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. w/o/l/f PHONOLOGICAL SYSTEM WOLF WOLF “WOLF” VISUAL VISUAL SEMANTIC SPEECH PROCESSES WORD-FORM SYSTEM SYSTEM 10 consonants & 2 consonants & 11 consonants 5 vowels GRAPHEME UNITS INTERMEDIATE UNITS SEMEMEvowels UNITS CLEANUPvowels UNITS BED The network’s weights are adjusted by WWW a numerical process (“back-propogation”). NEURON WW W W Copyright 1993 Scientific American, Inc. Copyright 1993 Scientific American, Inc. 10 consonants & 2 consonants & 11 consonants 5 vowels GRAPHEME UNITS INTERMEDIATE UNITS SEMEMEvowels UNITS CLEANUPvowels UNITS BED This version of the model was not very satisfactory. Without a huge amount of training, it has a strong tendency to map similar inputs (CAT, COT) to similar semantic outputs.
Copyright 1993 Scientific American, Inc.
CLEANUP UNITS
The
SEMEME UNITS new network is dynamic: it settles
Feedback INTERMEDIATE gradually into a UNITS connections stable pattern.
GRAPHEME UNITS Feedforward connections
Copyright 1993 Scientific American, Inc. Begin Initial semantic representation Final semantic End representation GRAPHEME UNITS INTERMEDIATE UNITS SEMEME UNITS CLEANUP UNITS
Copyright 1993 Scientific American, Inc. GRAPHEME UNITS INTERMEDIATE UNITS SEMEME UNITS CLEANUP UNITS
GRAPHEME UNITS INTERMEDIATE UNITS SEMEME UNITS CLEANUP UNITS Copyright 1993 Scientific American, Inc.
Copyright 1993 Scientific American, Inc. GRAPHEME UNITS INTERMEDIATE UNITS SEMEME UNITS CLEANUP UNITS
CLEANUP UNITS
SEMEME UNITS
INTERMEDIATE UNITS GRAPHEME UNITS Copyright 1993 Scientific American, Inc.
Copyright 1993 Scientific American, Inc. Semantic Space
Bed
Cot
Normal Semantic Space
Bed
* Cot
Damaged “BED” “COT” “CAT”
BED
b a COT c COT (DAMAGED) CAT SEMANTIC SPACE
Copyright 1993 Scientific American, Inc. GRAPHEME UNITS INTERMEDIATE UNITS SEMEME UNITS CLEANUP UNITS
Copyright 1993 Scientific American, Inc. GRAPHEME UNITS INTERMEDIATE UNITS SEMEME UNITS CLEANUP UNITS
Copyright 1993 Scientific American, Inc. GRAPHEME UNITS INTERMEDIATE UNITS SEMEME UNITS CLEANUP UNITS Copyright 1993 Scientific American, Inc. “BED” “COT” “CAT”
BED
b a COT c COT (DAMAGED) CAT SEMANTIC SPACE
Copyright 1993 Scientific American, Inc. “BED” “COT” “CAT” “BED” “COT” “CAT” BED b a BED COT c COT (DAMAGED) b a CAT COT c COT (DAMAGED) SEMANTIC SPACE CAT SEMANTIC SPACE Copyright 1993 Scientific American, Inc.
Copyright 1993 Scientific American, Inc. “BED” “COT” “CAT”
BED
b a COT c COT (DAMAGED) CAT SEMANTIC SPACE
Copyright 1993 Scientific American, Inc. Essential ingredients: Cleanup units downstream of the damage.
CLEANUP UNITS
SEMEME UNITS
INTERMEDIATE UNITS
GRAPHEME UNITS
Copyright 1993 Scientific American, Inc. Abstract words are read more poorly than concrete words in deep dyslexia.
SPEECH SYNTHESIZER CLEANUP UNITS PHONEME UNITS k/a/t INTERMEDIATE UNITS CLEANUP UNITS SEMEME UNITS INTERMEDIATE UNITS GRAPHEME UNITS "CAT"
Copyright 1993 Scientific American, Inc. “BED” “COT” “CAT”
BED
b a COT c COT (DAMAGED) CAT SEMANTIC SPACE
Copyright 1993 Scientific American, Inc.