A Further Account of the Idiots Savants, Experts with the Calendar

Horwitz, William A.; Deming, W. Edwards; Winter, Robert F.

doi:10.1176/ajp.126.3.412

Cited by 31 publications

(40 citation statements)

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“…When Great Britain adopted the Gregorian calendar in 1752, the days between 3 and 13 September did not happen, a cause of some civil unrest. False extrapolations of the Gregorian calendar to years before 1752 were made by George (Horwitz et al 1969) and MW (Cowan et al 2003). GC assumed that 1700 was a leap year but was ignorant of the omission of days in 1752 (Cowan et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Do calendrical savants use calculation to answer date questions? A functional magnetic resonance imaging study

Cowan

Frith

2009

Phil. Trans. R. Soc. B

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Calendrical savants can name the weekdays for dates from different years with remarkable speed and accuracy. Whether calculation rather than just memory is involved is disputed. Grounds for doubting whether they can calculate are reviewed and criteria for attributing date calculation skills to them are discussed. At least some calendrical savants possess date calculation skills. A behavioural characteristic observed in many calendrical savants is increased response time for questions about more remote years. This may be because more remote years require more calculation or because closer years are more practised. An experiment is reported that used functional magnetic resonance imaging to attempt to discriminate between these explanations. Only two savants could be scanned and excessive head movement corrupted one savant's mental arithmetic data. Nevertheless, there was increased parietal activation during both mental arithmetic and date questions and this region showed increased activity with more remote dates. These results suggest that the calendrical skills observed in savants result from intensive practice with calculations used in solving mental arithmetic problems. The mystery is not how they solve these problems, but why.

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Section: Introductionmentioning

confidence: 99%

Do calendrical savants use calculation to answer date questions? A functional magnetic resonance imaging study

Cowan

Frith

2009

Phil. Trans. R. Soc. B

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“…A repeated-measures ANOVA with yearly intervals (28, 11, or 17) as the within-group factor revealed there to be a significant effect of interval on mean recall (F (2,12) =21.58; p<0.001). Planned linear contrast analysis showed a superior mean recall for the 28-year list (mean 6.29, SD 2.21) when compared with the control lists combined (F (1,6) =46.50, p<0.001; 11y mean 4.00, SD 2.00; 17y mean 4.14, SD 1.34).…”

Section: Resultsmentioning

confidence: 96%

“…1 Calculation spans vary, but have been reported to be up to 40 000 years in range. 2 Calendar calculation is often associated with autism spectrum disorder (ASD), 3 but is also seen in those with non-specific learning disabilities* 4 and in individuals who have undergone brain surgery. 5 It is rarely observed in the typically developing population.…”

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confidence: 99%

The structure of savant calendrical knowledge

Heavey

Hermelin

Crane

et al. 2012

Develop Med Child Neuro

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ASD Autism spectrum disorderAIM We aimed to explore the organization of the calendar knowledge base underlying date calculation by assessing the ability of savant calendar calculators to free recall a series of date lists.METHOD Four experiments are reported that assessed recall of structural and non-structural features of the calendar in eight savant calendar calculators (seven males; one female; median age 34y 6mo; age range 27-47y), five of whom had a diagnosis on the autism spectrum. The inclusion criterion was a genuine calculation ability rather than an interest in dates.RESULTS Mean recall was facilitated for material organized according to the structural features of a calendar (leap years, dates falling on the same weekday, dates occurring at 28y intervals) but not for a non-structural calendar feature (Easter Sunday).INTERPRETATION Distinctions are drawn between two sources of savant calendar-related knowledge, structural and event related. It has been suggested that structural knowledge plays a key role in the acquisition and operation of savant date calculation skills.Savant calendar calculators can name the day of the week of past or future dates at speed, often in the presence of considerable intellectual impairment.1 Calculation spans vary, but have been reported to be up to 40 000 years in range.2 Calendar calculation is often associated with autism spectrum disorder (ASD), 3 but is also seen in those with non-specific learning disabilities* 4 and in individuals who have undergone brain surgery. 5 It is rarely observed in the typically developing population. 6 There is debate as to how this unusual skill develops. Rote memorization of the calendar, based on extensive practice, is often suggested. 7,8 For some savants, memorization may extend to learning the 14 calendar templates featured in perpetual calendars 9 or the use of anchor ⁄ benchmark dates. 10Indeed, functional magnetic resonance imaging has shown savant calculation to involve brain circuitry that is typically activated by memory retrieval tasks, albeit in a single case study. 11The finding that savant calculation spans can exceed the range of perpetual calendars strongly suggests that processes beyond rote memorization must be involved, perhaps in relation to calendar structure. 1 The calendar is characterized by many internal regularities, for example corresponding month structures within the same year and 28-year and 400-year cyclical repetitions. The systematic study of response times to date questions has revealed that some savants use these regularities in performing their calculation. 1,12 The suggestion that date calculation does involve at least some calculation processes is consistent with recent functional magnetic resonance imaging data from an individual with ASD who showed similar patterns of parietal activation during both calendar calculation and mental arithmetic. 13 Despite evidence for the use of calendar rules, it is notable that few savants are able to explicitly state these rules and regularities. 14 Although memor...

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“…Dase, who did calculations for Gauss and Schumacher, was "unable to comprehend the first elements of mathematics." One pair of twins with prodigious abilities for calendrical calculation were estimated to have IQs in the 60s and had great difficulties with simple arithmetic (Horwitz, Deming, & Winter, 1969). Mitchell (1907) noted that two prodigious calculators, Fuller (1710Fuller ( ?-1790 and Buxton (1702Buxton ( -1772, "were men of such limited intelligence that they could comprehend scarcely anything, either theoretical or practical, more complex than counting" (pp.…”

Section: Intelligencementioning

confidence: 99%

Mathematical Expertise

Butterworth¹

2006

The Cambridge Handbook of Expertise and Expert Performance

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A Further Account of the Idiots Savants, Experts with the Calendar

Cited by 31 publications

References 1 publication

Do calendrical savants use calculation to answer date questions? A functional magnetic resonance imaging study

Do calendrical savants use calculation to answer date questions? A functional magnetic resonance imaging study

The structure of savant calendrical knowledge

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