Post on 20-Jun-2018
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The emergence of linguistic knowledge in infant speech perception
When, why and how to build a holistic view
Alex CristiaLSCP, CNRS
Vowels (between 2 and 14)Consonants (between 6 and 122)
Figures from the World Atlas of Language Structure
Few (2-4)Many (7-14)
Few (6-14)Many (34-122)
Infant & adult-directed speech (IDS-ADS)
These two registers differ in most cultures (Lieven, 1994)
Infants attend preferentially to IDS (meta-analysis in Dunst et al., 2011)
Acoustic characteristics that distinguish IDS from ADS similar across languages/cultures → functional pressures (Ferguson, 1964)
Why is IDS different from ADS?
Attributed to (at least) 2 possible goals1. Engage attention, modulate arousal, and express
affection → IDS ≈ happy speechFernald (1990); Kaplan et al. (2002); Uther et al. (2007)
… Higher absolute pitch & expanded pitch range (Scherer, 2003;(Ohala, 1983)
… Smiling → shorter vocal tract and tenser vocal configuration – affects some vowels more than others (Tartter, 1980)
Why is IDS different from ADS?
Attributed to (at least) 2 possible goals1. Engage attention, modulate arousal, and express
affection → IDS ≈ happy speech
2. Provide “good” linguistic material to facilitate language acquisition → IDS ≈ hyperspeech
Fernald (2000); Kuhl et al. (1997); Sundberg (2001)
Clear ADS: Language-specific expansion along identifying acoustic dimensions (e.g., Andruski, 2006, Kang & Guion, 2009)
Note that prosody also affected: slower speech rates & sometimes higher pitch and larger pitch ranges (Bradlow et al., 2003; Picheny et al., 1985; Smiljianic & Bradlow, 2005))
Why is IDS different from ADS?
Attributed to (at least) 2 possible goals1. Engage attention, modulate arousal, and express
affection → IDS ≈ happy speech
2. Provide “good” linguistic material to facilitate language acquisition → IDS ≈ hyperspeech
Caregivers enhance phonologically/lexically distinctive dimensions
→ Phonemic distinctions will be stretched→ Allophonic distinctions will not
• Moms asked to talk about a set of objectsFirst to infant alone; then to experimenter &
confederate– 28 American English moms of 4-month-olds– 18 American English moms of 11-month-olds
• Objects carefully chosen to elicit tense/lax, nasal/oral, and point vowels in controlled lexical & phonotactic environments– Similar vowels (8 words w/ each vowel) with
matched preceding and following Cs and similar word frequency• Tense/lax: ε/e (pesto/basil), ɪ,i (picnic/peekaboo) • Oral/nasal: æ~/æ (dancer/tassle), ɛ/̃ε/ (tender/teddy)• Cs: (b,p,d,t,k,g)V(s,ʃ,b,p,d,t,k,)
Methods
IDS does not show category enhancement
Cristia & Seidl (2013) JCLScripts etc. athttps://sites.google.com/site/acrsta/ Home/nsf_allophones_corpora
Nu
mbe
r of results
Variation evident in a systematic review
Cristia (2013), Language and Linguistics CompassAnnotated tables downloadable from sites.google.com/site/acrsta/IDS_meta-analysis
Not an isolated findingFactors
Benders (2012)McMurray et al. (in press)
Lam & Kitamura (2012)Burnham et al. (in press)
Symbolic: Presence of categories
/s/ /ʃ/
Hypothetical acoustic dimension
Distributional: modulated by distributions
of acoustic cues
/s/ /ç/ /ʂ/
/s/
Hawaiian
English
Polish
Frequency of occurrence
Cf. Ladefoged & Cho (2005)
…
/ʃɔ .. ʃa/
/ʃɔ .. ʃa/
/ʃɔ .. ʃa/
Habituation
Average of preceding 3 trials falls below 40% of longest 3 trials
/sɔ .. sa/
/ʃɔ .. ʃa/
/ʃɔ .. ʃa/
/sɔ .. sa/
Test: fixed duration (15s)Baby /s-ʃ/
discrimination
Cristià et al. 2011 JPhon
Beyond correlations: AGL
Some learning (→ meta-analysis of [un]published results with Sophie ter Schure <s.m.m.terschure@uva.nl>)
Frequency
/ç/ /ʂ/
Frequency
Exposure type 1 Exposure type 2
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1 Individual variation in natural language acquisition
Laboratory learning (strict control input)
/ç/ /ʂ/
First steps
Phonology-first
Lexicon-first
Interactive view
Rääsanen (2012)
Johnson (2004); Beckman & Edwards (2010)
Using individual variance longitudinally: Initial benchmarks
1. Is the individual variation measured meaningful?
2. Are we tapping linguistic skill
(or just general lab performance)?
A longitudinal approach: Initial benchmarks
1. Is the individual variation measured meaningful?
Can it predict vocabulary size?
Searches in scholar.google.com, Pubmed, Science Direct, and Proquest
Identified 20 articles and theses 43 effect sizes [r] (+ 8 without comparable ES) Median r within infant group Grouped into three types: speech sounds, words, prosody
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Median effect size over all studies
r=.31 [.22, .4]
Speech perception at 4-12 months explains 5-15% variance
in vocabulary size at 11-48 months
Speech sounds r=.35 [.22, .47]Words r=.28 [.14,.4]
Prosody r=.42 [.18, .61]
Cristia, Seidl, Junge, Soderstrom, & Hagoort (in press), Developmental ScienceDatabase available at sites.google.com/site/invarinf (Individual Variation in Infancy)
A longitudinal approach: Initial benchmarks
1. Is the individual variation measured meaningful?
2. Are we tapping linguistic skill
(or just lab performance)?
For now, 2 ways to answer
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1. Reuse existing data
Habituation r=.45 [.2, .65]Dishabituation r=.42 [.29, .54]
Rapid auditory processing r=.54 [.25, .74]
Overall non-linguistic infant predictors of vocabulary r=.43 [.35, .5]
Speech-speech: r=.43 [.28, .57]
Correlations within infancy Speech + non-linguistic: r=.25 [.08, .40]
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2. Direct experimental comparison
Predictions: General lab performance Cognitive demands of the task Emergent language skills
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2. Direct experimental comparison
Predictions: General lab performance Cognitive demands of the task Emergent language skills
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2. Direct experimental comparison
Predictions: General lab performance Cognitive demands of the task Emergent language skills
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2. Direct experimental comparison
Predictions: General lab performance Cognitive demands of the task Emergent language skills
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2. Direct experimental comparison
Predictions: General lab performance Cognitive demands of the task Emergent language skills
Trochees Vowels VRM
Vowels 0.30*
VRM 0.05 -0.07
A/B 0.1 -0.2 0.09
Seidl, Cristia, Wang, & French (variably rejected)
Kuhl, 1994; Kuhl et al. 2008 Curtin & Werker, 2005 : Curtin et al., 2011
Extension to current theories
PHONEME[k]
WORDFORM
generalizations
Increasing sensitivity: better measures
High replicability (+portability)
High reliability
'Intensive'- Compatible with a multivariate approach
Input, output, perception
+ state-of-the-art algorithms, e.g.SOUNDS: Supervised phone recognizer WORDS: Semi-supervised term discovery
Other problems of individual variance
Limited pool of variance:
Twin studies → heritability 25-67% (Stromswold, 2001); single factor emerges (e.g., Bornstein et al., 2012)
Conceptual ambiguity:
Precise theories (quantitative predictions)
Causality can never be demonstrated
AGL, models, animal parallels...
Summary
Multivariate approaches
Not only in vogue, but even necessary (often)
Infant studies' low SNR
Interactions may fall below sensitivity
Principled way to structure search
Models could play a key role
Face conceptual inseparability