Tammet has been "studied repeatedly" by researchers in Britain and the United States, and has been the subject of several peer-reviewed scientific papers.Professor Allan Snyder at the Australian National University has said of Tammet: "Savants can't usually tell us how they do what they do. It just comes to them. Daniel can describe what he sees in his head. That's why he's exciting. He could be the 'Rosetta Stone'
to science." In his mind, he says, each positive integer up to 10,000 has its own unique shape, colour, texture and feel. He has described his visual image of 289 as particularly ugly, 333 as particularly attractive, and pi as beautiful. The number 6 apparently has no distinct image yet what he describes as an almost small nothingness, opposite to the number 9 which he calls large and towering. Tammet has described 25 as energetic and the "kind of number you would invite to a party". In his memoir, Tammet states experiencing a synaesthetic and emotional response for words and numbers, but not letters in algebraic contexts.
Tammet holds the European record for reciting pi from memory to 22,514 digits in five hours and nine minutes on 14 March 2004. Tammet has reportedly learned 10 languages, including Romanian, Gaelic, Welsh, and Icelandic which he learned in a week for a TV documentary.