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Cognitive Psychology C81COG2. Cognitive Processes In Word
Recognition & Reading
Dr Jonathan Stirk
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Some background reading
Chapter 2– Underwood, G & Batt, V (1996). Reading and
understanding. Blackwell: Cambridge, USA.
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Overview & Questions
How do we recognise visually presented words?– BOAT vs. BORT
Some words are recognised more easily than others– Some sources of difficulty
Word recognition by word detectors– A theory of word recognition
Do we recognise whole words, or their components?– Words and morphemes
Word frequency and context as examples of difficulty– How do the theories provide explanations?
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Word length– Longer words take longer to recognise
Morphemic complexity– The more morphemes in a word, the more difficult it
will be to recognise the word Word frequency
– Commonly used words are recognised more easily than infrequent words
Context of presentation– Predictable words are recognised more easily than
those in neutral or incongruent contexts Orthographic irregularity
– Words which obey the ‘spelling-to-sound’ rules of the language are easier to recognise (SHIP SHOE SHARE vs. COVE, LOVE)
Recognising Words (Some Causes of Recognition Difficulty)
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Treisman’s (1960) Model of Attention(Also Formal Model of Word Recognition)
Discrimination of physical characteristics
Listener’s own name
“DICTIONARY” ANALYSIS OF MEANING
SELECTIVE FILTER
Attended message
Unattended message
NB- the analysis of meaning is aided by word detectors called “dictionary units”
We have an internal store of known words – LEXICON
Treisman’s model accounts for frequency and sentence context effects
Word detectors are ‘dictionary units’ in her model
B
CA
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Morton’s (1969, 1979) ‘logogen' System
LOGOGENS as word detectors
c.f. Treisman's dictionary units
Each logogen has an activation threshold which needs to be met before it fires
Parallel model
Response
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An analogy of Logogen model!
You can think of a logogen as a collector of evidence
When enough evidence is collected (i.e. the strength of the hammer hitting the bell!) then the threshold is reached, the logogen fires and the word is recognised
Activation Threshold
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Words and Morphemes (What's in Your Mental Dictionary?)
Line 1 free morpheme
Lines 1 free morpheme + 1 bound morpheme
Underline 2 free morphemes (compound word)
Base + s "inflectional" morpheme added
Base + ment "derivational" morphemes Wait + ing added
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Evidence for the Use of Morphemes in Word Recognition
Taft & Forster (1975) - lexical decision task
"Is the following letter string a word or not?"Tible
Cat
Negative responses are slower for certain kinds of non-words:
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Evidence for the Use of Morphemes in Word Recognition
E1 pertoire < juvenate real word stem which does not exist as free morphemes (bound stem)
E2 bescue < bevive non-words formed as below
REvive becomes BEvive (vive is a real stem)REscue becomes BEscue (scue does not
exist as a real stem- pseudostem)
Prefix (meaning to repeat)
Non-Prefix (illegal prefix)
Inappropriate but possible/legitimate prefix
Affix stripping (Taft, 1981)
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From Underwood & Batt p.65
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Frequency Effects in Word Recognition
Common, high-frequency words (e.g. RAT) are
recognised more easily than uncommon, low-
frequency words with the same number of
letters (e.g. GNU)
1. The girl noticed the rat run across the
playground
2. The girl noticed the gnu run across the
playground
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Frequency Effects in Word Recognition
For words presented against noisy backgrounds, recognition accuracy is best for high frequency words
Faster responses are given to high frequency words in tasks involving
–Lexical decisions task (is this a word or not?)
–Naming task
–Category decision task (e.g. Does the word name a piece of furniture?)
CAT, FEET, CHAIR, COMA, TABLE
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Models of the Frequency Effect(Why Are Frequent Words Easier To Recognise?)
Threshold Models (e.g. Treisman, Morton)
Treisman's "dictionary units" have individual thresholds for activation
Morton’s logogens do too
High frequency words have lower thresholds, and therefore require less stimulus information before the word detector is activated
– High frequency words have a lower threshold for firing
–E.g. cat vs. cot
‘cat’[kæt]
‘cot’[kot]
Low freq takes longer
Thanks to Julie Simner (Edinburgh) for this analogy
An alternative model of word recognition
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Access Files (like card file system in a library)
Visual code Auditory code
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Models of the Frequency Effect
Search Models [e.g. Taft, Forster (autonomous serial search model]
Recognising words is a matter of searching through our word memories, looking for a match between words we know and the word newly presented
On the basis of probability, we first search frequently used word memories
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Context helps word recognition
Study: TULVING & GOLD (1963) Subjects read an incomplete sentencee.g "The skiers were buried alive by the sudden
__________"and then attempt to recognise a single word,. e.g avalanche (relevant context) orinflation (misleading context)
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Tulving & Gold (1963)
Q. Will increasing the amount of semantically related information that is available before the target word is presented affect the minimum amount of time needed to identify the word?
A target word is presented at varying exposure durations, starting too brief for recognition, and increasing until the word is recognised
They measured the stimulus exposure necessary for recognition with relevant context and with misleading context
The amount of context (relevant or misleading) also varied (up to 8 words of context)
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Relevant context helps recognition
Misleading context makes recognition difficult
Exposure duration necessary for recognition
of the word (msec)
40
90
Amount of context provided (no. of words)
0 8
Tulving & Gold (1963)
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Models of the Context Effect
Threshold models– The cognitive component of the logogen model
explains how sentence context can affect recognition
– The semantic information from the sentence partially activates logogens, lowering their threshold
– This decreases the amount of information needed from the word itself to fire the logogen