A computational model of the mapping between a visual word and meaning w/o/l/f PHONOLOGICAL SYSTEM WOLF WOLF “WOLF” VISUAL VISUAL SEMANTIC SPEECH PROCESSES WORD-FORM SYSTEM SYSTEM WWW NEURON WW W W Copyright 1993 Scientific American, Inc. Deep Dyslexia Semantic errors, such as "tartan" read as "kilt" or"anchor" read as "boat". Visual errors: a visual error in reading is when the response shares many letters with the stimulus, such as quarrel read as "squirrel" or angel read as "angle". Morphological errors: a morphological error in reading is when a prefixed or suffixed word is read with the root of the word correct but the prefix or suffix wrong, such as running read as"runner" or unreal read as "real". Concreteness effect: concrete (highly-imageable) words such as tulip or green are much more likely to be successfully read than abstract (difficult- to-image) words such as idea or usual. Function words such as and, the or or are very poorly read. Nonwords such as vib or ap cannot be read aloud at all. Spelling/writing may be impossible; if it is at all possible, then it usually shows the spelling equivalent of the above 6 symptoms. w/o/l/f PHONOLOGICAL SYSTEM WOLF WOLF “WOLF” VISUAL VISUAL SEMANTIC SPEECH PROCESSES WORD-FORM SYSTEM SYSTEM In deep dyslexia, the phonological route is completely abolished by damage and the semantic route is partially impaired. But why, do we see this specific pattern of impairment? In particular, why do patients make both semantic errors and visual errors? WWW NEURON WW W W Copyright 1993 Scientific American, Inc. Deep dyslexia is a “symptom-complex”. Semantic errors, such as "tartan" read as "kilt" or"anchor" read as “boat". Visual errors: a visual error in reading is when the response shares many letters with the stimulus, such as quarrel read as "squirrel" or angel read as "angle". PRINT Letter Identification Semantic System Orthographic Lexicon Grapheme- phoneme conversion rules Phonological Lexicon Box and arrow diagram Which is the ? SPEECH OUTPUT Nonlexicalof single word reading route Note: this diagram cannot explain why visual errors always co-occur with semantic errors. w/o/l/f PHONOLOGICAL SYSTEM WOLF WOLF “WOLF” VISUAL VISUAL SEMANTIC SPEECH PROCESSES WORD-FORM SYSTEM SYSTEM WWW NEURON WW W W Copyright 1993 Scientific American, Inc. w/o/l/f PHONOLOGICAL SYSTEM WOLF WOLF “WOLF” VISUAL VISUAL SEMANTIC SPEECH PROCESSES WORD-FORM SYSTEM SYSTEM Grapheme Units Intermediate Units WWW Sememe Units NEURON WW W W Copyright 1993 Scientific American, Inc.