Understanding hyperlexia may also help explain how normal brains accomplish the feat of reading. Unlike seeing and hearing, skills acquired through evolution, reading is usually not acquired naturally. Humans have been reading for only a few thousand years, and the pressure for everyone to become good readers has become intense in only the past couple of centuries.
Reading involves a complex series of brain activities: Visual centers must first perceive variable, tiny features of printed symbols on a page, then those changes must be mentally converted into strings of sound, and finally the patterns of sound must be interpreted by language centers in the brain to register their meaning.
'Hyperlexia is the antithesis of dyslexia,' said Guinevere Eden, director of Georgetown University's Center for the Study of Learning, who has studied Alex. 'We spend all our time studying individuals who have a hard time learning to read, and here are these children who acquire reading in a spontaneous way. It's as if they know it already.'
Twenty years ago, when I first did a neuropsych course, I thought the "miracle of reading" was the most interesting question in human evolution. I guessed, as have many, that it developed from sign language. Indeed, if sign language preceded fluent verbalization, it may be that reading is more fundamental than speaking.
That would fit this story -- hyperlexic children often have difficulty with speech. We know from brain injured patients that speaking and reading abilities are likewise somewhat independent.
It would be very interesting to know how quickly hyperlexic children learn to sign, and whether there's a relationship in deaf children between signing ability and reading ability.