Transcript Slide 1

The cognitive psychology of
language – 2
• Now that we know how
words are recognized
– How are they produced in the
first place?
• Word production is the process
of turning thoughts into sounds
– Concepts  phonemes
• This process is a little complex
– Take into account both
semantics and syntax
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Choosing the right word
• Syntax plays a large role
– Adverb, noun, verb? - depends
on how far along your sentence
you are
– Tense and number : “All your
base are belong…”
• Semantic context also plays a
role
– If you have used a word before,
replace with a pronoun
• Semantic priming will ‘force’
certain words
– Increase the probability of a
group of words being chosen
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Lexicalisation
• Once you have chosen the
concept, convert it to sounds
– Lexicalisation
• A two stage process
– Stage 1: Concept activates a
lemma which has a semantic
representation and syntactic
information (‘lemma selection’)
– Stage 2: The lemma activates
the lexeme, a phonological form
of the word (‘lexeme selection’)
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Tip-of-the-tongue
• Evidence for the 2-stage model
comes from the tip-of-thetongue state
– Unable to retrieve a word even
though you know you know it!
– Can occur with extremely
common words
• Different from forgetting a word
– Completely forgetting would be a
failure at lemma selection
– Failure at lexeme selection leads
to tip-of-the-tongue state (know
the word but cannot find the
sounds to say it)
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Sentence
comprehension
• Understanding sentences is
quite complex
– A lot of meaning must be
extracted from the syntax
The teddy bears beat up the emu.
– Who did what to whom?
– Did it happen now, or before?
– Did it hurt the emu?
– Was it a fair fight?
• Need syntactic, semantic and
contextual knowledge
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Researching sentence
processing
• Extremely difficult
– Process if very fast, automatic
and pre-conscious
• Look for how hints in how it
fails
– Same as perception research:
try to fool the system and see
how it reacts
– Make use of ambiguities in
language rather than illusions
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Ambiguities in language
• Two forms of ambiguity
– Structural ambiguity (ambiguity in
syntax)
– Lexical ambiguity (ambiguity in
semantics)
• Structural ambiguity
The emus bought the teddy bear traps.
• Lexical ambiguity
The priest married my sister.
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What ambiguities say
about processing
• Sentences are processed
according to the “immediacy
principle”
– Figure what each word does as
we go along
The horse raced past the barn fell
• Make assumptions about
sentence meaning as we go
– eg. assume the first verb we
hear is the main verb
– Generally works because
expectations are based on
experience with real sentences
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Evidence for processing
immediacy
• Surprise expressed by people
at garden-path sentences
The emu sold the honey farm for a
lot of money wanted to kill the
teddy bear.
• Eye fixation studies
– A lot longer is spent processing
the second verb
– The confusion causes people to
stop reading and reconcile the
second verb with the previously
read part
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Processing syntax
• Sentence parsing can be
thought of as recursively
applying a set of rules to a
sentences
– Phrase structure rules
• These rules have been defined
by linguists
– Expresses the hierarchy well
– Drawn as phrase trees
– Conveys the relationship
between surface and deep
structure
– Separates semantic and
syntactic structure well
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Phrase tree
example
sentence
verb phrase
noun phrase
article
noun
verb
noun phrase
article
The
emu
loaded
the
noun
shotgun.
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Do we build trees when
parsing?
• It doesn’t look like it
– Sentences which are
syntactically different are very
similar in meaning
The teddy bears built the pipe-bomb
The pipe-bomb was built by the teddy bears
• Fodor: we use a series of
heuristics (rules of thumb)
– Noun-verb-noun is usually active
voice, subj-v-obj
– A ‘minimal effort’ approach (add
new words into the structure
which requires least effort to
process
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Sentence production
• Putting complex ideas into
words
– Include notions of time, politics,
semantics
• Studied by looking at slips of
the tongue
– When you say something other
than what you meant!
– Actually quite systematic
– Involve swapping one word, or
phoneme for another
– Categorised by Garrett (1975)
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Slips of the tongue
(Garrett, 1975)
• Anticipation error
– Shoot the emu!  Emu the emu!
• Word exchange
– Buying a nuclear scientist a drink  Buying a
drink a nuclear scientist
• Perseveration
– We will steal the uranium shipment  We will
steal the sturanium shipment
• Word substitutions
– The CIA planted a listening device  The CIA
planted a talking device
• Morpheme exchange
– The emus reinforced their houses  The
emus housed their reinforcements
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Garrett’s model of
sentence production
(1975)
• A state-based information
processing model
– ‘assembly line’ model
• Four states which transform the
intended message into speech
• Derived from study of slips
– Each slip must come from a different
sub-process
• At each transition, the message
can become garbled
– Slip of the tongue; one type per
transition
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Garrett’s model
State 1: Message Level
State 2: Functional Level
Word substitution slips
State 3: Positional Level
Sound exchange slips
State 4: Phonetic Level
State 5: Articulation Level
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1: Message Level
• The idea is conceptualized
• Completely abstract
(mentalese?)
2: Functional Level
• Match semantic & thematic
concepts to abstract ideas
– Actors, objects, etc.
• Word substitution (content)
slips can occur
– Because you may pick the wrong
semantic carrier for the idea
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3: Positional Level
• Syntactic structure is used to
order and modify the words
• Sound exchange slips can
occur
– Because syntactic modification
needs sounds to be added to
words
4:Phonetic Level
• Convert words into phonetic
representations
• Tip-of-the tongue problems can
occur
– Fail to match lemmas with
lexemes
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Is speech production
linear?
• Some debate
– Do the levels interact with each
other?
– The teddy bears’ defense is
strormidable – a mixed error
(phonological & semantic)
• Dell (1986) – suggests an
interactive network to account
for this
– A connectionist model
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Dell’s idea
• A parallel distributed interactive
model
• The message begins as
activation to concept nodes
(high level)
• Activation spreads downwards
to activate other nodes
– These include nodes that
encode syntactic structure
– The most activated nodes at the
end is the sentence that is
produced
– Can lead to errors
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Connectionism and
recursion
• Connectionist models have not
done well in explaining
recursion
– Computer models of maths
formulas are quite awkward
– Simple rule based systems fare
better
• Connectionist systems dno’t
deal well with substitution
grammar
– The <clause> was shot by the
<clause>
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