Deficient anchoring – a potential link between perceptual and cognitive difficulties among learning impaired individuals

Dyslexia – a substantial difficulty in acquiring fluent and efficient reading – is the most common form of learning disability, present in more than 80% of the individuals diagnosed with learning problems (Snow, Burns, & Griffin, 1998). While early academic research described dyslexia as a visual disorder, "congenital word blindness" (e.g., Morgan, 1896; Orton, 1928), studies in the last 40 years revealed that a major obstacle in learning to read involves the auditory system and particularly the phonological system. Phonological processing relates to processing of speech sounds, including the smallest components, phonemes. Individuals with dyslexia have difficulties mapping (or consistently matching) between letters (the basic visual elements in reading) and the phonemes they represent (see Shaywitz, Morris, & Shaywitz, 2008; Vellutino, Fletcher, Snowling, & Scanlon, 2004 for recent reviews). Dyslexic individuals also have difficulties in verbal working memory (e.g. their verbal span in terms of the number of digits they can accurately repeat is smaller than expected from their age, education and non-verbal intelligence) and in rapid naming of letters, digits and other symbols. The attempt to describe these characteristics as reflecting a single core deficit led to the "phonological deficit hypothesis", which suggests that dyslexics' core deficit resides in their poor representations of speech constituents, i.e. phonological representations (Snowling, 2000).