PS: Introduction to Psycholinguistics

PS: Introduction to Psycholinguistics

Winter Term 2005/06

Instructor: Daniel Wiechmann

Office hours: Mon 2-3 pm

Email: [email protected]

Phone: 03641-944534

Web: www.daniel-wiechmann.net

Session 3:Visual processing

Sensory input

Perceptual organization

Object Recognition

Buttom-up processing - Visual processing originates from sensory input

Experience

Session 3:Visual processing

Sensory input

Perceptual organization

Object Recognition

Prior Experience

Top-down processing

Session 3:(visual) word recognition

Word level

Letter level

Feature level

CAT

Assumption: word recognition sequential buttom-up-process


Word level

Letter level

Feature level

Stimulus: COAT

top-down effects(word superiority effect)

buttom-up effects


Summary

- word recognition is a combination of buttom-up sensory information and top-down knowledge

- word recognition is bi-directional (not sequential) and graded (not discrete)

- interactive activation model violates the sequential and discreteness assumptions of a strict information processing model

Session 3:(visual) word recognition/ methods

Methods to explore visual recognition Brain imaging Examining eye movements Word identification tasks Categorisation times Tachistoscopic identification


word identification techniques Naming task

Subjects name visually presented a wordsNaming latency is measured (RT ~ 500ms from onset

of stimulus) Lexical decision task

Subjects decide whether string/sequence is a word or not

RT and error rate is measured


Eye movement in reading e.g. Limbus tracking

Infra red beam is bounced off the eyeball and tracks the the boundary between the iris and the white of the eye (limbus)

Session 3:(visual) word recognition/observations

Reading involves rapid ‘jumps’ called saccades (25 - 60 ms in duration); length is about eight letters 10% of all saccades move backwards

Average fixation times range between 200-250 ms Information retrieval takes place in that interval Average span: 15 to the right, 3-4 left (for left to right

processing)

Session 3:Towards a model of reading

a simple model model Readers fixate on a word until they have

processed it sufficiently Then eyes move to the next word


But... Only 80% content words are fixated Only 20% of function words are fixated Rare words are fixated longer than common words Words that are more predictable in sentence context are

fixated for less time Words that are not fixated tend to be common, short, or

predictable Fixation time of a word is longer when it is preceded by

a rare word (spillover effect)


Problems for the simple model: It is hard to see how readers could skip words It takes about 150-200ms to execute an eye-

movement program -> readers would waste time waiting for their eyes to move


Advantages eye-movement recording: It provides a detailed on-line record of attention-

relation processes Unobstrusive

Disadvantage Hard to to be sure exactly what processing

occurs during each fixation


E-Z reader model (Reichle 1998) Readers check frequency (F) of fixated word Completion of F-check is the signal to initiate

eye-movement program


E-Z reader model (Reichle 1998) Readers also engage in lexical access (identify

orthographic and/or phonological pattern so that semantic information can be retrieved)

Completion of lexical access is signal for shift of attention to the next word


E-Z reader model (Reichle 1998) cont.: F-check and lexical access are faster for common

words (due to organization of mental lexicon) F-check and lexical access are completed faster

for predictable words

Session 3:Towards a model of reading: E-Z reader model

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1 2 3 4 5 6 7 8 9 10 11

eye-movementexecutedcompletion offrequency checkcompletion oflexical access

Effects of word frequency on eye-movements

Time between successive eye-movements in ms

Frequency

Session 3:Towards a model of reading: E-Z reader model

Parafoveal processing Readers spend time between completion of

lexical access to a word and next saccade in parafoveal precessing of the next word

(this way the model can explain spillover effect)


fovea ~ most sensitive part of the visual field (2 degrees either side of fixation point

parafovea (extending 5 degrees)

periphery

Session 3:Automatic processing

Word recognition is fairly automatic Reading is mandatory (cf. Stroop effect) How many mechanisms are involved?

Automatic processes: (fast, parallel, not prone to interference from other tasks, cannot be prevented, facilatatory)

Attentional (controlled) processes: slow, serial, error prone, uses up working memory (WM), often availble to consciousness, can involve inhibition)

Session 3:Priming

Priming Involves the presentation of an item A (prime) before

reaction to item B (target) is measured stimulus-onset asynchrony (SOA) facilitation vs. Inhibition

Form-based priming Semantic priming

Session 3:Priming

Context effects Semantic (associative) priming

Lexical decision task Decision time for target is shorter when prime is semantically

related (e.g. DOCTOR - NURSE)

Session 3:Priming

Priming from sentential context “It is important to brush your teeth every single

___!”

PS: Introduction to Psycholinguistics

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