Journal of Child Psychology and Psychiatry 45:5 (2004), pp 899–911
Annotation: The savant syndrome
Pamela Heaton1 and Gregory L. Wallace2
1
Psychology Department, Goldsmiths College, University of London, UK; 2Social, Genetic & Developmental
Psychiatry Research Centre, Institute of Psychiatry, London, UK
Background: Whilst interest has focused on the origin and nature of the savant syndrome for over a
century, it is only within the past two decades that empirical group studies have been carried
out. Methods: The following annotation briefly reviews relevant research and also attempts to address
outstanding issues in this research area. Traditionally, savants have been defined as intellectually
impaired individuals who nevertheless display exceptional skills within specific domains. However,
within the extant literature, cases of savants with developmental and other clinical disorders, but with
average intellectual functioning, are increasingly reported. Results: We thus propose that focus
should diverge away from IQ scores to encompass discrepancies between functional impairments and
unexpected skills. It has long been observed that savant skills are more prevalent in individuals with
autism than in those with other disorders. Therefore, in this annotation we seek to explore the
parameters of the savant syndrome by considering these skills within the context of neuropsychological
accounts of autism. A striking finding amongst those with savant skills, but without the diagnosis of
autism, is the presence of cognitive features and behavioural traits associated with the disorder. Conclusions: We thus conclude that autism (or autistic traits) and savant skills are inextricably
linked and we should therefore look to autism in our quest to solve the puzzle of the savant syndrome. Keywords: Savant, autism, talent, intelligence.
History
Fifteen years have passed since Neil O’Connor and
Beate Hermelin published their annotation ‘low
intelligence and special abilities’ in the Journal of
Child Psychology and Psychiatry. This paper described research findings by the authors as well as
other researchers in the savant field and raised
important questions about the co-occurrence of low
levels of intelligence and high-level skills in savants.
These studies marked a sea change in approach to
the study of the savant, bringing a scientific rigour to
an area of psychology that had historically been
dominated by anecdotal reports. Since the publication of this article (O’Connor & Hermelin, 1988), interest in this phenomenon has continued unabated
and has culminated in the publication of well over
100 journal articles and book chapters as well as six
books (Hermelin, 2001; Howe, 1989; Obler & Fein,
1988; Sacks, 1995; Smith & Tsimpli, 1995; Treffert,
1989) in the English language alone. A comprehensive review of this literature is beyond the scope of
our annotation so readers are referred to Miller’s
(1999) recent paper on this topic. Instead, we will
here focus primarily upon research and theoretical
issues arising since the publication of the seminal
paper of O’Connor and Hermelin (1988).
Defining the savant
The term ‘idiot-savant’ was first used by Down (1887)
to describe intellectually impaired individuals with
contrasting outstanding abilities. More recently,
there has been a terminological shift and the terms
‘monosavant’ (Charness, Clifton, & MacDonald,
1988) and ‘savant syndrome’ (Treffert, 1989) have
come into general usage. Whilst the pejorative connotations of the ‘idiot-savant’ label necessitated such
a change, these more current terms inevitably fail to
adequately reflect the paradoxical nature of this
intriguing syndrome.
Although rarely mentioned in the extant literature,
one topic worthy of discussion is the examination of
how the savant syndrome has traditionally been
defined. This conceptual controversy was recently
reviewed by Miller (1998), who proposed that defining savant status in an individual should be similar
to the approach taken for defining learning disability
in the United States. More specifically, Miller
endorses a ‘discrepancy-based model’ wherein one
compares intra-individual performance across
functional domains. One example would be the
comparison of academic achievement (e.g., reading)
and intellectual functioning (measured by standardised IQ tests). Unfortunately, a reliance on
standardised tests that do not allow for difficulties in
reading comprehension and semantic processing
(e.g., Minshew & Goldstein, 2001) has often limited
our understanding of intra-individual performance
across domains. For example, George, one of the
calendar-calculating twins initially described by
Horwitz, Kesterbaum, Person, and Jarvik (1965) and
later by Sacks (1985), was unable to multiply 7 · 4,
although he could calculate the total number of days
in 4 weeks. The calendar-calculating savant described by Ho, Tsang, and Ho (1991) showed poor
performance on the Arithmetic subtest of the WAIS
Association for Child Psychology and Psychiatry, 2004.
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Pamela Heaton and Gregory L. Wallace
(Wechsler Adult Intelligence Scales) but quite good
performance on the Stanford Diagnostic Mathematical Test. In the Wechsler Arithmetic subtest, items
are presented as story problems, whereas the Stanford Diagnostic Mathematical Test relies on the
manipulation of numbers.
Related to Miller’s discrepancy-based model is
Treffert’s (1989) splinter skill category, which would
seem to be a natural consequence of the uneven
cognitive profile seen in developmental disorders like
autism (Happé & Frith, 1996; Rumsey, 1992) and
Williams syndrome (Bellugi, Lichtenberger, Mills,
Galaburda, & Korenberg, 1999). Here, specific skills
might be developmentally on-line, thus fulfilling
norms for chronological age, but providing a contrast
with overall mental age of subjects. Treffert’s formulation also extends to include talented and prodigious levels of skill, which reflect comparisons
both within and across groups, in the former case to
other cognitively impaired individuals and in the
latter case to cognitively unimpaired talented people.
Young (1995) used Treffert’s criteria in her comprehensive study of 51 savants and determined that
savant status should be reserved for those individuals falling in the talented and prodigious categories
as outlined by Treffert. Thus, Young validates the
use of across-group comparisons as appropriate
measures of savant talent.
Like Miller (1998), we propose that intra-individual comparisons could be of great utility in
defining the savant syndrome. However, we also
propose the utilisation of other measures (instead of
general intellectual functioning), such as adaptive
functioning, to contrast with unexpected skills.
Support for de-emphasising IQ derives from the
finding that approximately 20% of individuals with
autism (in whom savant skills are over-represented)
score in the average range on measures of nonverbal intelligence (Volkmar & Lord, 1999), and from
the fact that the majority of savants in Young’s
sample showed intellectual impairment at only mild
to borderline levels. Although Young’s study was not
population-based and therefore may not extrapolate
to the whole savant population, it is nevertheless the
largest savant group study carried out to date. Also
of relevance are reports of individuals with autism
who are considered savants despite average, or
above average, intellectual functioning (Heavey,
Pring, & Hermelin, 1999; Young & Nettlebeck, 1995).
Deficits in adaptive behaviour, which may be viewed
as difficulties in ‘everyday’ intelligence, are commonly reported in high-functioning individuals with
autistic spectrum disorders (e.g., Klin, 2000), thus
validating the inclusion of such subjects within the
savant category.
Crucial to defining the savant are questions
regarding the extent and nature of demonstrated
skills. As previously mentioned, Treffert (1989) has
delineated a three-tier classification system for the
differing skill levels observed. Typically, savants de-
velop calendar calculation, memory, music, art or
arithmetic skills (Hill, 1974). However, there are also
reports of savants with prime number identification
skills (Anderson, O’Connor, & Hermelin, 1999;
Hermelin & O’Connor, 1990; Kelly, Macaruso, &
Sokol, 1997), mechanical (Brink, 1980; Hoffman &
Reeves, 1979; Tredgold, 1952), and linguistic skills
(Dowker, Hermelin, & Pring, 1996; Smith & Tsimpli,
1995). Also of relevance in situating the savant
syndrome are decisions about what constitutes a
savant skill. For example, hyperlexia (for review, see
Nation, 1999) generally involves a significant discrepancy between reading decoding and reading
comprehension, with the former being superior
(Snowling & Frith, 1986). However, hyperlexia is
rarely designated as a savant skill in the extant literature, partly due to developmental factors. More
specifically, this decoding skill eventually ceases to
be outstanding because there is a ceiling on ability.
But, in fact, at earlier points in development, hyperlexia meets criteria for a skill that is exceptional
relative to overall ability (Welsh, Pennington, &
Rogers, 1987), and exceptional relative to that of
normally developing peers, thus satisfying requirements of the traditional savant definition. Importantly, hyperlexia is most commonly noted in
autism, although it has also been observed in other
developmental disorders such as speech–language
impairment (Cohen, Hall, & Riccio, 1997), Williams
syndrome (Bellugi, Birhle, Neville, Jernigan, & Doherty, 1992), Turner’s syndrome (Temple & Carney,
1996) and idiopathic MLD (Snowling & Frith, 1986).
These findings highlight the importance of utilising a
uniform approach to defining savant status across
domains and disorders in order to assist researchers
in delineating their relevance to neurocognitive
models of various developmental disorders.
Rates of occurrence
Owing to a lack of rigorous epidemiological investigations, the true prevalence of savant skills in
autistic spectrum disorders and more broadly in
developmental disorders is unknown. However,
surveys carried out by Hill in 1977 and Rimland in
1978 provided important data regarding putative
numbers of savants in intellectually impaired and
autistic populations. In Hill’s study, 107 institutions
(out of 300 approached) for individuals with cognitive disabilities identified 54 savants, a prevalence
rate of approximately .06% or 1 in every 2000 cognitively impaired residents. However, Rimland
(1978) targeted parents of 5,400 children with autism, and here 531 individuals, constituting 9.8% of
the autistic population, were identified as savants.
This then suggests that there is a significantly
greater prevalence of savants in populations of autistic as opposed to intellectually impaired individuals. However, it should be noted that the
Annotation: The savant syndrome
respondents in Hill’s study were careworkers,
whereas Rimland’s respondents were parents, who
might have shown a positive bias in reporting their
children’s skills. It is also of relevance that in the
Hill (1977) study, criteria for savant status were
not clearly defined and the superintendents of the
various institutions screened relied on their own
operational definitions and interpretations.
Another difficulty in accurately determining the
co-occurrence of the savant syndrome and autism
concerns changes in diagnostic criteria and practice
in the past 25 years that have led to a sharp rise in
numbers of individuals diagnosed with autistic
spectrum disorders (Charman, 2002; Fombonne,
2002; Wing & Potter, 2002). This raises the possibility that many of the intellectually impaired savants described in the past research literature might
meet current criteria for an autistic spectrum disorder. Moreover, Young (1995) observed that all of
the 51 savants in her sample showed some characteristic autistic behaviours, although some had
never received a formal diagnosis. Case study descriptions of savants with complex patterns of disability (e.g., congenital blindness, intellectual
impairment and language disability) also frequently
make reference to behavioural features commonly
associated with autism (e.g., musical savants; Miller,
1989). Taken together, this evidence strongly suggests that savant talent is most closely associated
with autistic spectrum disorders. However, savant
talent is occasionally seen in individuals with other
psychological disorders and these will be further
discussed.
901
savant within the context of current models of
intelligence (for review, see Nettelbeck & Young,
1996) and to develop new models within which the
savant can be situated (Anderson, 1998), there has
been something of a change in direction and the
belief that the savant can inform our understanding
of the nature of intelligence has in itself become a
matter of speculation. Indeed, it has been suggested
that savants do not pose a challenge to current theorising about the nature of intelligence (Nettelbeck &
Young, 1996) as their behaviours are not essentially
intelligent (Spitz, 1995), but reflect purely localised
knowledge. However, data from empirical studies
(e.g., Anderson et al., 1999; Cowan, O’Connor, &
Samella, 2001; Heavey et al., 1999; Hermelin &
O’Connor, 1986; Miller, 1989; Mottron & Belleville,
1993, 1995; Pring & Hermelin, 1993; Pring, Hermelin, & Heavey, 1995; Young & Nettelbeck, 1994,
1995) clearly show that these skills are supported by
memory and information processing mechanisms
that contribute to, or underpin, general intelligence
(Nettelbeck & Young, 1999). Nevertheless, it remains
unclear as to whether savant skills have relevance to
notions and theories of intelligence, and from the
evidence so far accumulated, we are inclined to believe that savant skills are domain specific and
therefore somewhat independent from general intellectual functioning. One method for examining the
theoretical significance of savant skills is to utilise a
neuropsychological framework in which a variety of
basic cognitive processes are examined. Two of these
cognitive functions are highlighted here (i.e., memory and learning), as well as prominent neuropsychological theories that seek to explain the savant
syndrome.
Savant skills and intelligence
The earliest documented cases of savants provide
largely descriptive accounts of individuals then
described as ‘idiot-savants’. For example, Jebediah
Buxton (b. 1702, reported by Smith, 1983) showed
slow but impressive mental calculation abilities (see
Heavey, 2003), Thomas Wiggins (b. 1849, described
by Southall, 1979, 1983) was an accomplished
concert pianist (see Miller, 1989) and Gottfried Mind
(b. 1768) drew such realistic and detailed pictures of
cats that he became known as ‘The Cat’s Raphael’
(Hindermann, 1982). Because severe intellectual
disabilities were often documented in these individuals, the unexpected presence of outstanding
skills aroused significant interest. This juxtaposition
of skill and disability remained a question of key
theoretical interest for many years as it was believed
that the idiot-savant might help elucidate the nature
of intelligence. More specifically, it was thought that
they might provide insights into whether a general
intelligence factor (Spearman, 1927) should be discarded in favour of a model positing independent
intelligences (Gardner, 1983). However, whilst
researchers have attempted both to explain the
Memory and cognitive strategies
One suggestion that has frequently been made is
that savants show exceptional rote memory (Hill,
1978). However, if rote memory is defined as the
veridical encoding of information, this clearly does
not explain savant talents within the classical domains of music, art and calendar calculation, where
greater flexibility in the manipulation of domainspecific information is essential and indeed evident
in savants. For example, investigations into the
musical memory of savants (Sloboda, Hermelin, &
O’Connor, 1985; Young & Nettelbeck, 1995) show
that whilst long-term memory is good, or indeed exceptional, reproduction of heard materials is not
verbatim, and reproduction errors preserve the important structural characteristics of the compositions. Moreover, studies with calendar calculators
have shown how the regularities inherent within
calendars are extracted and utilised in on-line computation (Cowan et al., 2001; Heavey et al., 1999;
Nettelbeck & Young, 1996; O’Connor & Hermelin,
1984, 1987a, b, 1990). Findings from investigations
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Pamela Heaton and Gregory L. Wallace
comparing savants and normal individuals with talents in the same domain sometimes suggest that
similar mechanisms underpin skill in both groups.
For example, in one study of an autistic prime
number calculator, Anderson et al. (1999) found that
both the savant and a trained mathematician used
an algorithm described by Erastosthenes in the 3rd
century. Similarly, Kelly et al. (1997) found that a
calculating savant used similar computational
strategies to those of normal expert calculators. In
studies of art savants, participants have often been
shown to apply similar graphic representational
rules to those of unimpaired talented artists
(O’Connor & Hermelin, 1987a, b, 1990; Pring &
Hermelin, 1993; Pring et al., 1995; Selfe, 1983).
However, the savant draughtsman described by
Mottron and Belleville (1995) clearly used different
strategies to controls in graphic reproduction. This
savant began his reconstruction of the presented
models by drawing details and then progressing to
global outlines. This strategy has also been noted in
a high-functioning child with Asperger syndrome
and exceptional graphic talent (Wallace, personal
communication). Given the evidence outlined above,
it is clear that a categorical answer to the question of
whether savants use similar or different cognitive
strategies cannot be given. However, our position is
that many of the information processing mechanisms crucial to performance within savant domains
are spared in autism. For example, intact recognition
of patterns or artificial grammars has been noted in
autism (Klinger, Lee, Bush, Klinger, & Crump,
2001). Such abilities might well be crucial and provide building blocks for knowledge acquisition
within the domains of music and number. We also
believe that a detail-focused information processing
style, characteristic of autism (Happé, 1999), but
acquired by typically developing people during specialist training, advantages those with autism. Indeed, we propose that this cognitive style best
explains the overrepresentation of individuals with
this disorder in savant populations. Taking the
example of the most prevalent neurodevelopmental
disorder, Down syndrome, where savant skills are
not widely reported, we see an exaggeration of the
normal tendency to process stimuli globally. In a
study by Bellugi and colleagues (Bellugi, Birhle,
Jerningham, Trauner, & Doherty, 1990), participants with Down syndrome produced drawings that
were globally coherent but were weak on internal
detail. In contrast, a group of subjects with Williams
syndrome reproduced details but neglected global
outlines. Individuals with Williams syndrome typically show the lowest sub-test performance on the
Block Design task from the Weschler Intelligence
scales (Udwin & Yule, 1991; Bellugi, Wang, & Jernigan, 1994). This task requires subjects to perceptually segment visually presented designs in a way
that corresponds to a set of patterned blocks, which
are then used to replicate the design. Thus good
performance on the task requires both the disembedding and coherent reformulation of visual
segments. Repeatedly, studies examining performance on the Weschler Intelligence Scales by subjects with autism (Happé, 1994; Rumsey, 1992) have
found that the most frequent peak sub-test score
occurred on the Block Design task. This suggests
that in autism, unlike Down and Williams syndromes, both disembedding and reformulation abilities are intact. The savant artists previously
described apply a local processing strategy in picture
production but are nevertheless able to produce
output that is globally intact. Thus, whilst processing strategies are strongly featurally biased, this
does not appear to convey a disadvantage within
savant talent domains.
Whilst the question of similarities and dissimilarities in cognitive strategies between savants and
other gifted individuals may be controversial, it is
nevertheless clear that savant skills do not solely rely
on rote memory but instead reflect an enhanced or
spared ability to represent and manipulate highly
organised domain-specific information.
On standardised tests of memory savants do not
tend to show generally good levels of performance
(Howe, 1989). However, as previously suggested,
tests relying on intact comprehension and semantic
encoding skills may not be appropriate tools for
probing savant memory, especially where there is a
diagnosis of autism (Nettelbeck & Young, 1999).
Digit span is sometimes seen as a measure of shortterm memory (Jackson & Warrington, 1986), and
some investigators (Duckett, 1976; Spitz &
LaFontaine, 1973) have found that calendar calculators display better sub-test performance for digit
span than would be predicted from full-scale IQ.
However, this finding was not replicated in the
sample of calendar-calculating savants described by
Heavey (1997). Similarly, memory performance on
tests where stimuli reflect the savant domain has
been found to be good in some studies (Valentine &
Wilding, 1994; Heavey, 1997) but not in others
(Young, 1995). However, despite this lack of consensus, it remains the case that anecdotal reports of
savants invariably describe outstanding memory
abilities and it may be that methodological limitations rather than truly unexceptional memory accounts for this lack of experimental validation. For
example, in Young’s (1995) sample of individuals
with savant and splinter skills, 37 of 39 parents
reported precocious levels of memory. On a standardised measure, the Wechsler Memory ScalesRevised, Young found elevated performance on the
Delayed Memory Quotient, indicating good recall for
well-encoded information. Based on these findings,
Nettelbeck and Young (1996) suggest that declarative (rote) memory, facilitated by an ability to make
associations, is essential for savant skills. Converging evidence therefore suggests that memory is an
important cognitive component of savant skill.
Annotation: The savant syndrome
Indeed, exceptional memory may in itself constitute
a savant talent (e.g., Mottron, Belleville, Stip, &
Morasse, 1998).
Explicit and implicit learning
In savants with the diagnosis of autism, language
and communication impairments severely curtail
their ability to profit from explicit instruction. In
addition to these difficulties, intellectual impairment
is found in the majority of individuals with autism
spectrum disorders (Volkmar & Lord, 1999). Indeed,
studies of individuals without autism but with
intellectual impairment and/or Down syndrome
have shown deficits in explicit learning in comparison to controls (Carlesimo, Marotta, & Vicari, 1997),
so this difficulty appears to be a general outcome of
intellectual impairment. However, performance on
tasks of implicit learning reveals quite a different
pattern. Generally, individual differences within
normal populations on tasks of implicit learning are
smaller than those seen on explicit learning tasks
(Reber, Walkenfeld, & Hernstadt, 1991) and performance on some implicit learning tasks appears to be
relatively unaffected by intellectual impairment
(Ellis, Palmer, & Reeves, 1988). For example, in a
study testing implicit memory for spatial location
(Ellis, Woodley-Zanthos, & Dulaney, 1989) in college
students and cognitively impaired individuals, group
differences emerged only when IQ fell below 47. The
51 savants included in Young’s (1995) sample had
IQ scores ranging from 50 to 114. If, as this evidence
suggests, the majority of savants for whom IQ data is
available show impairment in the mild to borderline
categories, it may be that implicit learning mechanisms are unimpaired in savants. Of relevance to
this question are findings showing intact implicit
memory in subjects with autism and Asperger syndrome (Bowler, Matthews, & Gardiner, 1997; Kamio
& Toichi, 2000; Renner, Klinger, & Klinger, 2000;
Toichi & Kamio, 2001). Given these findings, the
development or adaptation of current implicit
learning paradigms in order to investigate domaingeneral and domain-specific implicit learning in
savants could provide a fruitful focus for future
research.
An important commonality amongst the various
savant skill areas is high internal structure (Miller,
1989) and we believe that this is potentially relevant
to our understanding of the savant syndrome. Each
of these domains has rules that govern the application of skills, and previous work (Heavey et al., 1999;
Miller, 1989; Nettelbeck & Young, 1996; O’Connor &
Hermelin, 1984, 1987a, b, 1990; Sloboda et al.,
1985) has alluded to the importance of organised,
rule-based knowledge in savants. If we take the
example of harmonic structure in music, we know
that the rules governing key relations are predictable
and invariant and can be acquired by very young
903
children without explicit musical instruction (Sloboda, 1985). If, in intellectual impairment and in
autism, implicit learning is largely spared, and the
highly structured nature of savant domains makes
them optimally amenable to implicit learning, it may
be that mechanisms involved in knowledge acquisition in these domains do not distinguish intellectually impaired from normally developing groups and
no special explanation for these skills needs to be
invoked. However, it also seems unlikely that differences between savants and similarly talented normally developing individuals, at both cognitive and
behavioural levels, will not exert some qualitative
influence on manifested talent. An important research question concerns the high preponderance of
autistic individuals in savant samples. Therefore, in
the following sections, theoretical models of the
savant syndrome will be outlined and evaluated
within the context of our current understanding of
cognitive characteristics well documented in autistic
spectrum disorders.
Autism and savants: cognitive
neuropsychological accounts
Psychological accounts of autism, such as the executive function (Russell, 1997) and theory of mind
(Baron-Cohen, Tager-Flusberg, & Cohen, 2000) hypotheses, have historically focused upon and addressed deficits observed in these individuals.
However, one notable exception to this trend, Weak
Central Coherence theory (WCC) (Frith, 1989; Happé, 1999), directly addresses the question of why
splinter and savant skills should preferentially
emerge in autism. WCC proposes that autism is
characterised by a cognitive style that biases processing in favour of local features over global, context-dependent meaning or Gestalt (Happé, 1999)
and predicts that enhanced performance will be
found on tasks where good featural processing conveys an advantage. In line with these predictions,
Heaton, Hermelin, and Pring (1998), Heavey et al.
(1999) and Hermelin (2001) have argued that a tendency towards featural processing can be advantageous to savants at the early stages of knowledge
acquisition as it facilitates accurate memory for the
individual elements upon which increasingly highly
structured information is based.
Studies into visual perception have shown that
people with autism have increased sensitivity to
unique features in visual stimuli, but difficulties in
recognising shared features between stimuli (Plaisted, O’Riordan, & Baron-Cohen, 1998). Therefore,
Plaisted (2001) has hypothesised that difficulties in
perceiving shared features between stimuli result in
deficient categorisation and generalisation, both
commonly observed phenomena in autism. However,
the extent to which such problems are evident within
savant domains has yet to be demonstrated.
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Pamela Heaton and Gregory L. Wallace
Experimental evidence has shown that non-savant
children with autism are as able as normally developing children to categorise music into major and
minor modes (Heaton, Hermelin, & Pring, 1999) and
musical savants demonstrate an ability to generalise
melodies when they transpose them from one key to
another (Miller, 1989). Similarly, calendar-calculating savants are able to generalise knowledge about
corresponding months and years when generating
dates in the future (Heavey, 1997). However, given
the difficulty of knowing how such terms can be
operationalised within savant domains, the existence of such deficits remains unproved.
Another promising and early perceptual-level account for special skills was put forward by Waterhouse (1988). Her ideas arose in response to the
failure of theoretical models of intelligence to account for these special skills. Importantly, Waterhouse proposed that special cognitive talents and
abilities in savants are qualitatively different from
those of typical individuals. She believed that they
were separate in source from human intelligence and
therefore did not represent end points of the normal
distribution of various skill areas. Specifically, she
proposed that special skills derive from a preconscious and specific set of memory and processing
mechanisms that facilitate ‘acutely accurate and
extremely extensive representation of visual images
and sounds’ and allow ‘the rapid recognition and
facile manipulation of patterns involving those visual
and auditory representations’ (Waterhouse, 1988).
According to the model, the savant may both generate and elaborate upon these complex mental representations, but also see or hear complex patterns
embedded within relevant visual or auditory stimuli.
Similar to our argument, Waterhouse highlights the
importance of the induction of regularities or of
structural elements within various perceptual systems by savants. According to Waterhouse, special
skill development is genetically driven and brainbased, via cortical rededication. Presumably, for
special skills in the context of autism, areas of cortex
(or significant portions of these areas) usually devoted to social functioning would be reallocated to
perceptual pattern recognition. Consequently, this
functional rededication would result in superior
performance on perceptual pattern recognition tasks
and correspondingly poor performance on tasks of
social cognition.
During the same time frame, Treffert (1989) also
proposed a neurologically mediated multi-factor
model of savant skills. Brain-based factors include
compensatory right-hemisphere functioning after
left-hemisphere damage and reliance upon lowerlevel procedural memory due to damage to higherlevel (e.g., semantic) memory circuitry. The
effortless, automatic nature of savant skills and the
intact aspects of memory functioning are noted and
proposed to be necessary but not sufficient for savant skill development. Treffert also notes the
restricted range of savant talent domains and utilises the results of various neuropsychological
studies to demonstrate that these skills are mediated
(at least to a significant degree) by the right hemisphere. Thus the importance of the nature of, and
commonality between, these domains is highlighted.
An additional element to this model is the focus upon
the single-mindedness of savants for the skill area in
question. Thus concentration, repetition, and practice are considered to be important and reinforcing
for the maintenance and elaboration of skills. In an
attempt to explain the preponderance of savant skills
in autism, Treffert drew on research suggesting that
right-hemisphere functioning, at least as relevant to
savant domains, and procedural memory are generally intact in autism. However, importantly, Treffert
makes a clear demarcation in his model by requiring
that the action of genetic factors are reserved for only
the most exceptional, i.e., prodigious, savants.
Therefore, whilst there are multiple paths to the end
points of splinter skill or talented-level savant skill
expression, one does not reach prodigious levels of
performance without a significant genetic predisposition.
In the most recent theoretical account of savant
skill development, Mottron and Burack (2001) have
outlined a model proposing enhanced perceptual
functioning in autism. According to this model,
lower- and higher-level processing mechanisms are
dichotomously grouped, with low-level mechanisms
being domain specific and neurally specified and
higher-level mechanisms being domain general and
distributed across several brain regions. These authors suggest that people with autism show overdevelopment of low-level perceptual abilities at the
cost of high-level processing mechanisms. Thus, it is
postulated that autistic splinter and savant skills
will involve operations that are largely perceptual,
with the proviso that they can include different
modalities or the simple operations of associating,
combining and matching on tracks of visual or
auditory stimuli. A major strength of this model is
that it takes a developmental approach, whereby an
early, unspecified cognitive deficit results in an enhanced cognitive operation via compensatory action.
This subsequently improved aspect of cognitive
functioning becomes increasingly over-trained and
heavily researched, leading to the development of a
restricted interest. Moreover, citing the example of
excellent spatial orientation in autism, these authors
conclude that their model has distinct advantages
over WCC theory since this domain of functioning
does not on the surface require featural processing.
In summary, the savant theories proposed by
Waterhouse, Treffert and Mottron and Burack all
highlight highly efficient computational abilities
operating on domain-specific material. However,
Birbaumer (1999) and his colleagues (Pauli, Lutzenberger, Birbaumer, Rickard, & Bourne, 1996)
have shown that arithmetic calculation becomes
Annotation: The savant syndrome
automatically and rapidly processed in typical individuals as a result of extensive practice. Thus,
according to some accounts, savant skill is simply
one outcome of over-training or practice (Ericsson &
Faivre, 1988). However, a major limitation of measuring outcome is that it fails to provide insights into
the question of whether an innate facility (talent) for
working with specific types of domain-relevant information contributes to savant skill development.
Furthermore, despite its obvious strengths, Mottron and Burack’s proposal that savant abilities
never include aspects of relative weakness among
persons with autism fails to account for several
individuals described in the savant literature. For
example, Smith and Tsimpli (1995) have described
one savant who shows outstanding foreign language
acquisition abilities, and Dowker et al. (1996) have
described a savant poet. There are also examples of
autistic savants who are very sensitive to the
affective dimensions within their talent domain. For
example, Richard Wawro, the savant artist described
by Hermelin, Pring, Buhler, Wolff, and Heaton
(1999), is very sensitive to colour, and in his compositions he changes and intensifies colours in order
to manipulate overall mood. It may then be the case
that language and affect processing deficits, characteristic of autism, exert less influence within savant domains. The question of domain-specific
sparing of affect perception will be further discussed.
A striking weakness in many theoretical accounts
of savants is that they fail to allow for the wide
variation in manifested ability in savants. Although
Treffert highlighted variations in talent in his model,
the evaluation of output (music/art) by individuals
with sufficient expertise within the relevant savant
domains is rarely carried out, and reliable qualitative
data on manifested talent is not available. In line
with Treffert, we propose that splinter skills, talented
and prodigious levels of talent can be identified, and
further suggest that the genesis of such abilities can
also be distinguished. As previously suggested, we
believe that splinter skills arise as a function of the
cognitive style characteristic of autism (Happé,
1999). Thus skills dependent on good visual and
auditory discrimination will be fairly common in
autism. As this information processing style will also
characterise cognition in talented and prodigious
savants, they may develop splinter skills in areas
outside of their talent domains. For example, the
savant artists Stephen and Claudia both possess
outstanding pitch discrimination and memory abilities. However, we propose that within their talent
domains savants will differ from individuals with
splinter skills in several important ways. First, they
will show a highly focused interest in a specific area,
for example, music, art or number. Second, they will
demonstrate an ability to manipulate domainspecific information in order to generate their own
output. Thus, whilst a good memory for dates,
905
commonly seen in autism, would constitute a
splinter skill, a talented savant will have acquired
calendar knowledge which can be extrapolated to the
past and the future. Taking the example of music,
Heaton et al. (1999) reported the case of an adolescent with Asperger syndrome and exceptional
musical splinter skills. On tasks of pitch, interval
and contour discrimination the subject’s performance scores were frequently at ceiling. However, he
had not developed skills for musical performance,
and though his abilities were outstanding, they were
perceptual and analytic in nature.
We propose that differences between talented and
prodigious savants are reflected in qualitative differences in output, the identification of which
necessitates cross-disciplinary collaboration. When
specialist evaluations of savant output are carried
out, for example when Sir Hugh Casson examined
the work of the savant artist Stephen Wiltshire,
prodigious talent is sometimes identified. We therefore suggest that the superiority of prodigious savants is a result of inherent talent, dependent upon
genetic factors.
The notion of talent as a psychological and scientific construct has been the subject of considerable
debate (Howe, Davidson, & Sloboda, 1998). However, Simonton (2001) has recently proposed an
emergenic-epigenetic model of talent development
that we believe provides a useful framework for theorising about the savant syndrome. According to this
model, talent is not contingent upon a single trait but
depends on cognitive, dispositional, physical and
physiological components which operate in a multiplicative way to facilitate the manifestation of
superior expertise within domains. Talent domains
can make simple or complex demands, thereby
varying in the number of essential components
needed for talent realisation. Thus, whilst physical
and physiological components will be far less
important for the development of calendar or
numerical skill than for piano playing, cognitive and
dispositional components may make similar demands across music and number domains. A major
strength of this model, when applied to savants, is
that it is able to account for the observed variations
in levels of talent manifestation. Specifically, these
relate to levels of development, under genetic control,
of specific talent components and the interactions
between them. Furthermore, the model also allows
for heterogeneity among skill profiles that result in
similar levels of overall talent manifestation. So
whilst the savant artist Stephen (Hermelin, 2001)
demonstrates a good sense of form and detail,
Richard (Hermelin et al., 1999; Hermelin, 2001)
shows strengths in the creative use of colour. We
therefore subscribe to Simonton’s talent model and
propose that whilst preserved or enhanced perceptual/cognitive mechanisms are necessary conditions
for certain types of savant talent realisation, they are
not in themselves sufficient for it.
906
Pamela Heaton and Gregory L. Wallace
Deficits in executive functions have been documented in autistic savants (Steel, Gorman, & Flexman, 1984; Rumsey, Mannheim, Aquino, Gordon, &
Hibbs, 1992; Mottron, Peretz, Belleville, & Rouleau,
1999); however, there is an obvious confound as to
the specificity of the executive dysfunction. Unfortunately, from the limited evidence, it is unclear as to
whether the executive dysfunction is the result of the
presence of an autistic spectrum disorder, in which
executive functioning is a robustly documented
deficit (e.g., Ozonoff, 1995; Rumsey & Hamburger,
1988), or whether it is integral to the cognitive
landscape of the savant syndrome. Generativity or
fluency is one subdomain of executive functioning,
which has been demonstrated as deficient in autistic
spectrum disorders (Dunn, Gomes, & Sebastian,
1996; Turner, 1999). However, consistent with the
ideas of limitations for measuring cognitive mechanisms, valid assessment of executive functioning,
particularly generativity, requires both domainspecific and domain-general assessment. Of relevance here are studies by Ryder, Pring, and Hermelin
(1999) comparing autistic savant artists to control
groups of normal art students, individuals with
autism and those with moderate learning difficulties.
Findings from these studies demonstrate that on
tasks of design fluency and visual synthesis, autistic
savants showed as severe a fluency deficit as nonsavant autistic controls. However, on the Torrence
Test of Creative Thinking the output of the autistic
savants was more elaborate than that of the two IQmatched control groups (individuals with autism
and those with moderate learning difficulties), and
on the visual synthesis task originality scores
equalled those of gifted art students. Thus, whilst
these autistic savants showed a pervasive fluency
deficit characteristic of autism, they were nevertheless able to produce highly elaborated and original
responses within their talent domain.
Affect perception, savants and autism
Whilst a lack of expressiveness in music and art productions has sometimes been reported in savants
(O’Connell, 1974), this is certainly not always the case
(Selfe, 1977; Miller, 1989; Hermelin et al., 1999). Both
early and recent accounts of autism (Kanner, 1943;
Hobson, 1989) have proposed core affective and
interpersonal deficits in autism. Children with autism
often show difficulties in understanding social emotions (e.g., pride and embarrassment), although they
report personal experiences of emotions as frequently
as normally developing children and are also able to
understand the primary emotions of happiness and
sadness (see chapter by Kasari, Chamberlain, &
Bauminger, 2001). The savant domains of music and
art are rich in affective content and questions
regarding the extent to which affect processing difficulties characteristic of autism generalise into these
domains is important in the current context. A recent
study (Heaton, Happé, Williams, & Cummins, 2003)
attempted to cast some light on this question. In this
study, non-savant children with autism were required
to match excerpts of orchestral pieces to visual images
depicting the affective categories of love, triumph, fear
and anger. The results showed that low-functioning
children with autism performed as well as normally
developing children matched for verbal mental age
and high-functioning children with autism performed
at levels that were consistent with chronological age.
Correlations between scores for music/emotion
identification and a task of social emotion identification (Baron-Cohen, Wheelwright, Scahill, Lawson, &
Spong, 2001) were non-significant. Given that the
limited research to date provides more evidence for
domain-specific sparing than for a domain-general
deficit, it cannot be assumed that affect processing
difficulties in interpersonal and social domains
necessarily generalise into the savant talent domains
of music and art.
Obsessions and restricted interests
By definition, individuals with autism show obsessive and restricted interests (APA, 1994). Whilst this
tendency to engage in repetitive activity in narrowly
focused areas is generally disadvantageous for
people with autism, in that it gives rise to a restricted repertoire of behaviour and experience, this may
not always be the case. For example, if this tendency
co-occurs with other cognitive, emotional and/or
physical talent components, it may serve to function
as a motivational trait (Simonton, 2001), thereby
enhancing the probability of talent emergence.
Asperger (1991), who along with Kanner (1943) first
described the autistic disorder, proposed that the
personality characteristics exhibited by his patients
could facilitate high-level skill development. Indeed,
one of Asperger’s patients was a successful composer. Several lines of evidence support the view
that obsessions and restricted interests might play a
role in the development of savant talent. First, although individuals with autism represent a relatively small proportion of the cognitively impaired
population, the majority of talented, but cognitively
impaired individuals have been diagnosed with
autism. Second, in cases where savant talents are
reported in individuals without autism, they frequently have developmental or acquired disorders
that include obsessive behaviours and/or restricted
interests as clinical features (e.g., Tourette’s syndrome and frontotemporal dementia). Finally, mild
autistic features have been noted in some professional groups, for example musicians with absolute
pitch (Brown et al., 2003), who are noted for high
achievement. Therefore, converging evidence highlights the significance of obsessive and restrictive
interests in the development of savant talent, both in
Annotation: The savant syndrome
and out of the context of autistic spectrum disorders.
The presence of savant skills in other groups
Traditionally, specific disorders/conditions associated with savant skills have been limited to autistic
spectrum disorders and visual impairment. However, other disorders have been noted to co-occur
with unexpected skills and they too may inform our
understanding of the savant syndrome. For example,
DeLong and Aldershof (1988) described a group of
clinically referred children with manic-depressive
illness and special skills. Although the group included children with average to above-average intelligence, they all exhibited autistic-like symptoms,
with repetitive and obsessive-compulsive behaviours
being most common. This behavioural expression
stands in stark contrast to the nonsavant manicdepressive children in their sample who did not
demonstrate such tendencies. Although savant skills
in individuals with this disorder have not been
widely reported in the extant literature, support for
this co-occurrence derives from the long and continuing history documenting manic-depressive disorder in adults with exceptional creative talents (e.g.,
Andreasen, 1987).
Another disorder occasionally mentioned in the
savant literature is Gilles de la Tourette’s Syndrome
(GTS), a neurodevelopmental disorder resulting in a
variety of tics and/or echolalia and coprolalia. Significantly, autism is more prevalent in GTS than
would be expected from population base rates alone
(Baron-Cohen, Mortimore, Moriarty, Izaguirre, &
Robertson, 1999). Thus, it is not surprising that a
number of savant case studies document the presence of GTS (e.g., Nelson & Pribor, 1993), sometimes
without a diagnosis of autism, but with the shared
traits that may be important for the development of
savant skills (e.g., obsessive-compulsive behaviours/tendencies). There is at least one recorded
case of a calendar-calculating savant with GTS
(Moriarty, Ring, & Robertson, 1993) who does not
appear to show behaviours associated with autism.
However, given that this case was described before
the widespread recognition of Asperger syndrome,
and that detailed clinical data are not provided, it is
difficult to rule out any autistic-like tendencies.
A striking development, which may have pertinence to understanding savant skills, is the documentation of multiple cases of emerging and/or
preserved artistic and other skills in the context of
dementia (Miller, Ponton, Benson, Cummings, &
Mena, 1996; Miller et al., 1998). Unlike the previously provided examples of developmental disorders,
these unexpected skills occur in the presence of an
adult-onset disorder, frontotemporal dementia
(FTD). This particular type of dementia is a progressively degenerative disorder isolated to the
907
anterior temporal and prefrontal neuroanatomical
regions, resulting in dramatic behavioural changes,
the most characteristic of which are social in nature.
Expression of these social deficits can be quite variable, from frank antisocial behaviour to a lack of
social awareness and empathy. Other symptoms
may include hyperorality, stereotypies, extreme distractibility, or obsessive-compulsive behaviours.
As the dementia progresses, these individuals’
interest in their skill area becomes increasingly
restricted. Social, cognitive, and adaptive skills
deteriorate simultaneously, resulting in negligence
of occupational and personal responsibilities in favour of focus on the skill area (Miller, Boone, Cummings, Read, & Mishkin, 2000). Moreover, the
cognitive style of these individuals reflects an
increasing interest in the details of various auditory
and visual stimuli. Importantly, the abovementioned attributes bring to mind characteristics of
autistic spectrum disorders, particularly their preponderance for restricted interests (APA, 1994) and
for a featurally biased information processing style
(Happé, 1999).
Individuals with savant skills who have been
diagnosed with the diverse set of disorders described
above clearly show cognitive features and behavioural traits characteristic of autism. We thus conclude that these traits are crucially important and
facilitating for savant skill development, both within
and outside of the context of autism.
Summary
In this annotation we have attempted to draw together a variety of experimental findings and theoretical accounts of the savant syndrome. We have
outlined evidence suggesting that the savant syndrome is most closely associated with autism, although we have also considered savant talents in
individuals with other clinical disorders. In order to
accommodate findings of outstanding talents in
autistic individuals without cognitive impairment,
we have proposed that functional impairments may
be contrasted with skills in these cases. In evaluating issues relating to intelligence in savants we have
concluded that global measures of intelligence, derived from standardised IQ tests, fail to provide insight into the savant syndrome. However, specific
cognitive mechanisms, underpinning intelligence
and spared in autism (Anderson, 1998), are proposed to be necessary for skill development in savants. We have briefly reviewed neuropsychological
accounts of autism that provide potentially important insights into information processing in savants,
although we also present evidence suggesting that
deficits in creativity and affect processing characteristic of autism may be less applicable to savants,
particularly within their talent domains. In line with
Treffert (1989), we propose that innate talent is a
908
Pamela Heaton and Gregory L. Wallace
necessary condition for the development of prodigious savant skill. Utilising a model of talent development delineated by Simonton (2001), we propose
that traits predisposing individuals towards highly
focused attention within specific domains facilitate
high-level achievement in those with both developmental and late-onset disorders.
Interest in savants has a long history, stretching
back to the early 18th century; nevertheless, the
savant syndrome remains as much a mystery now as
it did when it was first described. Given that many
questions about the existence and nature of savant
talent remain unanswered, it seems likely that
research efforts will continue unabated.
Correspondence to
Pamela Heaton, Department of Psychology, Goldsmiths College, University of London, New Cross,
London, SE14 6NW, UK; Email: P.Heaton@gold.ac.uk
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Manuscript accepted 31 July 2003