Hemispheric division of labour in reading

We argue that the reading of words and text is fundamentally conditioned by the splitting of the fovea and the hemispheric division of the brain, and, furthermore, that the equitable division of labour between the hemispheres is a characteristic of normal visual word recognition. We report analyses of a representative corpus of the eye fixations of normal readers in the realistic reading of text where we compare hemispheric processing, quantified in terms of uncertainty about the orthographic, phonological and semantic representations of the words of the text. The analyses show that normal reading is accurately understood in terms of an equitable division of labour in the construction of the orthographic identity of the word and that, for English, a semantic division patterns closely with the orthographic division. We infer that impaired inter-hemispheric co-ordination of orthographic information may be best compensated for by a reliance on the inter-hemispheric co-ordination of semantic information, as in phonological dyslexia.