Page "Reading for special needs" Paragraph 7

The dual-route approach suggests that two separate mechanisms, or routes, can be used in word reading.

Words that follow spelling-sound rules ( including regular words and nonwords that follow letter-to-sound rules ) are processed through the nonlexical route.

The nonlexical route follows a system of rules specifying the relationship between letters and sounds to process words.

Conversely, exception words, or irregular words, that do not follow the spelling-sound rules are processed through the lexical route.

The lexical route can be thought of as a dictionary lookup procedure.