The motivation for the current research is to understand the condition of savant syndrome in more depth by contrasting a group of autistic savant individuals with a group of autistic individuals who do not have a savant skill. A third group of typical controls without autism or savant skills serve as a comparison. With this approach, we aim to separate features that are tied to savant syndrome from features that are tied to autism per se. We ask what individual differences lie within the autistic population that might allow some to develop savant skills while others do not.
We first summarise current theoretical frameworks on the origins of savant skills. We then present two experiments that consider the development of savant skills at multiple levels of cognition, perception, and behaviour. There is no consensus on exactly how savant skills are developed in autistic individuals.
It could therefore be that their skills develop simply through many hours of extended practice. Savants too appear to require practice, but here we ask exactly why they practice and whether they also have cognitive or perceptual differences beyond practice alone.
Two theoretical models have bridged the gap between need-for-practice and autistic symptoms in savants [ 15 , 16 ]. As a result, these extra resources could be re-allocated to the development of talent by permitting more time i. Since these cognitive resources have been allocated away from monitoring social interactions, a further expected consequence might also be lower social and communication skills in savants and we explore this in experiment 1 below.
In contrast, Simner et al. Tentative support for this comes from LePort et al. However, the controls they tested did not have autism, making it unclear whether obsession was tied to savant skills per se or simply to autism or other co-occurring neurodevelopmental differences [ 20 ].
In addition, they may not have corrected their question-by-question statistics for multiple comparisons, making it difficult to tie their findings to any particular trait. Similarly, Howlin et al. Given these differences across studies in their focus, questionnaire length, and testing groups, it remains unclear whether savants are particularly notable for their obsessional traits, above and beyond what we would expect from autism alone.
Here we test both models described above, i. Although both types of rehearsal from mind-blindness or obsessiveness could influence savant skills, this practice alone probably does not act as the only catalyst for talent to emerge.
There may also be differences in certain cognitive abilities, linked to autism, which manifest themselves more strongly in individuals who acquire savant skills compared to those who do not. Specifically, we propose here and previously [ 16 , 23 ] that talent could emerge from autism traits such as excellent attention-to-detail, hyper-systemising, and sensory differences.
These rules can be found in savant skills such as calendar calculation i. A related proposal is Mottron et al. Some savant skills do indeed depend on mapping regularities across systems e. In addition, savants appear to show a particular cognitive style of enhanced local processing, as outlined in the enhanced perceptual functioning model [ 3 ], and less global interference e. Again, however, it is not clear whether these influences are tied to being a savant or simply having autism. Here we test groups of autistic individuals with and without savant syndrome to examine whether savants have a particular cognitive style e.
Savant talent may also have important sensory components. Baron-Cohen et al. Subjective accounts of sensory irregularities in autism have been shown previously [ 27 , 28 , 29 , 30 ], and multiple studies have objectively demonstrated superior visual, auditory, and tactile sensory perception in autism [ 31 , 32 , 33 , 34 , 35 , 36 ].
These sensory differences may bring about the emergence of talent by affecting information processing at an early stage [ 23 ] although this suggestion is not universally supported [ 22 ]. One final sensory link between autism and savant syndrome is the presence of synaesthesia, where stimuli such as letters, numbers, and sounds invoke automatic and additional sensory experiences such as colours [ 37 , 38 ].
Hughes et al. Simner et al. Elsewhere, we have already supported one branch of this model by showing that people with synaesthesia have elevated skills in savant domains e. Here we test the other branch of the model by examining whether their rehearsal is born out of obsessive traits [ 16 ] or mind-blindness which might predict lower social or communication skills [ 15 ]. Finally, we test the role of sensory sensitivities more generally, by comparing the sensitivities of autistic individuals with and without savant skills.
In our experiments, we look at two groups of autistic individuals, with and without a savant skill specifically, prodigious talents which are above the skills of the general population. In experiment 1, we contrast our groups on cognitive and sensory self-report measures predicted by previous theoretical accounts. In addition to our two groups of autistic individuals, with and without savant skills, we also test a typical control group with neither autism nor prodigious talents.
As stated above, there is very little empirical evidence to evaluate current theories of savant syndrome apart from tentative pointers towards increased obsessionality [ 16 ] and evidence for links to synaesthesia [ 16 , 39 ].
Our goal is to test all theories directly; therefore, our predictions are based on the above theoretical frameworks. Following the theory by Baron-Cohen et al. We also predict they will report a more local as opposed to global cognitive style since this has previously been implicated in e.
Based on the model of autism-linked obsessive rehearsal [ 16 ], we predict that autistic-savants will report more obsessional behaviours compared to autism individuals without a savant skill.
Alternatively, the rehearsal account based on mind-blindness [ 15 ] predicts that autistic savants would have lower social or communication skills here measured using the AQ compared to autistic individuals without a savant skill. Finally, we predict that both autism groups, regardless of the presence of a savant skill, will report heightened traits or behaviours in all of the above areas compared to the typical control group.
Experiment 2 investigates how a distinct psychological or behavioural profile in savants explored in experiment 1 might influence performance on a behavioural task. We test the same three groups, to determine whether savants have a particular style of learning when presented with a novel savant skill: calendar calculation.
As noted above, calendar calculation is the ability to give the correct day of the week for a given date in the past or future e. In experiment 2, three groups of participants autistic-savants, autistic-nonsavants, controls learned how to calendar calculate through a series of tutorials about different patterns and rules of the calendar. It is unclear whether calendar-calculating savants rely on rote memorisation of dates [ 45 ] or internalisation of the inherent rules of the calendar e.
No studies to date have investigated the learning of calendar calculation skills in savants who do not already possess this skill compared to nonsavant autistic individuals and controls; therefore, our predictions below are again based on current theoretical models of savant syndrome. If savant syndrome is linked to pre-existing abilities or dispositions as opposed to practice alone , then we predict that savants may show a superior level of accuracy.
In contrast, accounts of savant skills that emphasise obsession or practice may not predict immediate advantages without extended training but might predict a different learning approach. In summary, our studies investigate savant syndrome by directly contrasting savants against a group of autistic individuals without a savant skill as well as a typical control group.
Our investigation is the first to take an empirical approach to test a number of theoretical accounts of savant syndrome [ 15 , 16 , 23 , 24 , 44 ], some of which currently lack a clear empirical foundation. One hundred and eleven participants took part in the study. Participants were recruited from two sources. Three of the 44 autistic-savants were recruited from The Savant Network, which is a group of individuals with a self-reported savant skill who have expressed an interest in taking part in research studies at the University of Sussex.
All autistic-nonsavant individuals and all controls also came from CARD, which holds status information of both autism and typical participants. To ensure that our autism participants had sufficient cognitive levels to independently provide consent, we sent our recruitment materials to high functioning autistic adults, as detailed in the CARD database of autistic participants.
Participants volunteered to take part in our study in response to an email advertisement that was sent to participants in these databases autistic-savants, autistic-nonsavants, and typical adults. Participants did not receive payment for taking part, and our study was approved through the Cross-Schools Science and Technology Research Ethics Committee at the University of Sussex.
These formal diagnoses had also been recorded for 77 of the 80 autistic individuals as part of their CARD recruitment procedure.
There were no controls who reported autism. All autistic-savants, and no other group, self-reported having a savant skill in our Sussex Savant Questionnaire ; see below. These are described below.
This questionnaire was created for the purposes of this study. The AQ contains 50 items to measure autistic traits in adults of average or above average intelligence [ 43 ].
The AQ contains 10 statements for each of five different subscales: social skills, attention switching, attention-to-detail, imagination, and communication. Participants responded to each statement on a four-point scale definitely agree, slightly agree, slightly disagree, definitely disagree.
Approximately half of the questions are reverse coded. Responses were coded as 0 or 1, with total scores ranging from 0 to Items were given a score of one point if the participant recorded an autistic trait e.
A total score of 32 or above is used is a strong indicator of likely autism [ 43 ]. The SQ-R contains 75 items with possible scores ranging from 0 to , where a higher score suggests a greater tendency to systemise. Systemising is defined as the drive to identify and analyse systematic relationships or patterns in rule-based information.
Participants demonstrated their level of agreement with each statement using a four-point scale definitely agree, slightly agree, slightly disagree, definitely disagree. The questionnaire measures sensory sensitivity across seven modalities that include visual, olfactory, auditory, gustatory, tactile, vestibular, and proprioception. Each of these modalities is represented by six items in the questionnaire, and this is further broken down into three items each in order to measure both hypo-sensitivity and hyper-sensitivity per modality.
Each question has one of five answers strongly disagree, disagree, neither agree nor disagree, agree, strongly agree. Reverse scored questions for this factor indicate more attention-to-detail or a local processing preference e. All participants were tested remotely via the online survey-hosting platform Qualtrics www.
Participants autistic-savants, autistic-nonsavants, and controls accessed the study by clicking on a URL provided to them electronically. For those participants recruited from the CARD database, the AQ and SQ-R data were collected in a separate procedure as part of the standard protocol for participants when signing up to that database.
In this, participants completed the AQ and SQ-R among other tests online during the sign-up stage of recruitment. Our procedure took approximately 20 min to complete, and participants were also asked a set of additional questions for publication elsewhere concerning synaesthesia. Since some participants completed different elements of our tasks e. All data here and throughout approximated normal distributions and so parametric statistics were used.
AQ data was collected from 33 autistic-savants, 30 autistic-nonsavants, and 28 controls, and Fig. Where we found null results between autistic-savants and autistic-nonsavants for the AQ, we calculated Bayes factors to determine whether null results indicated no difference or a lack of statistical power. Footnote 1 We selected an informed prior i. This comparison was chosen because we are looking to see whether differences truly exist between our autistic-savants and autistic-nonsavants.
Our Bayes factors suggested support for the null hypothesis i. Refer to Additional file 1 for more information regarding our calculation of the above Bayes factors including our choice of parameters as well as a sensitivity analysis.
SQ-R data was collected for 31 autistic-savants, 33 autistic-nonsavants, and 27 controls, and their data is shown in Fig. All participants completed this test. Figure 5 shows all factors of the SCSQ. As before, we calculated Bayes factors to determine whether these null results indicated no difference or a lack of statistical power. This time, however, no suitable previous studies exist from which to draw informed priors. We therefore used an uninformative prior with the H1 prior distribution modelled as a uniform distribution in which all effects within a specified interval are considered equally likely given no previous evidence to inform our decision.
Following the standard procedure, we entered the lowest and highest possible mean differences between groups i. In summary, we found that autistic individuals, irrespective of savant syndrome, scored higher than controls on need for organisation, systemising, and local bias i. Figure 6 shows all factors of the LOI across groups.
We also found that seven autistic-savants as well as two autistic-nonsavants and one control scored above the threshold of a score of 20 or more which suggests obsessive-compulsive disorder OCD symptoms.
All participants completed this test, whose aim had been to separate our autism sample into our two autism sub-groups autistic-savants and autistic-nonsavants.
Table 1 shows the categories of skills asked about during the study along with the number of cases of each skill reported by participants.
For completeness, the Additional file 2 contain descriptive statistics for the various sub-scales of our above questionnaire measures broken down according to the presence or absence of particular savant skills, but we do not consider them in detail here due to the large number of measures and lack of power when smaller samples are divided in this way. As an additional validation of our methodology, we looked again at the skills reported in Table 1 , to see whether these self-reports could be directly tied to our measures.
Finally, we note that there were gender imbalances across our groups see [ 46 ] for gender effects in autism. For an exploration of the effects of gender on all of our above measures, see footnote. Footnote 2. Our results reveal a distinct profile of group differences between autistic-savants and autistic-nonsavants.
In all instances, these traits are features of autism more generally i. However, it is not the case that savants are simply shifted upwards along the autism spectrum. We did not find any differences between autistic-savants and autistic-nonsavants on the AQ or on subscales relating to attention-to-detail or social and communication skills, which might otherwise have been expected based on previous theoretical accounts [ 15 , 23 ].
The purpose of experiment 2 was to explore whether participants could be trained to perform a characteristic savant skill—calendar calculation—and to investigate whether autistic-savants would show differences in accuracy or learning-style compared to autistic-nonsavants.
As before, controls without autism or savant skills were included to separate effects linked to autism from effects linked to savant syndrome. Participants learned a number of different calendar rules throughout a training session and were given a final test that tapped all the rules.
Savants who have calendar calculating within their repertoire are already sensitive to these rules [ 47 ]. As well as examining the overall ability to learn the task, we can use this pattern of response times i.
In summary, this study aimed to determine whether people with savant skills have a natural aptitude for learning this kind of information or whether they approach the task with different strategies. If so, we assess whether this is linked to autism per se or linked only to those autism subjects with pre-existing savant abilities excluding calendar calculation. Fifty-eight participants took part in experiment 2, 14 of whom also took part in experiment 1 above 6 autistic-savants, 6 autistic-nonsavants, and 2 controls.
The participants comprised 13 autistic-savants 4 female; mean age All autistic-savants, and no other group, self-reported having a savant skill. Forty-two participants were recruited from CARD 13 autistic-savants, 10 autistic-nonsavants, 19 controls.
The remaining 16 participants all controls were recruited from the University of Sussex community. In addition to the above participants, a further 22 were initially recruited but later excluded. These were 13 participants who used incorrect response buttons i. Three of these had response times that were not within a feasible range i. All participants received an initial email invitation and accessed the study by clicking on a link embedded in the email that took them to the information and consent page.
Participants then gave demographic information and next completed the Sussex Savant Questionnaire SSQ in the same way as in experiment 1 above. Participants then completed additional questionnaires to be published elsewhere involving synaesthesia.
What causes savant syndrome? 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 persons 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 persons 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 75 prodigious savants living worldwide at the present time who would meet this high threshold of special skill. What are typical savant skills? Musical Talent. Artistic Talent. Calendar Calculating. Other Skills. Find Savant Syndrome Library Resources. Enter your location to receive information about nearby SSM Health services. My location is: Why do we ask? Studies in human inheritance. Human Biology, 3 , — Rimland, B. Inside the mind of the autistic savant.
Psychology Today, 12 , 68— Idiot savants. Wortis Ed. New York: Plenum Press. Seashore, C. The psychology of music. New York: McGraw-Hill. Sloboda, J. Musical expertise. An exceptional musical memory. Musical Perception, 3 , — Spitz, H. The digit span of idiot savants. American Journal of Mental Deficiency, 78 , — Steel, J. Neuropsychiatric testing in an autistic mathematical idiot-savant: Evidence for non-verbal abstract capacity.
Journal of American Academy of Child Psychiatry, 23 , — Takeuchi, A. Psychological Bulletin, , — Thaut, M. Measuring musical responsiveness in autistic children: A comparative analysis of improvised musical tone sequences of autistic, normal, and mentally retarded individuals.
Journal of Autism and Developmental Disorders, 18 , — Thorndike, L. Stanford-Binet Intelligence Scale 4th ed. Chicago: Riverside Publishing Co. Torrance, E. Torrance Tests of Creative Thinking. Personnel Press Inc. Tredgold, A. A textbook of mental deficiency 9th ed. Treffert, D. Extraordinary people. London: Bantam. Viscott, D. A musical idiot-savant. A psychodynamic study and some speculations on the creative process. Psychiatry, 33 , — Wechsler, D.
Wechsler Intelligence Scale for Children-Revised. New York: Psychological Corp. Wechsler Adult Intelligence Scale-Revised. Wechsler Memory Scales-Revised. Wetherill, R. Sequential estimation of points on a psychometric function. British Journal of Mathematical and Statistical Psychology, 18 , 1— Download references. You can also search for this author in PubMed Google Scholar.
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