Hyperlexia was initially identified by Silberg and Silberg (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

Autism spectrum

The term "autism spectrum" is often used to describe disorders that are currently classified as pervasive developmental disorders. Pervasive developmental disorders include autism, Asperger syndrome, Childhood disintegrative disorder, Rett syndrome and Pervasive Developmental Disorder Not Otherwise...

. However, some other experts believe the involvement of autism in hyperlexia is completely dependent on the type of hyperlexia. Between 5-10% 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

Dyslexia

Dyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, orthographic coding, auditory short-term memory, or rapid...

. 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.

Developmental

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

Rote learning

Rote learning is a learning technique which focuses on memorization. The major practice involved in rote learning is learning by repetition by which students commit information to memory in a highly structured way. The idea is that one will be able to quickly recall the meaning of the material the...

 and heavy repetition, and may also have difficulty learning the rules of language from examples or from trial and error

Trial and error

Trial and error, or trial by error, is a general method of problem solving, fixing things, or for obtaining knowledge."Learning doesn't happen from failure itself but rather from analyzing the failure, making a change, and then trying again."...

, which may result in social problems. Their language may develop using echolalia

Echolalia

Echolalia is the automatic repetition of vocalizations made by another person. It is closely related to echopraxia, the automatic repetition of movements made by another person....

, 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

Language delay

Language delay is a failure to develop language abilities on the usual developmental timetable. Language delay is distinct from speech delay, in which the speech mechanism itself is the focus of delay...

. 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 behaviors which gradually fade as the child gets older.

Acquired

Although it is generally associated with autism, a 69-year old woman appears to have been made hyperlexic because of a "cerebral infarction

Cerebral infarction

A cerebral infarction is the ischemic kind of stroke due to a disturbance in the blood vessels supplying blood to the brain. It can be atherothrombotic or embolic. Stroke caused by cerebral infarction should be distinguished from two other kinds of stroke: cerebral hemorrhage and subarachnoid...

 in the left anterior cingulate cortex

Cingulate cortex

The cingulate cortex is a part of the brain situated in the medial aspect of the cortex. It includes the cortex of the cingulate gyrus, which lies immediately above the corpus callosum, and the continuation of this in the cingulate sulcus...

 and corpus callosum

Corpus callosum

The corpus callosum , also known as the colossal commissure, is a wide, flat bundle of neural fibers beneath the cortex in the eutherian brain at the longitudinal fissure. It connects the left and right cerebral hemispheres and facilitates interhemispheric communication...

".

External links

• Forum About Hyperlexia
• Readers with Autism, a website describing anaphoric cuing