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Language ComprehensionreadingResearch MethodsEye movement analysesEye fixation durations during normal readingMoving window techniqueMoving window techniqueReading From orthography to meaningReading PathwaysPhonological mediation occurs in readingBut... phonological mediation not necessaryDeep Dyslexia: example patientModeling Deep DyslexiaNeural Network Model for Deep DyslexiaWhat the network learnsSimulating Brain DamageReading aloudfrom orthography to phonologyDual Route Models of ReadingSurface DyslexiaExplaining Surface DyslexiaPhonological DyslexiaExplaining phonological dyslexiaNeural Network ApproachA Neural Network ModelPlaut et al. (1996) SimulationsPlaut et al. (1996) SimulationsDemoLanguage ComprehensionreadingResearch Methods• Recording eye movements during reading• Computational modeling• NeuropsychologyEye movement analyses• Saccadic movement: rapid movement of the eyes from one spot to another spot as one reads•Fixation: these occur between saccadic movements. Information is obtained at fixationEye fixation durations during normal reading201 188 203 220 217 288 212 75260271188350215221 266 277 120 219312a regressionand creativity has provided some surprisingly good news. Regularbouts of aerobic exercise may also help spark a brainstorm of creativRayner & Pollatsek (1988)Normal readerSpeed readerSkimmerMoving window techniqueTHE HANDSOME FROG KISSED THE PRINCESS AND TURNED …XHZ KLNDSOME FROG KISSED THE PRINCAWS NBD YRWVAA …GJUI DHABOPLH DROG KISSED THE PRINCESS ANQ DWEVDTA …• Random letters presented outside window; windowmoves with eyes• When window is large enough should have no effect (Rayner, 1975, 1981, 1986)Moving window technique• Perceptual span to identify words:– ~3 letters to left of fixation– ~8 letters to right of fixation– Span is asymmetric to right • Span reverses for people who read from right-left (e.g. Hebrew) and is asymmetric to left (Rayner, 1975, 1981, 1986)Reading From orthography to meaningContextGrammarpragmaticsSemanticsmeaningOrthographytextPhonologyspeechConnectionist framework for lexical processing, adapted from Seidenberg and McClelland (1989) and Plaut et al (1996).ContextGrammarpragmaticsSemanticsmeaningOrthographytextPhonologyspeechDirect accessPhonologically mediated routeConnectionist framework for lexical processing, adapted from Seidenberg and McClelland (1989) and Plaut et al (1996).Reading PathwaysThere are two possible routes from the printed word to its meaning:(1) Spelling→meaning, the route from the spelling of the printed word to meaning at the top(2) Spelling→phonology→meaning: the print is first related to the phonological representation and then the phonological code is linked to meaning, just as in speech perception.Æ Both routes may be used in various degreesPhonological mediation occurs in reading• Evidence for usage of route– Semantic decisions on homophones e.g. Van Orden (1987)• icecream a food?• meet a food? -> slow “no” response• rows a flower? -> slow “no” responseBut... phonological mediation not necessary• Some brain-damaged patients can understand (some) written words without any apparent access to their sound pattern• Phonological dyslexics can still read (Levine et al, 1982)– Patient EB– Reading comprehension slow but accurateUnable to choose which 2 of 4 written words sounded the same, or rhymed• The relative contribution of the two routes to meaning-activation depends on word frequency (e.g. Jared & Seidenberg, 1991, JEP:Gen)Deep Dyslexia: example patientSemantic Errorscanoe Æ kayakonion Æ orangewindow Æ shadepaper Æ pencilnail Æ fingernailache Æ Alka SeltzerVisual Errorscat Æ cotfear Æ flagrage Æ raceModeling Deep DyslexiaMapping between these networks might be disruptedSemanticsmeaningOrthographytextPhonologyspeechPlaut and Shallice (1993); Hinton, Plaut and Shallice (1993)Neural Network Model for Deep Dyslexia• Network learns mapping between letter features and meaning features• Hidden units provide a (non-linear) mapping between letter codes and meaning features• Feedback connections: part of a feedback loop that adjusts the meaning output to stored patterns• Learning was done with back-propagation Letter featuresHidden unitsMeaning featuresPlaut and Shallice (1993); Hinton, Plaut and Shallice (1993)What the network learns• The network created semantic attractors: each word meaning is a point in semantic space and has its own basin of attraction.For a demonstration of attractor networks with visual patterns: http://www.cbu.edu/~pong/ai/hopfield/hopfieldapplet.htmlsemantic spacevisual spacecot catSimulating Brain Damage• Damage to the semantic units can change the boundaries of the attractors. This explains both semantic as well as visual errors -- meanings fall into a neighboring attractor.new semantic space“cot”“cat”old semantic space“cot”“cat”Visual error: Cat might be called “cot”Semantic error: Bed might be called “cot”Reading aloudfrom orthography to phonologyContextGrammarpragmaticsSemanticsmeaningOrthographytextPhonologyspeechReading out loudDual Route Models of ReadingOrthographyLexicalRouteSpelling lookupLexiconGrapheme-phonemeconversion rulesPhonologySublexicalroutenecessary for exception words, e.g. PINT, COLONELnecessary for regular and unfamiliar words, e.g. VINT(e.g., Colheart, Curtis, Atkins, & Haller, 1993)Surface Dyslexia• Difficulty reading irregular words. – tendency to regularize irregular words (e.g. broad--> “brode”)– Patients read GLOVE as rhyming with COVE and FLOOD with MOOD• Damage to lexical route?Explaining Surface DyslexiaOrthographyLexicalRouteSpelling lookupLexiconGrapheme-phonemeconversion rulesPhonologySublexicalroutenecessary for exception words, e.g. PINT, COLONEL(e.g., Colheart, Curtis, Atkins, & Haller, 1993)Phonological Dyslexia• Difficulty reading nonwords• Correctly read – irregular words (e.g. YACHT)– regular words (e.g. CUP)• Damage to sublexical route?• Video demonstration– http://psych.rice.edu/mmtbn/– Language->introduction->reading aloud words/nonwordsExplaining phonological dyslexiaOrthographyLexicalRouteSpelling lookup(e.g., Colheart, Curtis, Atkins, & Haller, 1993)LexiconGrapheme-phonemeconversion rulesSublexicalroutePhonologyNeural Network Approach• E.g., Seidenberg and McClelland (1989) and Plaut(1996).• Central to these models is the absence of any lexicon. No multiple routes from orthography to


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UCI P 140C - Language Comprehension

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