Savant Syndrome: What It Is, How It Links to Autism and What IQ Misses

What is savant syndrome?

The psychiatrist Darold Treffert described it as an "island of genius" against a background of disability (Treffert, 2009). Savant comes from the French savoir, "to know".

The British doctor John Langdon Down named it "idiot savant" in 1887, when "idiot" was a technical term for an IQ below 25. Because the label became offensive, Treffert proposed "savant syndrome" instead in 1988 (Treffert, 2014).

It is not a medical diagnosis and is not listed in the DSM-5. It describes a pattern of strengths on top of another condition, most often autism.

Types of savant syndrome

Treffert sorted savants in two ways: by how exceptional the skill is, and by how it appeared. He admitted the first scale is "subjective", but it is still the standard one.

By level of skill: splinter, talented and prodigious

By how it appears: congenital, acquired and sudden

The registry figures come from Treffert & Rebedew (2015) and Treffert & Ries (2021). The "sudden savant" category is the newest and least certain: it rests on 11 people who filled in an online survey. Since they have no disability, the authors said "sudden genius" may be a better name.

What skills do savants have?

In the 2015 registry report, music was the most common main skill, with art and memory close behind at about one in five each. Calendar calculation, naming the weekday of any date, is famous but was the main skill in only 5% of congenital savants, though many have it as a second skill.

Whatever the skill, Treffert found it is "always linked to massive memory" (Treffert, 2009). And blind musical savants with an intellectual disability, such as Leslie Lemke and Derek Paravicini, are strikingly over-represented. Nobody knows why.

Savant memory is narrow and deep, not a general camera-like recall. Formal testing finds eidetic ("photographic") imagery in some savants but by no means all.

Savant syndrome and autism: how common is it?

Not all autistic people are savants, and not all savants are autistic. Treffert estimated that up to one in ten autistic people have some savant ability, and that about half of all savants are autistic. The other half have another developmental condition, a brain injury or a brain disease (Treffert, 2009).

The "one in ten" figure comes from a 1978 survey in which parents of 5,400 autistic children reported special abilities in 531 (Rimland, 1978). Studies using stricter or looser definitions produced very different numbers.

Savant skills are much rarer outside autism. A 1977 survey of institutions found about one savant per 2,000 residents with an intellectual disability, and a 2000 Finnish survey found about 1.4 per 1,000 (Treffert, 2009). We could not trace the "one in a million" figure seen on many websites to any study.

Savants are more often male: about six to one in Treffert's 2009 review and four to one in his later registry. In that registry 75% of congenital savants were autistic, but it collects cases sent in by families and clinicians, so it is not a population sample (Treffert & Rebedew, 2015).

Savant syndrome and IQ

Most savants score below average on IQ tests, but low IQ is not part of the definition. Treffert wrote that most savants tested have IQs between 50 and 70, but "in some instances IQ can be as high as 125, or even higher" (Treffert, 2014). Almost all cases occur in people with an IQ above 40 (Treffert, 2009).

Howlin and colleagues tested 137 autistic people (average age 24) and found that no one with a non-verbal IQ below 50 had a savant skill (Howlin et al., 2009). Some underlying reasoning ability seems to be needed.

Two documented scores show how little the number says. Leslie Lemke, a blind musical savant, scored 58 on the WAIS-R using verbal tests only, because the performance tests rely on sight (Treffert, 2014). Kim Peek scored 87 overall in 1988, and his assessors wrote that the score was "not a valid description of his intellectual ability" (Treffert & Christensen, 2005). For other famous savants, such as Stephen Wiltshire, Daniel Tammet or Derek Paravicini, we found no published IQ score, so we do not give one.

Why IQ tests miss what savants can do

Treffert gave three reasons. IQ tests lean heavily on language, which many savants find hard. IQ captures only one kind of ability, so an extraordinary skill in another area barely registers. And communication or behaviour can make people hard to test accurately (Treffert, 2014).

Despite Lemke's score of 58, a 1989 study comparing his piano improvisations with a professional musician's found the difference lay in musical preference and personality rather than musicianship (Hermelin et al., 1989). Howard Gardner used savants as evidence for multiple intelligences, though support for that theory remains limited.

Savant, prodigy, gifted: what is the difference?

Famous people with savant syndrome

These are some of the best-documented savants. Every fact below comes from a published source.

Kim Peek, the real Rain Man

Kim Peek inspired the 1988 film Rain Man. He read a page in eight to ten seconds and had learned about 9,000 books by heart by 2005; the often-quoted 12,000 is a later, less certain figure. His recorded diagnosis was a developmental disorder "with no diagnosis of autistic disorder", and the film's story is fictional (Treffert & Christensen, 2005).

What the other cases show

Stephen Wiltshire, appointed MBE in 2006 for services to art, has kept and developed his skill into adulthood, and Leslie Lemke moved from copying music to improvising (Treffert, 2014), against the old idea that savants only copy. Cambridge researchers reported that Daniel Tammet, who recited pi from memory at Oxford in 2004 (Tammet, 2006), has synaesthesia (he experiences numbers as colours and shapes) and Asperger syndrome (Bor et al., 2007). Jason Padgett's account of his 2002 injury is his own; a 2013 brain-imaging study found that formulas which trigger his geometric images activated areas only in the left hemisphere (Brogaard et al., 2013).

What causes savant syndrome?

No single theory explains all savants, as Treffert himself said (Treffert, 2009). The table grades the main ideas by the strength of their evidence.

The left-hemisphere and acquired-savant evidence

From 1996, neurologist Bruce Miller and colleagues described people with frontotemporal dementia who developed new artistic skill; brain scans pointed to dysfunction at the front of the left temporal lobe (Miller et al., 1996; Treffert, 2014). Treffert linked this to Narinder Kapur's idea of "paradoxical functional facilitation": damage in one area releases abilities in another that it normally holds back (Kapur, 1996). This concerns specific damage, not "left-brained" or "right-brained" people, which is a myth.

Can brain stimulation create savant skills?

Not reliably. Allan Snyder's team in Sydney used magnetic stimulation (rTMS) to briefly dampen the left fronto-temporal area in 11 students; four changed their drawing style and some proofread better (Snyder et al., 2003). Snyder argues savants have "privileged access" to raw information other brains filter out (Snyder, 2009). The studies are small, the effects modest and temporary, and replication is limited.

Autism research adds another piece. Many autistic people process detail and perceive patterns unusually well, which may give some a head start on savant skills (Happé & Vital, 2009; Mottron et al., 2006; Baron-Cohen et al., 2009). That helps explain why savant skills are more common in autism, but not the half of savants who are not autistic.

Savant syndrome myths and facts

Is there a test for savant syndrome?

No. There is no validated savant syndrome test, online or clinical. It is recognised by describing a person's skills alongside an underlying condition that a doctor or psychologist assesses. Online "hidden savant" quizzes are entertainment, not assessment.

If you are concerned about a child's development, or about a sudden change in an adult's abilities after an injury or illness, see a qualified professional. A new skill in later life can, rarely, accompany a brain condition such as dementia.

An IQ test measures something different: general reasoning across several areas. It will not detect a savant skill, but it can show your overall pattern of strengths.

Sources

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• Treffert, D. A. (2014). Savant syndrome: realities, myths and misconceptions. Journal of Autism and Developmental Disorders, 44(3), 564–571. https://doi.org/10.1007/s10803-013-1906-8
• Treffert, D. A., & Rebedew, D. L. (2015). The savant syndrome registry: a preliminary report. WMJ, 114(4), 158–162. https://wmjonline.org/wp-content/uploads/2015/114/4/158.pdf
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