[29]
• Howard Potter, British autistic savant (mathematics, memory)
• Brent Navon, American autistic savant (memory, genetics)