Simran Shet Parkar, M. Optom

Lecturer of Optometry, Acharya Institute of Allied Health Sciences (AIAHS), Karnataka, India


Do you know what is computing in your brain when you are reading? Well from the perspective of neuroscience, reading requires multiple processing at the level of the brain. It is a complex process that acquires meaning from written or printed words by decoding and linguistic comprehension. (1) To date, many theories regarding reading have been proposed and improvised (2) amongst which the dual cascade route (DRC) model is the most successful. (3)

The DRC Model

According to this model, reading requires two systems (Figure 2): Lexical and non-lexical paths. This is based on the theory that novel words are processed differently than known words.


Lexical Path

On average 3rd to 12th grade children acquire approximately 3000 new words which get stored in the mind.(4) Accordingly, whenever a person reads known words, he/she tends to access the lexicon dictionary for pronunciation and meaning. The semantic system in the lexical path deals with the meaning of the word read. Whereas the orthographic to phonological conversion deals with the pronunciation of known words. Where orthographic inputs stand for the conventional spelling of the language and phonology is the sound or pronunciation of the word.

Non-lexical Path

When you come across a new word, it is processed through the non-lexical or grapheme-phoneme system. A grapheme to phoneme implies letter-to-sound conversion. For example, the graphemes ‘C’ ‘K’ ‘CK’ ‘QU’ stands for the phoneme /k/ and vice versa. The non-words and regular words are read through this route.

Figure 3 gives an overview of the processing of the DRC model for the word “BOOK”.

Reading Disorders

Reading disorders termed “Dyslexia” are evident for such pathways of reading (1,5). Conferring dyslexia, surface dyslexia exhibits semantic involvement while non-lexical involvement displays phonological dyslexia. On the other hand, deep dyslexia resembles phonological impairment with semantic errors. (1)


The knowledge of the neurological pathways of reading will improve the diagnosis and better management of reading disorders.



  1. Hoover, W. A., & Gough, P. B. (1990). The simple view of reading. Reading and writing2, 127-160.
  2. Ramoo, D. Psychology of Language Psychology of Language.
  3. Coltheart, M., Rastle, K., Perry, C., Langdon, R., & Ziegler, J. (2001). DRC: a dual route cascaded model of visual word recognition and reading aloud. Psychological review108(1), 204.
  4. Anderson, R. C., & Pearson, P. D. (1984). A schema-theoretic view of basic processes in reading comprehension. Handbook of reading research1, 255-291.
  5. Wajuihian, S. O., & Naidoo, K. S. (2011). Dyslexia: an overview. African Vision and Eye Health70(2), 89-98.

 Image courtesy: The images used in the picture is created by author