Autistic savant Daniel Tammet wrote this gem, and yes that means he has ‘rainman' like mental skills. In fact, he learnt Icelandic (his 11th language) in the week prior to being interviewed for an Icelandic television program.
Tammet takes us on a surprisingly entertaining journey through the current research on how our brains operate - how they remember, how they learn language, logic and mathematics. He proposes a very simple overarching theory about our brain functionality which can ultimately explain déjà vue, memory distortion, information overload, the difficulty learning a second language (there’s no reason to believe it gets harder with age, but only our first language is stored in the ‘language area’ of the brain, while second languages are stored elsewhere), why words, phrases or physical settings prompt unconscious memory retrieval associated with that stimulus (for example, why moving students form one classroom where they learned material to another for examinations has a negative impact one their ability to recall what they’ve learned), and why the typical English speaking adult can remember the meanings of more than 45,000 words.
His theory starts by debunking absolutely the idea that our brains work like computers – that we store and retrieve memories and use some kind of software to manage the data. Our brains are instead a simple instrument that uses in-built pattern recognition to re-create memories each time they are 'retrieved' - there is not memory bank to speak of. This pattern recognition system is a variant on Noam Chomsky’s theory that the brain has a built in system of grammar, and that a rules can allow a brain to quickly learn any language (as all languages conform to the basic rules of grammar in the human brain). The problem of course is that repeatedly re-creating memories can lead to an actual creation of something entirely new. I will never trust eyewitness evidence again.
These in built ‘grammatical’ rules even allow us to perform complex mathematics. Tammet explains his own mathematical ability as simply applying the grammar of mathematics. He sees a number and gets a feeling if it is prime, just as we see a new work for the first time and know, due to the pattern of letters, whether it could be a real english word, and possibly induce its meaning. We know instinctively that qwrsh is not a word, just like Tammet knows that 12391 is prime.
He compares the beauty of our built in system of information arrangement and recreation to the dewey decimal system:
Dewey's system is a marvel of organization, but I have given detailed examples here in order to make an important philosophical as well as practical point. Information is meaningless unless it can be made sense of, and to do that it requires an internal system of thought and ideas that can provide context and relate it to other information we have already learned
Ultimately, Tammet proposes that his autistic brain indeed functions like all others, but in a highly connected way. He uses the same inbuilt grammar of the mind for mathematics and language but in a highly connect way. He is not different, just enhanced in this way.