Transcript Week 8 - University of Toronto

Week 8
Outline
• Evolution
• Characteristics of Language
• Children’s language development
– (phonology, morphology, syntax, semantics, pragmatics)
• Theories of language acquisition
• Bilingualism Part I
Evolution
• Modern humans appeared 150 000 years ago
• All technological advances appear to have occurred in
the last 40 000 years
Brief History of Human Evolution
Advances in
stone tools
Fire
Art
Cities
Earliest
Homonid
Fossils
3
Australopethicus
Africanus
Brain expansion
2
Homo
Erectus
1
Neanderthal
Present
4
Earliest stone
tools
Homo
Sapiens
Evolution
•
•
Modern humans appeared 150 000 years ago
All technological advances appear to have occurred in
the last 40 000 years
• Appearance of speech may have been related to
sudden changes in vocal apparatus
1. Short, rounded tongue
2. Larynx is lower in throat than in other previous
species
These changes allow for greater control over vocal
apparatus, and hence more sounds can be made
Evolution Con’d
Two theories of the evolution of language:
• Discontinuity Theory
– Believe that language is unique to humans, didn’t evolve
over time, but happened abruptly, reflected by sudden
changes in the vocal apparatus that allowed speech
• Continuity Theory
– Believe that language occurred very gradually, is evolved
from calls and gestures of ancestors, and came from
gradual increase in brain size; changes in VA just allowed
it to happen
Attempts to teach our relatives language
• Vicki
– Tried to get her to speak;
Failed
• Washoe
– Learned a small number of
signs
• Nim Chimpsky
– Failed to do anything but
imitate and repeat same signs
• Kanzi
– Successfully acquired Yerkish
• Chantek
– Successfully learned sign
Primate Language, con’d
• Attempts at teaching primates language are
moderately successful
• Takes A LOT of time
• Typical communication involves reinforcers like
food (Chantek e.g.)
• Does not appear to be a natural acquisition for
primate species
Characteristics of Language (Hockett, 1961)
• Semanticity
– Symbols convey meaning
• Arbitrariness
– No resemblance between word and referent
• Discreteness
– Signals don’t vary continuously
Characteristics of Language con’d
• Duality of Patterning
– Contingent on discreteness, words have both a
whole form, and can be broken down
• Productivity
– Highly creative, can make new sentences all the
time
• Displacement
– Talk about things not in front of us
– Reflect on past or future events
Does anyone else have language?
Semanticity
• Honeybees: yes, a waggle
indicates a food source,
so it has meaning to the
members of the hive
• Vervets: yes, their calls
mean something to the
kin and group mates
Arbitrariness
• Honeybees: No, the
dance is at an angle
relative to food source
and sun
• Vervets: yes, calls have
nothing to do with
predators they refer to
Discreteness
• Honeybees: yes and no:
waggles for near and far
are discrete, but waggle
more for certain
amounts
• Vervets: yes: one call
indicates one thing, and
another call another
thing
Duality of Patterning
• Honeybees: no
• Vervets: no
Productivity
• Honeybees: Yes, can
signal new locations, and
different kinds of
location
• Vervets: No, productivity
would endanger kin!
Displacement
• Honeybees: yes, but in a
limited way
• Vervets: no, calls are
never made in absence
of predator
Other species?
• African Elephants
• Whales
• Dolphins
Children’s Language Development
Stages of Phonological Development
Stage
Features
Reflexive Crying (0-8 weeks)
Mainly crying and vegetative sounds
Cooing and Laughter (8-20
weeks)
Vocal play (16-30 weeks)
Mainly vowel sounds and laughter,
more social
Reduplicated babbling (25-50
weeks)
Jargon (9-18 months)
Make many sounds over and over,
like bababa
Transition between cooing and
babbling; some syllables
Speech-like sound patterns emerge
Phonological development con’d
•
•
•
•
Notice overlap of phases in infancy
Children make mistakes in phonology
Deaf infants stop after stage 3
Receptive VS Expressive Language
Role of Intentionality
• Must to intend to communicate in order to
communicate
• Earliest intention is non-specific and not goalrelated, like play, joint attention
• By 8 months, communicative gestures are in
place, which are gradually replaced by words
Language Perception
• Problem of segmentation”
– “Do you want some mango?”
– “What’s a semmango?”
• Infants very good at separating sounds of
speech (Aslin’s work)
• Prosodic Bootstrapping Hypothesis
• Motherese
Morphological Development
• When speech begins it is “holophrastic”
• Morpheme = smallest unit of meaning
• Relatively universal acquisition order of morphology
(e.g. present tense 1st, possessives later, contractions
last)
• Ways to measure: MLU, conjugation
• Mistakes: Overregularization (goed, wented, feets)
Syntactic Development
• Initially, speech is telegraphic but gets more complex, and
eventually we need…
• Syntax = knowledge of sentence structure and how things go
together
• Sentences get bigger between 2 and 4
• Syntax development in predictable
– Start using Wh- questions (where first, then why and how)
– Use more negations
– Produce more complex sentences
Semantic Development
• Children acquire words rapidly
– At 18 months have about 50 words
– By 24 = 200 words (37 words/month)
Cumulative vocabulary
Patterns of lexical growth
140
120
100
Spurt at 16mt
Spurt at 19.5 mt
Spurt at 22 mt
Gradual word learner
80
60
40
20
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
2.5 week intervals starting at 14
months
Lexical growth from 10-50 words
Percentage of total
vocabularies
70
60
50
General Nominals
Specific Nominals
Action words
Modifiers
Others
40
30
20
10
0
10
20
30
Word level
40
50
Semantic Development
• Children acquire words rapidly
– At 18 months have about 50 words
– By 24 = 200 words (37 words/month)
• Seem to use fast-mapping (Ability to learn new words
based on very little input)
– Earlier words very context-bound; this changes in second
year
• Overextension and underextension
• Problem of mapping (knowing “shoes” doesn’t just
refer to laces)
• Seem to have strategies for assigning meaning to words:
Processing constraints used to assign meaning to
words
• Object Scope Constraint
– Word refers to whole object and not parts
• Taxonomic Constraint
– Words label categories of similar objects with similar perceptual features
• Mutual Exclusivity
– Each word has one label and that different words refer to separate nonoverlapping categories
Can you show me a dax?
Semantic Development
• They use Syntactical Bootstrapping: they will use
word order to assume meanings of words
This person is nissing.
Can you show someone else nissing?
Children will use the syntactic cue from the sentence to
determine which part of the picture was “nissing”
Pragmatic Development
• By the age of 3, children are adept with their audience
• They know to phrase requests in a certain way:
– 3 year old: “Every night I get an ice cream”
– Babysitter: “That’s nice”
– 3 year old: “Even when there’s a babysitter I get an ice
cream”
They understand that not everything is literal, and that some
questions are rhetorical
By 4, they adapt their speech when speaking to younger
siblings
Theories of Language Development:
Nativism
•
•
•
•
Based on Chomsky’s linguistic theory
Surface VS Deep structure
Deep Structure = Universal Grammar
Posits the Language Acquisition Device to acquire
surface structure
• We have to learn principles and parameters of our own
specific language
– E.g. Head-first VS head-last
– Pro-drop languages
Lenneberg points out features of language that make
it uniquely human:
•
•
•
•
•
•
Species Specific
Species Uniform
Difficult to Delay
Regular Sequence
Anatomical Structures related to language
Genetically based language disorders (disorders that
run in family)
“Speech is Special” hypothesis
1.
2.
3.
4.
5.
6.
7.
8.
9.
Different areas light up during auditory vs. speech tasks
Critical period for language but not hearing
Dissociation between speech and language and hearing
functions in aphasics
Right ear advantage in humans
Phonetic mode of perception
Acoustic trading
Categorical perception
Audiovisual speech perception and intermodal integration
Symmetry between production and perception
More evidence…
• We are able to create language from nothing
• Pidgins
– Structurally simple communication systems arising from 2
people who share no common language
– Hawaiian Pidgin
• Creoles
– Languages formed when pidgin is developed into a
complex, true grammatical language
– Children of above
• Deaf e.g.
– Nicaraguan Sign Language
The Critical Period Hypothesis
• Children appear to learn language better than adults
4 lines of evidence:
• Feral or socially deprived children
– Never acquire language properly
• The case of Second Language Acquisition (Johnson &
Newport)
• Deaf Children
– Can never learn traditional signing systems
• Brain Plasticity
– If injured when young, other areas of the brain will take over
Potential Problems with Critical Periods
• Feral children?
• Johnson & Newport VS Bialystok & Miller
– Results depend on languages tested (Spanish VS
Korean)
– Results vary when modality is varied
• Problems with nativism in general
– Categorical perception of phonemes AND signs
AND colour, and other animals do it
– Not enough explanatory power
Theories of Language Development 2:
Social-Interaction Hypothesis
• Most common name associated: Bruner
• No innate mechanisms
– rather language arising from our social interactions, and out
of social necessity
• Parents use the Language Acquisition Support System
• This allows adults to speak more slowly, simpler, fewer
words
• Suits the limited information processing capacity of
younger children
Social Interaction Hypothesis
Lines of evidence:
• Pre-linguistic turn-taking: promotes and encourages language
acquisition
• Child-directed speech (main features)
– We use higher frequencies
– More various frequencies (highs and lows)
– More rising frequency contours (going from low to high)
– Regulates baby’s mood, behaviour, and attention, and relays
mom’s mood
– Restricted vocabulary, paraphrasing, limited to context
Social Interaction Hypothesis
• As we mature the people around us will speak faster,
and in more complex sentences
• Same phenomenon as when we speak English to a
presumed foreigner
• Language comes about from social interaction and out
of social necessity
Theories of Language Development 3:
Locke’s Neurolinguistic Theory
1.
Vocal Learning (onset prenatal)
1.
2.
2.
Utterance acquisition (onset 5 to 7 months)
1.
2.
3.
Utter words and short phrases, but really hold no meaning
Again, revolves around Social Cognition
Grammatical Analyses (onset 20-37 months)
1.
2.
4.
Hear sounds, learn them, prefer them
Revolves around social cognition
Acting on info stored from previous phase, try to extract rules
Focus on analysis
Elaboration and Integration (onset 3 years+)
1.
2.
Processing both social and grammatical info
Can take in new info and organize it
Neurolinguistic Theory
• Posits an internal innate grammatical module that kicks in in
the third phase, and is able to interpret a lot of info
• Some supporting evidence:
– Correlation between vocabulary size and correct grammar
usage in preschoolers
– Explains impoverished L2 acquisition: Missing too much info
from phases 1 and 2 to be able to get to phase 3
See bidirectional relationship of structure and function,
where innate module won’t kick in without having a need
to function
Problem: Black box, innate mechanism
Bilingualism Part 1
• What are effects of speaking 2 languages from birth?
• Does not appear to be at a linguistic level
– Some languages are better at some tasks (E.g. Spanish with
phonological tasks)
– No reliable advantage in aspects of language development
Bilingualism, con’d
• How do we assess whether a child is bilingual?
– Peabody Picture Vocabulary Test (Receptive)
– Video or Storytelling (Expressive)
– Parental report
Bilingualism con’d
• Metalinguistic awareness: what we know about
language, grammar, etc…
• Perhaps learning 2 languages will increase
awareness of language generally
• Tasks:
– Piagetian Sun-Moon Task
– Grammaticality Judgments
– Moving Word
Sun – Moon Problem
If everyone agreed to change the names for the
sun and the moon, so we would call the sun, the
moon, and the moon, the sun, what would be up in
the sky when we go to bed at night?
Answer: the sun
What would the sky look like?
Answer: dark
Scores on Sun-Moon Type tasks
Bialystok, 1988
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Monolingual
Early bilingual
Late bilingual
Grammaticality Judgments
Correct: Apples grow on trees.
(Right)
Incorrect: Apples growed on trees.
(Wrong)
Anomalous: Apples grow on noses.
(Right)
Wrong: Apples growed on noses.
(Wrong)
Grammaticality Judgments (7-year-olds)
Bialystok, 1986
6
5
4
*
3
Monolingual
Bilingual
2
1
0
Correct
Incorrect
Anomalous
Wrong
Grammaticality Judgments (9-year-olds)
Bialystok, 1986
6
*
5
4
Monolingual
Bilingual
3
2
1
0
Correct
Incorrect
Anomalous
Wrong
Moving Word Task
dog
dog
Proportion correct in Moving Word Task by
age and group
Proportion Correct
1
0.8
Monolingual
French Bilingual
Chinese Bilingual
0.6
0.4
0.2
0
4 years
5 years
Age
Moving Word Task by Language Group
Proportion Correct
1
0.8
Monolingual
French Bilingual
Chinese Bilingual
Hebrew Bilingual
0.6
0.4
0.2
0
4 years
5 years
Age
Conclusions about Language Development
• Remarkable regularity across children and cultures in
rate of development
• Mechanisms are as of yet not agreed upon
• Different life experiences like bilingualism can alter
how we understand aspects of language