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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This Issue

Philosophical Transactions of the Royal Society B: Biological Sciences cover image

27 May 2009

Volume 364Issue 1522

Discussion Meeting Issue ‘Autism and talent’ organized by Francesca Happé and Uta Frith

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DOI:https://doi.org/10.1098/rstb.2008.0323
PubMed:19528025
Published by:Royal Society
Print ISSN:0962-8436
Online ISSN:1471-2970

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Published online27/05/2009
Published in print27/05/2009

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