PS: Introduction to Psycholinguistics

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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
Experience
Object
Recognition
Perceptual
organization
Sensory
input
Buttom-up
processing - Visual
processing
originates from
sensory input
Session 3:
Visual processing
Prior Experience
Object
Recognition
Top-down
processing
Perceptual
organization
Sensory
input
Session 3:
(visual) word recognition
Word level
Letter level
Feature level
CAT
Assumption: word recognition sequential buttom-up-process
Session 3:
(visual) word recognition
Session 3:
(visual) word recognition
Word level
Letter level
top-down effects
(word superiority effect)
Feature level
buttom-up effects
Stimulus: COAT
Session 3:
(visual) word recognition
Session 3:
(visual) word recognition
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

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Brain imaging
Examining eye movements
Word identification tasks
Categorisation times
Tachistoscopic identification
Session 3:
(visual) word recognition/ methods
 word identification techniques

Naming task
Subjects name visually presented a words
 Naming 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

Session 3:
(visual) word recognition/ methods
 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


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(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:
(visual) word recognition/observations
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
Session 3:
Towards a model of reading
 But...




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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)
Session 3:
Towards a model of reading
 Problems for the simple model:


It is hard to see how readers could skip words
It takes about 150-200ms to execute an eyemovement program -> readers would waste time
waiting for their eyes to move
Session 3:
Towards a model of reading
 Advantages eye-movement recording:


It provides a detailed on-line record of attentionrelation processes
Unobstrusive
 Disadvantage

Hard to to be sure exactly what processing
occurs during each fixation
Session 3:
Towards a model of reading
 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
Session 3:
Towards a model of reading
 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
Session 3:
Towards a model of reading
 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
Time between
successive eyemovements in
ms
350
300
eye-movement
executed
completion of
frequency check
completion of
lexical access
250
200
150
100
50
0
1
2
3
4
5
6
7
8
9 10 11
Frequency
Effects of word frequency on eye-movements
Session 3:
Towards a model of reading: E-Z reader model
 Parafoveal processing

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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)
Session 3:
(visual) word recognition/observations
 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


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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
___!”
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