Transcript Health, Nutrition and Feeding

Language: Individual differences
Daniel Messinger, Ph.D.
Language overview review
n
n
n
n
What is the normative course of infant language
development?
How do infant cries develop (directed and
undirected)?
What are the stages of development of non-cry
vocalizations?
What are some early milestones of verbal
development (verbal development involves
words)?
2
Perspective
n
Last time
–
–
n
Features of language that all infants develop
Focus on production: speech
This time
–
How infants differ in learning language
n
n
n
Differences in learning to hear a first language
Differences in learning to talk a first language
Autism and deafness
3
Today’s questions
n
How does the ability to distinguish between nonnative speech sounds change in the first year?
–
–
n
n
n
What does this mean about development?
Can distinctions between non-native sounds be taught?
How is language experience associated with later
child language competence and IQ?
How is socioeconomic status associated with
differences in language experience?
What does cochlear implantation teach us about
language development?
4
Consider the spoken tokens of
“doll.”
n
n
To a Hindi speaker, the difference between
the “d” sounds in “this doll” versus “your
doll”—a phonetic contrast between a dental
[d̪al] versus a retroflex [ɖal], respectively—
would signal two possible word forms
(either lentils or branch).
In English, both of those “d” sounds signal
just one possible word form—phonetically
labeled as an alveolar [dal].
5
Different languages provide
different phonetic experiences
6
What’s going on?
n
n
English-learning
infants hear Hindi
contrast better than
English-speaking
adults
Almost as well as
adult Hindi-speakers
100
90
80
70
60
50
40
30
20
10
0
Hindi Adults
Infants
English Adults
Dentral vs. retroflex "t"
7
Distinguishing between nonnative speech sounds in 1st year
n
At birth, infants are capable of discriminating all
phonetically relevant differences in the world’s
languages
–
n
n
They perceptually partition the acoustic space
underlying phonetic distinctions in a universal way.
By 6 months of age, infants raised in different
linguistic environments show an effect of
language experience.
Their representations are becoming language
specific
8
How does this develop?
n
100
90
80
70
60
50
40
30
20
10
0
Infants lose this ability
in the first year of life,
especially toward one
year of age
6-8 Months
8-10 Months
10-12 Months
Dentral vs. retroflex "t"
9
What this mean for development
n
n
Very young infants can discriminate a wide range
of phonetic contrasts in a variety of languages
Between 1 & 12 months, infants
–
–
increase knowledge of which syllables follow which in
their native language
but lose ability to make contrasts that do not occur in
their native language
n
n
/r/ vs. /l/ . /b/ vs. /v/ . Te’ vs. te, tu’ vs. too
Development involves relatively permanent
change, but not always improvement in all things.
10
Parallels in speech production
•
•
n
Infant babbling shows little influence of
native language.
Once the infant forms his/her 1st words than
the sounds produced conform more closely
to those of the native language
This corresponds to the stage at which
infants begin to show language-specific
sensitivity (10-12 months).
11
Possible roles of experience
Induction – prior experience with a language is
necessary because perceptual capability depends
entirely on environmental input
Attunement – experience makes possible the full
development of a capability.
Facilitation – experience effects only the rate of
development of a capability.
Maintenance/loss – the ease in which a capability is
fully developed before the onset of experience, but
experience is necessary to maintain the capability.
Maturation – development of a capability
12
independent of experience
Perceptual Magnet Effect
n
n
Instances of sounds
that belong to a
category are drawn
toward the Prototype.
Physical (acoustic) vs.
perceptual maps
–
the latter differ for
speakers of different
languages
13
Can distinctions between nonnative sounds be taught?
n
n
n
Cheour has experimentally produced this
“development”
In sleeping neonates
Using changes in neural responses to
sounds as an outcome variable
•
http://www.med.cornell.edu/news/press/2002/feb_22_
newborn.html
14
How sleeping babies learn
n
The babies had
electrodes placed on
their scalps, and
speakers near their
heads gently played
a randomized
sequence of two
similar Finnish vowel
sounds as they
slept: a "standard"
sound, /y/, and a
"deviant" sound, /i/.
15
Mismatch Negativity (MMN)
n
n
“ when the brain
hears the standard
sound, there is a
certain response in
the brain, and when
it hears the deviant
sound, there is
another response.
Subtracting the
responses to the
deviant from the
responses to the
standard produces
the MMN.”
16
Training
n
n
No initial MMN for any group (N=15).
Over the following night, for between
two-and-a-half and five hours, the
experimental group had a "training"
session of exposure to the two sounds.
–
n
/y/ vs. /i/.
One control group did not have this
exposure, and the other control group
heard two different sounds, /a/ and /e/.
18
Results
n
n
The experimental group showed
significant mismatch negativity to the
deviant sound.
The babies had learned to distinguish
between these two Finnish vowels.
–
n
Persisted for at least 24 hours.
The two control groups showed no MMN
to the deviant sound.
19
Conclusion
n
"We have shown that newborns
can assimilate auditory information
while they are sleeping, suggesting
that this route to learning may be
more efficient in neonates than it
is generally thought to be in
adults."
•
n
Cheour
Is this learning?
22
23
Reviewing the power of language
o
More maternal vocalizing at 1 month
o
o
Associated with vocalizations at 8 & 24 months
and with socioeconomic status
Also predicts greater adolescent intelligence
o
R2 = .22 for gazing and maternal vocalizations
120
110
100
90
80
Long Infant
Long Infant
Short Infant
Short Infant
Fixation /
Fixation /
Fixation /
Fixation /
Low Maternal High Maternal Low Maternal High Maternal
Vocalization Vocalization Vocalization Vocalization
26
Overview
n
n
n
Socioeconomic differences in how folks
talk to their kids
What impact might it have?
How is language experience associated with
later child language competence and IQ?
27
Socioeconomic status
differences in language
experience are associated with
later child language
competence and IQ
n
Meaningful differences in the everyday
experiences of young American children. Hart &
Risley (1995). Baltimore, MD: Brookes
Publishing Co
n
Some text from summaries by Susan Brunner, Dahra Jackson,
and Amy Vaughan
28
Participants
n
Longitudinal project from 9-10 months infant age
up until 2-2 ½ years later
–
–
–
n
42 families observed for one hour every month, at
home, in natural settings
recruited from birth announcements, friends and
families at University pre-school, WIC meetings, and
state records
all but 8 families were intact, all but one had a male
figure involved
13 upper SES, 10 middle SES, 13 lower SES, and
6 families on welfare; all “well-functioning”
29
Data collection
n
Observers transcribed and audio-recorded all
verbalizations and interactions that would have an
effect on another person; never interacted with
child, but responded to parents
–
–
–
Observers assigned to families for entire study, when
possible, and similar to family in terms of background
no drop-outs after first year, reliability on coding and
observations was adequate
words coded as part of speech, episodes coded by type,
and speaker coded; dictionaries compiled for each
speaker (all on computer)
30
Commonality
n
Despite how strikingly different the
families were in how much talking and
interaction typically went on in the home,
just socializing during everyday activities
was sufficient for all children (regardless
of SES) to learn to talk by age 3.
31
42 Families and the Differences
Among Them
n
n
differences observed in family language style:
parents’ language seemed to reflect the number
and variety of behaviors they had for dealing w/
their children
some families talked more than others, and this
was variable within families from month-tomonth, but stable over the 3 years
–
birth order and family size affected the amount of talk
each child received, but did not affect the total amt. of
talk
32
n
SES seemed to make the biggest contribution to both amount
of talk and time spent in interactions, with hi SES at an
average of 482 wds/hr and 48 mins/hr, and welfare families at
197 wds/hr and 17 mins/hr
33
Language and SES (class)
n
n
n
Children from all backgrounds have the same
kinds of everyday language experiences.
But more economically advantaged children differ
in the amount of these experiences; it is the
frequency that matters.
More opportunities for learning language occur
when children engage in many and varied
interactions with other people; families tend to be
consistent in the opportunities they provide for
their children.
34
Talk that teaches talk
n
THEY JUST TALKED
–
n
THEY LISTENED
–
n
n
To add information and prompt elaboration
THEY TRIED TO BE NICE
–
n
parents talked beyond what was needed to provide care
When enforcing a rule
THEY GAVE CHILDREN CHOICES
THEY TOLD CHILRESN ABOUT THINGS
–
Things worth noticing or remembering (Halloween)
35
Quantity of language: Nouns,
adjectives, and adverbs to child
36
Being positive
n
Repetitions,
extensions,
expansions,
confirmations,
praise, approval
over all
feedback
(including
imperatives,
criticisms, etc).
37
Relating things and events
n
Nouns, modifiers, and
past-tense verbs
divided by number of
utterances per hour
38
“Can you. . . ?”
n
Proportion of yes/no
questions over yes/no
questions and
imperatives
39
Responsiveness
n
n
‘Ok’ ‘I see’
% of responses not
preceded by an
initiation
40
How language experience is
associated with later child IQ
n
n
“Parenting” =
Language diversity +
feedback tone +
symbolic emphasis +
guidance style +
responsiveness
Predicts between and
within SES groups
41
Language experience makes the
difference
42
Implications for intervention
n
n
n
n
‘To intervene with vocabulary growth rate …
increase the experiences available to the children
Limited success … ultimately the growth rates
increased only temporarily.
Could easily increase the size of the children’s
vocabularies, could not accelerate the
developmental trajectory.’
“Removing barriers and offering opportunities and
incentives is not enough to overcome the past, the
transmission across generations of a culture of
poverty.”
43
Is environmental influence global or
specific?
n
n
n
We know that there are differences in language
development across SES
Mothers are primary source of language-experience
Does maternal speech mediate the relation between SES
and child vocabulary development?
The Specificity of Environmental
Influence: Socioeconomic Status Affects
Early Vocabulary Development Via
Maternal Speech
Erika Hoff
Maternal speech fully mediates
relationship between SES and
child vocabulary!



SES -> 5% of variance in child vocabulary
SES significantly associated with maternal speech
MLU -> 22% of variance in child vocabulary


When removed, only 1% of variance explained by SES
So…there are 2 processes going on
 1. SES affects maternal speech



Childrearing beliefs
Time availability
2.Maternal speech affects language growth

Provides data for child’s word-learning mechanisms



Longer utterance -> more variance in word types (richer vocabulary)
Longer utterance -> more info about meaning
Longer utterance -> richer syntax
Support environmental
specificity model
n
n
Vocabulary development depends on
specific properties of language experience
Implies that enriching language experience
can increase vocabulary development for
low-SES kids
Niparko et al., 2010
Romero
Earlier implantation, earlier
language gains
Romero
Receptive Language
Romero
Expressive Language
Romero
Other findings
n
n
n
Higher parent-child interactions and higher
socioeconomic status were associated with
greater rates of language learning.
Bilateral implantation was not associated
with an increase in language acquisition.
Gender was not associated with an increase
in language acquisition.
Romero