 The dual @-@ route theory of reading aloud was first described in the early 1970s . This theory suggests that two separate mental mechanisms , or cognitive routes , are involved in reading aloud . One mechanism is the lexical route , which is the process whereby skilled readers can recognize known words by sight alone , through a " dictionary " lookup procedure . The other mechanism is the nonlexical or sublexical route , which is the process whereby the reader can " sound out " a written word . This is done by identifying the word 's constituent parts ( letters , phonemes , graphemes ) and applying knowledge of how these parts are associated with each other , for example , how a string of neighboring letters sound together . The dual @-@ route system could explain the different rates of dyslexia occurrence between different languages ( e.g. the Spanish language dependence on phonological rules accounts for the fact that Spanish @-@ speaking children show a higher level of performance in non @-@ word reading , when compared to English @-@ speakers ) . 
