Transcript An introduction to the cognitive psychology of language

An introduction to the
cognitive psychology of
language
• These lectures tie into Groome
chpt 8 – 9 (pp. 215-260)
• Recommended reading:
Chapters 12-14 of
Eysenk, M.W., Keane, M.T. (1995)
Cognitive psychology: A student’s
handbook. Hove, UK.: Psychology Press
• Chapter 9 of
Martindale, C. (1991) Cognitive
psychology: A neural-network
perspective. Pacific Grove, CA.:
Brooks/Cole
1
Language vs.
Communication
• Many animals communicate
– Call for danger, signal where food
is, etc
– Ravens have individual names for
their mates
• Linguists: Only humans have
language
– Much more than just
communication
– Pinker: bids have a flying instinct,
humans have a language instinct
• What sets language apart from
communication?
2
1. Language consists of arbitrary
semantic symbols
Rabbit
Conejo
Usagi
Kanninchen
Cuniculus
Arbitrary symbols
“look at this”
lobster
“grab hold of
this”
Descriptive symbols
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2. The units of language are
discrete
Discrete
It is my book.
Es mi libro.
Ore wa hon desu.
Es ist mein Buch.
The axis of
the bee’s
dance
shows the
direction to
the food
source
Continuous
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3. Language has displacement
•
•
Talk about stimuli which are not
present
“The yellow elephant eats dancing
peanuts.”
4. Language is productive
•
Produce novel utterances which can
be understood (see the elephant
sentence!)
5. Language is iterative
•
•
•
Stick sentences together using
conjunctions, as many as you like.
Grow sentences from the end
“I like eating pizza and drinking coke
and swimming in the sea and
watching TV and listening to jazz and
flying kites and …..”
5
• Language is recursive
– You can make longer sentences
by embedding clauses to replace
words
– Grow sentences from the middle
• The elephant eats peanuts
• The elephant, who is yellow,
eats peanuts
• The elephant, who is a mild sort
of yellow, eats peanuts
• The elephant, who is a mild sort
of colour similar to mustard,
eats peanuts
• …..
6
Rules and objects
• Words carry meaning on their
own
• Semantics – the meaning of
words on their own (eg. Rabbit
means a small fuzzy creature
that eats carrots)
• Sentences only carry meaning
if the words are arranged in a
particular order
• Rules of correct word
arrangement are called syntax
7
Syntax is just a
convention
• English has a subject-verb –object
(SVO) syntax
– ‘the boy kicked the dog’
– ‘Newspapers will print the report’
• Japanese has a subject-object-verb
(SOV) syntax
– ‘the boy dog kicked’
– ‘Newspapers the report print will’
8
Chomsky & Syntax
• Noam Chomsky
realized that
language must
consist of a set of
general rules
– Otherwise, how do
you deal with new,
unfamiliar
sentences?
• The purpose of these rules is to
prevent speaker from generating
ungrammatical sentences
• To discover the syntax of a
language, linguists show speakers
sentences and ask if they are
correct
– ‘eat the boy the hotdog.’
– ‘The man hit the elephant.’
9
Surface & deep structure
• Chomsky (1956) argues that
sentences have meaning at two levels
– Surface level – includes the semantic
information
– Deep level – only the syntax
information (“universal grammar”)
– Same structure on a level can lead to
different sentences
Same at deep level, different at surface
level
The emu enjoys eating teddy bears.
The emu hates watching Oprah.
Same at surface level, different at deep
level
The emu ate the teddy bear.
The teddy bear was eaten by the emu. 10
Parsing sentences
• Decoding the syntax of a
sentence is parsing
• During parsing, no note is
taken of semantic meaning
– This makes it possible to parse
nonsense sentences
“Colourless green ideas sleep
furiously”
– This property allows for
ambiguity to creep into language
11
Parsing ambiguous
sentences
The big ones are shooting fish
Mod.
Noun
Verb
Noun Phrase
Noun
Verb Phrase
The big ones are shooting fish
Mod.
Noun
Noun Phrase
Verb
Noun
Verb Phrase
12
Resolving ambiguity
• Ambiguity arises from the fact that
the deep structure of both
interpretations is the same
– NP+VP
– But semantically they are very
different!
– To resolve the ambiguity we need more
information to select a surface
structure that fits
• This shows that parsing is done
before semantic interpretation
• Also, parsing is independent of
semantic analysis:
13
Sentence transformations
• Syntax gives us transformation
rules
– Convert from one type of
sentence to another
• English (question formation):
– Subj. Vrb. Obj. -> Aux. Subj. Vrb. Obj.
– “I ate the apple.” -> “Did I eat the
apple?”
• Japanese (question formation):
– Subj. Obj. Vrb. -> Subj. Obj. Vrb. [ka].
– “Ore wa ringo o tabemashita.” -> “Ore
wa ringo o tabemashita ka.”
14
Exceptions to transform
rules
• Most transformations have
‘exceptions’
– Times when the rule is not followed
– Eg. Conjugation of ‘to be’ – it is an
exception in almost every language
I type, you type, she types, we type,
they type, you(pl) type.
RULE: I <vs>, you <vs>, she <vs>+s, we
<vs>, they <vs>, you(pl) <vs>
BUT NOT:
I be, you be, she bes, we be, they be,
you(pl) be
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Why exceptions?
• Exceptions make it harder to learn
languages – so why?
– Languages have evolved to be
spoken, not to be learned.
• Exceptions seem to occur in the
most common verbs! (to be, etc)
– Deriving the rule takes time (and
effort)
– If it’s a common verb, then you will
waste a lot of effort deriving it each
time
– Much easier to store it
– To prevent the rule interfering with
retrieval, make the exceptions
extremely different from the derived
version
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