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WORD RECOGNTION (Sereno, 2/06)
I. Introduction to psycholinguistics
II. Basic units of language
III. Word recognition
IV. Word frequency & lexical ambiguity
III. Word Recognition
How long does it take to recognise a visual word?
– What is meant by “recognition” or “lexical access”?
– Can lexical access be accurately measured?
– What factors affect lexical access and when?
The “magic moment” (Balota, 1990) of lexical access:“At this moment, presumably there is recognition that the
stimulus is a word, and access of other information (such as the meaning of the word, its syntactic class, its sound, and its spelling) would be rapid if not immediate.” (Pollatsek & Rayner, 1990)
III. Word Recognition
• Measures
• Components
• Models
• Eye movements (EMs)
• Event-related potentials (ERPs)
Measures• Standard behavioral techniques
• Eye movements (EMs)
• Neuroimaging– “Electrical”: EEG, MEG, (TMS)
– “Blood flow”: PET, fMRI
Measures• Standard behavioural techniques
– lexical decision, naming, categorisation; also RSVP, self-paced reading
– priming, masking, lateralised presentation
– Donders (1868): subtractive method• assumes strictly serial stages of processing• additive vs. interactive effects
– automatic vs. strategic (Posner & Snyder, 1975)
unconsciousexogenousbottom-upbenefit
controlledendogenoustop-downcost & benefit
RT
RT
StimulusQuality
Context
Frequency
Stim Qual X Freq
Context X Stim Qual
Context X Freq
Related cat dog 500 500
Unrelated bed dog 550 600
Neutral xxx dog 550 550
PRIME TARGET
prime target
SOA < 250 SOA > 250
RT
SOA = Stimulus Onset Asynchrony
ISI = InterStimulus Interval
time
Measures• Standard behavioral techniques
• Eye movements (EMs)
• Neuroimaging– “Electrical”: EEG, MEG, (TMS)
– “Blood flow”: PET, fMRI
MEASURE
Normal reading
TASK
fixation duration (as well aslocation and sequence of EMs)
TIME RES.
GOOD
POOR“blood flow” imaging: fMRI, PET
“electrical” imaging: EEG, MEG
various word tasks
ms-by-ms
seconds
various word tasks
naming
categorisationlexical decision
Standard word recognition paradigms (± priming, ± masking):
RT~500 ms~600 ms~800 ms
~250 ms
Components
• Orthography of language– English vs. Hebrew or Japanese
• Language skill– beginning (novice) vs. skilled (expert) reader
– easy vs. difficult text
Components
• Intraword variables– word-initial bi/tri-grams clown vs. dwarf
– spelling-to-sound regularity hint vs. pint
– neighborhood consistency made vs. gave
– morphemes• prefix vs. pseudoprefix remind vs. relish• compound vs. pseudocompound cowboy vs. carpet
Components
• Word variables– word length duke vs. fisherman
– word frequency student vs. steward
– AoA dinosaur vs. university
– ambiguity bank vs. edge, brim
– syntactic class open vs. closed; A,N,V
– concreteness tree vs. idea
– affective tone love vs. farm vs. fire
– etc.
Components
• Extraword variables– contextual predictability
The person saw the... moustache.The barber trimmed the...
– syntactic complexity Mary took the book. *Mary took the book was good. Mary knew the book. Mary knew the book was good.*Mary hoped the book. Mary hoped the book was good.
– discourse factors (anaphora, elaborative inferences)He assaulted her with his weapon.... ...knife... stabbed
Models• Dual-route account (Coltheart, 1978)
Direct route(addressed)
phonology
semantics
orthography
Indirect route(assembled)
Models• Dual-route account (Coltheart, 1978)
Direct route(addressed)
phonology
semantics
orthography
Indirect route(assembled)
Deep dyslexia- visual/semantic errors (sympathy -> orchestra)- can’t read nonwords
Models• Dual-route account (Coltheart, 1978)
Direct route(addressed)
phonology
semantics
orthography
Indirect route(assembled)
Surface dyslexia- regularization errors (broad -> brode)- Reg wds,NWs are OK (GPC rules intact)
Models• Interactive (Morton, 1969; Seidenberg & McClelland, 1989)
/m A k/
phonology
meaning
orthography
M A K E
context
Models• Modular (Forster, 1979; Fodor, 1983)
decision output
Lexicalprocessor
Syntacticprocessor
Messageprocessor
GeneralProblemSolver
input features
Models• Hybrid
– 2-stage: generate candidate set selection
– (Becker & Killion; Norris; Potter)
III. Word Recognition
• Measures
• Components
• Models
• Eye movements (EMs)
• Event-related potentials (ERPs)
MEASURE
Normal reading
TASK
fixation duration (as well aslocation and sequence of EMs)
TIME RES.
GOOD
POOR“blood flow” imaging: fMRI, PET
“electrical” imaging: EEG, MEG
various word tasks
ms-by-ms
seconds
various word tasks
naming
categorisationlexical decision
Standard word recognition paradigms (± priming, ± masking):
RT~500 ms~600 ms~800 ms
~250 ms
Tools of choice:• Recording eye movements in reading
• Recording ERPs in language tasks
Eye Movements (EMs)
Best on-line measure of visual word recognition in the context of normal reading:
• Fast (avg fixation time ≈ 250 ms)
• Ecologically valid task
• Eye-mind span is tight
fixation onset
visual cortex
0 50 100 150 200 250 300 350 400
LEXICAL ACCESS
fixation onset
initiate saccade
modify EM program
shift attention, initiate EM
motor program
signal to eye
muscles
EYE MOVEMENTS
ERPs
Best real-time measure of brain activity associated with the perceptual and cognitive processing of words:
• Continuous ms-by-ms record of events• Early, exogenous components (before 200 ms) should
reflect lexical processing
P1
N1
P300
N400
Numberof trials
1
2
4
8
16
EEG
ERP
(Sereno & Rayner, Trends in Cognitive Sciences, 2003)
DIVERSION
High-density ERP Analysis:A case of “too many notes”?
High-density ERP Analysis:Typical approaches for space & time
• Pick ‘n choose favourite electrode and ERP component
High-density ERP Analysis:Typical approaches for space & time
• Pick ‘n choose favourite electrode and ERP component
• Hunt down where/when the effect is strongest and gather data from those electrodes/time window
High-density ERP Analysis:Typical approaches for space & time
• Pick ‘n choose favourite electrode and ERP component
• Hunt down where/when the effect is strongest and gather data from those electrodes/time window
• Procrustean regions analysis (turtle shell) or series of pre-set time windows (eg, 50, 100, 200 ms)
Single channel ERP
-5
-4
-3
-2
-1
0
1
2
3
0 50 100 150 200 250 300 350 400
Time (ms)
Voltage(µV)
Series1
High-density ERP Analysis:Typical approaches for space & time
• Pick ‘n choose favourite electrode and ERP component
• Hunt down where/when the effect is strongest and gather data from those electrodes/time window
• Procrustean regions analysis (turtle shell) or series of pre-set time windows (eg, 50, 100, 200 ms)
• Spatial and/or temporal principal component analysis (PCA)
Scalp topography of the N1 @ 132-192 ms
SF1 loadings Voltages
(Sereno, Brewer, & O’Donnell, Psychological Science, 2003)
Scalp topography of the N1 @ 132-192 ms
SF1 loadings Voltages
± 0.7 factor loading contours
WORD RECOGNTION (Sereno, 1/05)
I. Introduction to psycholinguistics
II. Basic units of language
III. Word recognition
IV. Word frequency & lexical ambiguity
Frequency: “When is access?”
• A word frequency effect [ HF < LF ] is used as a marker (index) of successful word recognition (lexical access).
The sore on Tam-Tam’s was swollen.(HF) back(LF) rump
• Word frequency effect = differential response to commonly used high-frequency (HF) words vs. low-frequency (LF) words that occur much less often:
• If you can track frequency, you can track lexical access...
553 ms490 ms
259 ms275 ms
280 ms293 ms
(Sereno & Rayner, Trends in Cognitive Sciences, 2003)
(Sereno & Rayner, Trends in Cognitive Sciences, 2003)