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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 wordsFaster 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