How common is savant syndrome?
Approximately one in 10 (10 percent) of individuals with autistic disorder have some savant skills. In other forms of development disability, mental retardation or brain injury, savant skills occur in less than 1 percent of such individuals (approximately 1:2000 in people with mental retardation). These other forms of mental disability are much more common than autistic disorder. However, it turns out that approximately 50 percent of individuals with savant syndrome have autistic disorder, and the other 50 percent have some other form of developmental disability, mental retardation, or brain injury or disease. As a result, not all savants are autistic, and not all autistic individuals are savants.
What is the range of savant skills?
Savant skills exist over a spectrum of abilities. The most common savant abilities are called splinter skills. These include behaviors, such as obsessive preoccupation with, and memorization of, music and sports trivia, license plate numbers, maps, historical facts or obscure items, such as vacuum cleaner motor sounds, for example. Talented savants are those individuals in whom musical, artistic, mathematical or other special skills are more prominent and highly honed, usually within an area of single expertise and are very conspicuous when viewed against their overall handicap. The term prodigious savant is reserved for those very rare individuals in this already uncommon condition where the special skill or ability is so outstanding that it would be spectacular even if it were to occur in a non-handicapped person. There are probably fewer than 50 prodigious savants living worldwide at the present time who would meet this high threshold of special skill.
What are the typical savant skills?
Particularly striking is the consistent observation also over this past century that savant skills typically, and curiously, are generally confined to only about five general areas of expertise - music, art, lightning calculating or other mathematical skills, calendar calculating and mechanical/spatial skills. This very limited, but spectacular, array of special skills is noteworthy considering the much wider palette of skills in the human repertoire, and the rarity of the obscure skill of calendar calculating in the general population, which seems an ability almost universal, innately so, among savants.
Music is the generally the most common savant skill - usually playing piano by ear and almost always with perfect pitch. Other percussion instruments, such as marimba or drums can be mastered as well, but much less frequently. Musical performance abilities predominate, but outstanding composing skills have been documented as well, most often linked to performance ability, but not necessarily so. The triad of mental disability, blindness and musical genius occurs with a curious, conspicuous frequency in reports over this past century, particularly when one considers the relative rarity of each of those circumstances individually.
Artistic talent, usually painting or drawing, is seen next most frequently. Other forms of artistic talent can occur as well, such as sculpting. Lightning calculating or other mathematical skills, such as the ability to compute multi-digit prime numbers contrasted with the inability to perform even simple arithmetic, has often been reported. Mechanical ability, constructing or repairing intricate machines or motors for example, or spatial skills such as intricate map and route memorizing, or being able to compute distances with precise accuracy just from visualization, do occur, but are seen somewhat less frequently.
Calendar calculating is curiously and conspicuously common among savants, particularly considering the rarity of that obscure skill in the general population. Beyond being able to name the day of the week that a date will occur on in any particular year, calendar calculating includes being able to name all the years in the next 100 in which Easter will fall on March 23rd, for example, or all the years in the next 20 when July 4 will fall on a Tuesday. The so-called ‘calculating twins’ reported extensively in the literature, have a calendar calculating span of over 40000 years backward or forward in time. They also remember the weather for every day of their adult life.
Other skills are occasionally seen including multilingual acquisition ability or other unusual language (polyglot) skills, exquisite sensory discrimination in smell or touch, perfect appreciation of passing time without access to a clock face, or outstanding knowledge in specific fields such as neurophysiology, statistics, history or navigation, to name a few. While always controversial, there have been some reports of extra-sensory perception skills occurring in savants as well.
Typically a particular one of these skills occurs singly in each person with savant syndrome. However in some instances multiple skills occur in the same person. Regardless of the type of skill, it is always combined with prodigious memory, and it is this special kind of memory-extraordinarily deep but very, very narrow - that cuts across all the various special skills and welds the condition of savant syndrome together.