[8] At age 25, Tammet was diagnosed with Asperger syndrome by Simon Baron-Cohen of the University of Cambridge Autism Research Centre.

[10] Tammet was the subject of a documentary film titled Extraordinary People: The Boy with the Incredible Brain,[11] first broadcast on Channel 4 on 23 May 2005.

[16] The site offered language courses (as of 2015, French and Spanish) and had been an approved member of the UK National Grid for Learning since 2006.

[21][22] Allan Snyder, director of the University of Sydney Centre for the Mind, called the work 'an extraordinary and monumental achievement'.

[23] Tammet argues that savant abilities are not "supernatural" but "an outgrowth" of "natural, instinctive ways of thinking about numbers and words".

[30] After the World Memory Championships, Tammet participated in a group study, later published in the New Year 2003 edition of Nature Neuroscience.

They reported that he used "strategies for encoding information with the sole purpose of making it more memorable", and concluded that superior memory was not driven by exceptional intellectual ability or differences in brain structure.

In a further study published in Neurocase in 2008, Baron-Cohen, Bor, and Billington investigated whether Tammet's synaesthesia and Asperger syndrome explained his savant memory abilities.

They concluded that his abilities might be explained by hyperactivity in one brain region (the left prefrontal cortex), which results from his Asperger syndrome and synaesthesia.

[34] Published in Cerebral Cortex (2011), an fMRI study led by Jean-Michel Hupé at the University of Toulouse (France) observed no activation of colour areas in ten synaesthetes.

While accepting that Tammet meets the standard definition of a prodigious savant, Foer suggests that his abilities may simply reflect intensive training using memory techniques, rather than any abnormal psychology or neurology.

[9] Tammet set the European record for reciting pi from memory on 14 March 2004 – recounting to 22,514 digits in five hours and nine minutes.

[41][42][43][44][45][46][47] He revealed in a French talk show on Radio Classique on 29 April 2016, that this event inspired Kate Bush's song "Pi" from her album Aerial.

In Born on a Blue Day, he writes that he knows 10 languages: English, Estonian, Finnish, French, German, Lithuanian, Esperanto, Spanish, Romanian, Icelandic, and Welsh.

[9] In Embracing the Wide Sky, Tammet wrote that he learned conversational Icelandic in a week, and appeared on an interview on Kastljós on RÚV speaking the language.