Word recognition in normal reading Sara C. Sereno Collaborators: RAs/PGs: Paddy O’DonnellSébastien Miellet Hartmut LeutholdGraham Scott Christopher Hand

Word Recognition What factors affect word recognition? How can word recognition processes be accurately measured? How can effects be interpreted?

Orthography of language –English vs. Hebrew or Japanese Intraword (sublexical) variables –word-initial bi/tri-gramsclown vs. dwarf –spelling-to-sound regularityhint vs. pint –neighborhood consistencymade vs. gave –morphemes prefix vs. pseudo-prefixremind vs. relish compound vs. pseudo-compoundcowboy vs. carpet What factors affect word recognition?

Word (lexical) variables –word lengthduke vs. fisherman –word frequencystudent vs. steward –AoArabbit vs. violin –expert vocabularyvoxel –syntactic classopen/closed-class; A,N,V –ambiguitybank (“money” “river”) –concreteness/imageabilitytree vs. idea –animacydog vs. cup –affective tonelove vs. farm vs. fire

What factors affect word recognition? Extraword (supralexical) variables –Contextual predictability Neutral He bought a large plant for his garden. Biasing Terry went to the new gardening centre. He bought a large plant for his garden. –Syntactic complexity Trans. Mary took the book VERBMary knew the book Intrans. Mary hoped the book on the table. was good. on the table. was good. on the table. was good.

Extraword (supralexical) variables –Discourse factors Focus The dog chased the cat today. The cat was chased by the dog today. What the dog chased was the cat today. It was the cat that was chased by the dog today. Elaborative inferences & anaphora What factors affect word recognition? weapon … The mugger her with his weapon… He threw the knife into the bushes and ran away. stabbed assaulted

What factors affect word recognition? Language skill –beginning (novice) vs. skilled (expert) readers –normal vs. dyslexic vs. neuropsychological patient How can word recognition processes be accurately measured?

Measure Task Time Res. “electrical” imaging single word presentation ~80 – 500 ms (EEG, MEG) word-by-word reading (P1,N1,EPN,N400) Eye movements in fixation time, location & ~250 ms normal reading sequence of EM’s RT naming, lexical decision ~500 – 800 ms categorization tasks; ± priming, masking, lateralized presentation “blood flow” imaging single word presentation seconds (PET, fMRI)

Thisisawordbywordpresentationofasentenceatafastreading-likerate. Word-by-word reading: 200 ms per word

Thisisawordbywordpresentationofasentenceataslowratetypically usedinERPstudies. Word-by-word reading: 600 ms per word

Normal Reading

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

This is an approximation of normal reading in real time. *

The importance of making eye movements in normal reading Cond1 There was a box of… Cond2 There was an enormous box of… Cond1 She saw a cat in the… Cond2 She saw a cup in the… Perception of text influences how EMs made. AND Location/duration of EMs affect perception.

(1) Pick factors: stimulus quality, frequency, predictability Additive factors How can effects be interpreted? Stimulus Quality Context Frequency RT Lo freq Hi freq + – stim qual RT + – context – stim + stim RT + – context Lo freq Hi freq (3) Additive sequential Interactive overlapping (2) Independently manipulate 2 factors at once:

oculomotor-related factors launch distance to word location of fixation within word number of fixations on word word length word frequency contextual predictability language-related factors How can effects be interpreted? Modelling (1) Pick factors:

oculomotor-related factors launch distance to word location of fixation within word number of fixations on word word length word frequency contextual predictability language-related factors How can effects be interpreted? Modelling (1) Pick factors: (2) Perform repeated measures multiple regression analysis to determine which factors account for most variance.

FactorsMeasuresApproach orthography bi-/tri-grams regularity neighborhood morphology length frequency jargon word class ambiguity imagability animacy emotionality predictability syntactic prefs. focus inference anaphora skill ERPs + word-by-word (slow) presentation Eye movements + normal reading EM-ERP co-registration? Additive factors Repeated measures multiple regression

Distributed hierarchical visual processing in primates lexicalhumans higher-level semantics syntax meanings word forms letters features

Conclusion Precisely delineating the time course of different components of word recognition allows us to: –determine when top-down effects modulate bottom-up processes; –inform neuroimaging localisation studies in order to construct a temporally realistic neural circuitry of normal reading.

Measurement EMs = best on-line measure of visual word recognition in the context of normal reading ERPs = best real-time measure of brain activity associated with the perceptual and cognitive processing of words

(Sereno & Rayner, Trends in Cognitive Sciences, 2003)

Sereno, Rayner, & Posner (1998). NeuroReport. Sereno, Brewer, & O’Donnell (2003). Psych. Sci.