Saturday 15 August 2009

The “Dual Route” Theory for Reading

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The “Dual Route” Theory for Reading

The most comprehensive and well-supported model of reading to date is the “Dual Route” theory (Jobard, Crivello and Tzourio-Mazoyer, 2003). This theory provides a framework for describing reading in the brain at the level of the word.

As you look at the words on this page, this stimulus is first processed by the primary visual cortex. Then, pre-lexical processing occurs at the left occipito-temporal junction.

The dual route theory posits that processing then follows one of two complementary pathways. The assembled pathway involves an intermediate step of grapho-phonological conversion – converting letters/words into sounds – which occurs in certain left temporal and frontal areas, including Broca’s area.

The addressed pathway consists of a direct transfer of information from pre-lexical processing to meaning (semantic access). Both pathways terminate in the left basal temporal area, the left interior frontal gyrus, and the left posterior middle gyrus, or Wernicke’s area.

The pathway involving direct access to meaning has led to the proposal of a “visual word form area” (VWFA) at the ventral junction between the occipital and temporal lobes. This area was first proposed to contain a visual lexicon or collection of words which functions to immediately identify whole words when they are seen.

Recent research has suggested a modified conclusion that this region may actually consist of constellations of adjacent areas sensitive to various aspects of letter strings, such as length or order of words. The entire process from visual processing (seeing) to semantic retrieval (understanding) occurs very rapidly, all within about 600 mili-seconds.

"Understanding the Brain", The Birth of a Learning Science, 2007, page 87

Saturday 1 August 2009

Literacy Being Built “on Top of” Language

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Literacy Being Built “on Top of” Language

While the brain is not necessarily biologically inclined to acquire literacy, it is biologically inclined to adapt to experience. It is, for instance, endowed with language circuitry capable of processing visual input.

The brain’s plastic capacities of adaptability enable the stimuli coming from experience to utilise language structures when constructing the neural circuitry capable of supporting literacy. This is often expressed as literacy being built “on top of” language. In the terms of Vygotsky’s classic metaphor, language structures provide scaffolding for literacy to be constructed in the brain (Vygotsky, 1978).

Since literacy is built, in part, with language circuitry, future research should investigate the possibility that developmental sensitivities for certain aspects of language acquisition influence the facility with which the different aspects of reading are acquired.

If such influences were identified, this would have implications for educational policy and practice regarding the timeframe for teaching different literacy skills, and could well reinforce the importance of developing pre-literacy skills in early
childhood.

Research aimed at delineating the cortical areas supporting reading is rapidly accumulating. The most comprehensive and well-supported model of reading to date is the “dual route” theory (Jobard, Crivello and Tzourio-Mazoyer, 2003).

"Understanding the Brain", The Birth of a Learning Science, 2007, page 87