PICTURE NAMING DEFICITS IN DEVELOPMENTAL DYSLEXIA - THE PHONOLOGICAL REPRESENTATIONS HYPOTHESIS

The picture and word naming performance of developmental dyslexics was compared to the picture and word naming performance of non-dyslexic ( ''garden variety'') poor readers, reading age, and chronological age-m atched controls. The stimulus list used for both tasks was systematica lly manipulated for word length and word frequency. In order to examin e picture naming errors in more depth, an object name recognition test assessed each subject's vocabulary knowledge of those names which the y were unable to spontaneously label in the picture naming task. Findi ngs indicated that the dyslexic and the garden variety poor readers ex hibited a picture naming deficit relative to both chronological and re ading age-matched controls. Findings also indicated that both groups o f impaired readers obtained superior scores in the word naming task th an in the picture naming task, while both groups of controls showed no difference in performance across tasks. The dyslexics' picture naming errors, but not those of the garden variety poor readers, were partic ularly marked on polysyllabic and/or low frequency words, indicating a possible phonological basis to the picture naming deficit of the dysl exic children. These children also recognized significantly more unnam ed target words than all comparison groups, suggesting a particular di fficulty in retrieving the phonological codes of known picture names r ather than a vocabulary deficit. Results are discussed in terms of dys lexics' difficulty in encoding full segmental phonological representat ions of names in long-term memory and/or in professing these represent ations in order to generate required names on demand. (C) 1997 Academi c Press.