Children with hyperlexia demonstrate an intense fascination with letters, numbers, patterns and logos, and a self-taught, precocious ability to read, spell, write and/or compute, usually before the age of five. They have difficulty developing language and communication skills and often exhibit unusual interests or behaviours, notably difficulty in reciprocal interaction with others. Hyperlexia has characteristics similar to autism, behavior disorder, language disorder, emotional disorder, attention deficit disorder, hearing impairment, giftedness or, paradoxically, mental retardation.