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Cracking the orthographic code

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A new approach to orthographic processing and reading skills

Researchers set out to design and test a new theory of orthographic processing that describes how visual features make contact with different types of letter representations that then provide access to whole-word representations and meaning. The study aimed to provide the foundations for a general account of skilled reading and its breakdown in reading-disabled persons.

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With the support of EU funding, the project O-CODE (Cracking the orthographic code) framed its theory within a general framework for word recognition that makes a critical distinction between two orthographic codes to provide a connection with auditory word processing and semantics. The first is a coarse-grained orthographic code that provides a fast-track to semantics, and the second is a fine-grained orthographic code used to generate a prelexical phonological code. One difficult issue in orthographic processing is how our brains keep track of the positions of the different letters in a word. Computational modelling provided support for a central hypothesis in the O-CODE project, that information about letter combinations is used to transform a location-specific orthographic representation into a location-invariant code. A combination of electrophysiological recordings and priming methodology offered further support for the superiority of this approach to orthographic processing. O-CODE research also helped identify the nature of processing specific to strings of letters as well as the nature of the adaptive mechanisms that are one key to the development of skilled reading behaviour. The team's investigation of orthographic processing in baboons helped link general object processing mechanisms and their adaptation to the specificities of letter string processing. The project's developmental research work further helped specify the developmental trajectories associated with the different types of orthographic code postulated in O-CODE's theoretical framework. Researchers showed that the development of flexible sublexical orthographic representations is tightly related to the development of skilled reading behaviour (as measured by standardised reading tests). Research results also point to a transition from two types of precise letter position coding during reading development: one is involved in the slow process of phonological recoding used by beginning readers, and the other is a more automatised process of grapheme-phoneme conversion used by more skilled readers. Project work also provided evidence that the well-established initial letter advantage found in skilled readers gradually emerges during primary school education. This supports the O-CODE hypothesis that this advantage is driven by adaptive mechanisms rather than serial processing.


Orthographic processing, reading, orthographic code, phonological, adaptive mechanisms

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