1. Language: Individual differences
Daniel Messinger, Ph.D.

2. Language overview review
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)?

3. Perspective Last time This time
Features of language that all infants develop
Focus on production: speech
This time
How infants differ in learning language
Differences in learning to hear a first language
Differences in learning to talk a first language
Autism and deafness

4. Today’s questions
How does the ability to distinguish between non-native speech sounds change in the first year?
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?

5. Consider the spoken tokens of “doll.”
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].

6. Different languages provide different phonetic experiences

7. What’s going on?
English-learning infants hear Hindi contrast better than English-speaking adults
Almost as well as adult Hindi-speakers

8. Distinguishing between non-native speech sounds in 1st year
At birth, infants are capable of discriminating all phonetically relevant differences in the world’s languages
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

9. How does this develop?
Infants lose this ability in the first year of life, especially toward one year of age

10. What this mean for development
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
/r/ vs. /l/ . /b/ vs. /v/ . Te’ vs. te, tu’ vs. too
Development involves relatively permanent change, but not always improvement in all things.

11. Parallels in speech production
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).

12. 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 independent of experience

13. Perceptual Magnet Effect
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

14. Can distinctions between non-native sounds be taught?
Cheour has experimentally produced this “development”
In sleeping neonates
Using changes in neural responses to sounds as an outcome variable

15. How sleeping babies learn
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/.

16. Mismatch Negativity (MMN)
“ 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.”

17. Language-specific phoneme representations in the infant brain
Development of language specific 'memory traces'
Infants: 6 months - 1 year 
Estonian and Finnish languages 
Analyzing mismatch negativity (MMN)
deviant vs. standard stimuli  
Fernandez

18. Training 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.
/y/ vs. /i/.
One control group did not have this exposure, and the other control group heard two different sounds, /a/ and /e/.

19. Results
The experimental group showed significant mismatch negativity to the deviant sound.
The babies had learned to distinguish between these two Finnish vowels.
Persisted for at least 24 hours.
The two control groups showed no MMN to the deviant sound.
Moreover, when the two sounds were presented to the experimental group at a different pitch, the experimental group was still able to distinguish between them.

22. Conclusion
"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."
Cheour
Is this learning?

24. Conclusions
Language-dependent memory traces emerge before the age of 12 months 
 MMN amplitude by the age of 1 year
   for native phonemes
   for non-native phonemes
The ability of infants to discriminate native speech sounds improves, while they lose some of their ability to discriminate non-native speech sounds 
Fernandez

25. A word on word learning
14-month-old infants can rapidly learn arbitrary associations between words and objects,
this ability appears to develop at about 14 months
only 14-month-old infants formed word-object associations but appeared to do so only when the objects were moving.
Although 8- to 12-month-olds did not form the associations, they appeared to process both the word and the object information.
Werker, J. F.; Cohen, L B.; Lloyd, Casasola, Stager/ 1998 Developmental Psychology. Acquisition of word-object associations by 14-month-old infants. 34(6)
The following experiments were designed to determine the age at which infants can first readily learn word-object pairings with only minimal exposure and without social or contextual support. Infants were habituated to 2 word-object pairings and then tested with 1 trial that maintained a familiar word-object pairing and 1 that involved a familiar word and object in a new combination.

26. Reviewing the power of language
More maternal vocalizing at 1 month
Associated with vocalizations at 8 & 24 months and with socioeconomic status
Also predicts greater adolescent intelligence
R2 = .22 for gazing and maternal vocalizations

27. Overview 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?

28. Socioeconomic status differences in language experience are associated with later child language competence and IQ
Meaningful differences in the everyday experiences of young American children. Hart & Risley (1995). Baltimore, MD: Brookes Publishing Co
Some text from summaries by Susan Brunner, Dahra Jackson, and Amy Vaughan

29. Participants
Longitudinal project from 9-10 months infant age up until 2-2 ½ years later
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”

30. Data collection
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)

31. Commonality
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.

32. 42 Families and the Differences Among Them
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-to-month, 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

33. 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

34. Language and SES (class)
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.

35. Talk that teaches talk THEY JUST TALKED THEY LISTENED
parents talked beyond what was needed to provide care
THEY LISTENED
To add information and prompt elaboration
THEY TRIED TO BE NICE
When enforcing a rule
THEY GAVE CHILDREN CHOICES
THEY TOLD CHILRESN ABOUT THINGS
Things worth noticing or remembering (Halloween)

36. Quantity of language: Nouns, adjectives, and adverbs to child

37. Being positive
Repetitions, extensions, expansions, confirmations, praise, approval over all feedback (including imperatives, criticisms, etc).

38. Relating things and events
Nouns, modifiers, and past-tense verbs divided by number of utterances per hour

39. “Can you. . . ?”
Proportion of yes/no questions over yes/no questions and imperatives

40. Responsiveness ‘Ok’ ‘I see’
% of responses not preceded by an initiation

41. How language experience is associated with later child IQ
“Parenting” = Language diversity + feedback tone + symbolic emphasis + guidance style + responsiveness
Predicts between and within SES groups

42. Language experience makes the difference

43. Implications for intervention
‘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.”

44. Is environmental influence global or specific?
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

45. 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

46. Support environmental specificity model
Vocabulary development depends on specific properties of language experience
Implies that enriching language experience can increase vocabulary development for low-SES kids

47. SES  Parenting  Child language
Hoff (2003)

48. Automated Vocal Analysis of Naturalistic Recordings from Children with Autism, Language Delay, and Typical Development Oller et al., 2010
Used a fully automated system to assess children’s vocalizations from naturalistic recordings
Predict linguistic development and differentiate between typically developing children and those with language-related disorders
Recordings collected from those with: typically developing language, language delay, autism
All-day recorder worn by children
Gangi

49. Recordings Signal processing software identified:
Consecutive child vocalizations: “speech-related child utterances” (SCUs)
These divided into “speech-related vocal islands” (SVIs) – analysis of rhythmic/syllabic articulation and voice
12 infrastructural acoustic features in 4 groupings:
Rhythm/syllabicity, low spectral tilt/high pitch control, high bandwidth/low pitch control, and duration
Presence or absence of each feature
- SVIs – high-energy periods bounded by low-energy periods – isolated salient “syllables” in SCUs
- Acoustic features chosen as developmental indicators and potential group differentiators
Gangi

50. Results
Automated acoustic modeling tracked development (predicted age for typically developing children) and differentiated groups
Primary factor: child’s control of infrastructural features of syllabification
Differentiated between children with and without a language disorder with higher accuracy than between the two language disorder groups (autism and language delay)
TD – all 12 correlations with age significant, little evidence of development in autism group; with multiple linear regression, correlation of predicted vocal developmental age with real age was much higher for TD and language-delayed than autism
strong identification of autism vs. TD; differentiated TD from combined autism and language-delay
Groups can be discriminated with a single day’s recording
Gangi

51. Gangi

52. Classification
Gangi

53. Niparko et al., 2010
Romero

54. Earlier implantation, earlier language gains
Romero

55. Receptive Language
Romero

56. Expressive Language
Romero

57. Other findings
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