Abstract: Cognitive neuropsychology explained the mechanism of acquired dyslexia as selective impairment for task specific procedures, such as grapheme-phoneme translation route for non-word reading. Recently, in the framework of connectionist triangle model of reading, “Primary System” hypothesis explained the acquired dyslexia as the impairment in different primary system (e.g., visual, phonology and semantics). Both the reading and non-reading task was influenced by the deficit in these primary systems. This approach suggested a new mechanism of all kinds of acquired dyslexia, as well as the relationship between dyslexia and other cognitive functional deficits. This paper elaborated it in the detail

Key words: connectionist, primary system, surface dyslexia, phonological dyslexia, deep dyslexia