Hyperlexia was initially identified by Silberberg and Silberberg (1967), who defined it as the precocious ability to read words without prior training in learning to read typically before the age of 5. They indicated that children with hyperlexia have a significantly higher word decoding ability than their reading comprehension levels.
Hyperlexic children are characterized by having average or above average IQs and word-reading ability well above what would be expected given their age. First named and scientifically described in 1967, it can be viewed as a superability in which word recognition ability goes far above expected levels of skill. Some hyperlexics, however, have trouble understanding speech. Some experts believe that most or perhaps all children with hyperlexia lie on the autism spectrum. However, some other experts believe the involvement of autism in hyperlexia is completely dependent on the type of hyperlexia. Between 5 and 10 percent of children with autism have been estimated to be hyperlexic.
Hyperlexic children are often fascinated by letters or numbers. They are extremely good at decoding language and thus often become very early readers. Some hyperlexic children learn to spell long words (such as elephant) before they are two years old and learn to read whole sentences before they turn three. An fMRI study of a single child showed that hyperlexia may be the neurological opposite of dyslexia. Whereas dyslexic children usually have poor word decoding abilities but average or above average reading comprehension skills, hyperlexic children excel at word decoding but often have poor reading comprehension abilities.
Despite hyperlexic children's precocious reading ability, they may struggle to communicate. Often, hyperlexic children will have a precocious ability to read but will learn to speak only by rote and heavy repetition, and may also have difficulty learning the rules of language from examples or from trial and error, which may result in social problems. Their language may develop using echolalia, often repeating words and sentences. Often, the child has a large vocabulary and can identify many objects and pictures, but cannot put their language skills to good use. Spontaneous language is lacking and their pragmatic speech is delayed. Hyperlexic children often struggle with Who? What? Where? Why? and How? questions. Between the ages of 4 and 5 years old, many children make great strides in communicating.
The social skills of a child with hyperlexia often lag tremendously. Hyperlexic children often have far less interest in playing with other children than do their peers.
Types of hyperlexia 
Some experts denote three explicit types of hyperlexics. Specifically:
- Type 1: Neurotypical children that are very early readers.
- Type 2: Children on the autism spectrum that demonstrate very early reading as a splinter skill.
- Type 3: Very early readers who are not on the autism spectrum though there are some “autistic-like” traits and behaviours which gradually fade as the child gets older.
Although it is generally associated with autism, a 69-year old woman appears to have been made hyperlexic because of a "cerebral infarction in the left anterior cingulate cortex and corpus callosum".
Further reading 
- Gilman, Priscilla (2012),The Anti-Romantic Child: A Memoir of Unexpected Joy
- Jensen, Audra (2005), When Babies Read: A Practical Guide to Helping Young Children with Hyperlexia, Asperger Syndrome and High-Functioning Autism
- Miller, Susan Martins (1993), Reading Too Soon: How to Understand and Help the Hyperlexic Child
- Silberberg, N.E., & Silberberg, M.C. (1968–69), "Case histories in hyperlexia," Journal of School Psychology, 7, 3–7.
- Silberberg, N.E., & Silberberg, M.C. (1967), "Hyperlexia: Speciﬁc word recognition skills in young children," Exceptional Child, 34, 41–42.
- Richman, Lynn, C.; Wood, K.M. (2002). "Learning disability subtypes: classification of high functioning hyperlexia". Brain and Language 82 (1): 10–21. doi:10.1016/S0093-934X(02)00007-X. PMID 12174811.
- Tina M. Newman Æ Donna Macomber Adam J. Naples Æ Tammy Babitz Æ Fred Volkmar Æ Elena L. Grigorenko. (2007). Hyperlexia in Children with Autism Spectrum Disorders. 37:760-774-2. J Autism Dev Disord
- "Hyperlexia--specific word recognition skills in young children". Exceptional Children 34 (1): 41–2. 1967. PMID 6066378.
- Grigorenko EL, Klin A, Volkmar F (2003). "Annotation: Hyperlexia: disability or superability?". J Child Psychol Psychiatry 44 (8): 1079–91. doi:10.1111/1469-7610.00193. PMID 14626452.
- Treffert, MD, Darold A (2011). "Hyperlexia: Reading Precociousness or Savant Skill? Distinguishing autistic-like behaviors from Autistic Disorder". Retrieved 2013-01-22. (WebCite archive of 2013-01-22).
- Burd, L., & Kerbeshian, J. (1985). Hyperlexia and a variant of hypergraphia. 60:940-942. Perceptual and Motor Skills,
- Turkeltaub PE, Flowers DL, Verbalis A, Miranda M, Gareau L, Eden GF (2004). "The neural basis of hyperlexic reading: an FMRI case study". Neuron 41 (1): 11–25. doi:10.1016/S0896-6273(03)00803-1. PMID 14715131.
- Suzuki T, Itoh S, Hayashi M, Kouno M, Takeda K. . Hyperlexia and ambient echolalia in a case of cerebral infarction of the left anterior cingulate cortex and corpus callosum. Neurocase. 6:1-6. doi:10.1080/13554790902842037 PMID 19585352