Lecture 5 - Early Language Development Flashcards
Who investigated speech processing before birth
De Casper and Spence 1986
Outline the method of De Casper and Spencer 1986
12 pregnant women read passage from the Cat in the Hat. Chosen because regular rhyme
2/3 days after birth babies tested recognition sucking response
Played either recording cat in the hat or another unfamiliar passage
Outline the results of De Casper and Spencer 1986
Babies altered sucking pattern to hear familiar passage but not unfamiliar
Occurred irrespective whether mother or unfamiliar person reading
Recognising prosody - intonation, rhythm, stress
Babies are actively processing speech before birth
Who investigated speech recognition in Utero
De Casper, Lecanuet and Busnel 1994
Outline De Casper, Lecanuet and Busnel 1994 study on speech recognition in Utero
Changes in foetal heart rate.
35th week pregnancy recited one of two nursery rhymes.
Tested end 4 weeks by playing recording both rhythms using speakers close mothers abdomen.
Foetal HR decreased significantly to familiar rhyme only = due rhythm
Who investigated preference for familiar language
Mehler, Jusczyk, Dehaene-Lambertz et al 1988
Outline Mehler, Jusczyk, Dehaene-Lambertz et al 1988 study on preference for familiar language
4-day-old French babies presented samples French and Russian
Preferred French.
Sensitive to prosodic info - rhythm and intonation
Who investigated telling languages apart
Christophe and Morton 1998
Outline Christophe and Morton 1998 study on Telling Languages apart
Presented 2-month-old babies with 2 different language comparisons
English vs Japenese - different prosody
English vs Dutch
Sucking decreased = habituation. Only change sucking went from English to Japenese.
Tell difference between English and Japenese.
Prosody to distinguish
Why is it useful for infants in bilingual environments to distinguish languages
Ability understand different rules, stress patterns for different languages, work out patterns in language
What are Phonemes
Smallest sound unit distinguish between 1 meaning and another
e.g. b and p
Why is it crucial to tell apart different phonemes
Understand different meanings and differentiate different words and be able to relate them to things in world
Why is it crucial to perceive different variations of same phoneme
Allows flexibility and not be confused between irrelevant differences
Outline categorical perceptions of phonemes
Phoneme boundaries - where physical parameter changes perception one phoneme to another
20 ms difference across phoneme boundary easy distinguish.
20 ms difference within phoneme category hard distinguish
Outline High Amplitude Sucking (HAS) Paradigm
Test infants discrimination speech sounds.
Habituation/bored decline in sucking rate.
Introduce novel sound and notice difference sucking increase.
Outline Eimas et al 1971 study using High Amplitude Sucking Paradigm to look at infants categorical perception of speech
Phase 1: 1-4 months presented single sound /pa/. Increased sucking, then reduces to baseline
Phase 2: habituated. New similar sound played. Half heard different phoneme. Half heard variant same phoneme
Outline results of Eimas et al 1971 results
Heard different phoneme e.g. ba increased sucking rate
Like adults perceiving different categories of sound.
Cannot distinguish within categories
Is early discrimination speech sounds unique to humans?
NO!
Kuhl and Miller 1975 -
Macaques, Chinchillas and Quail do it
Phonetic Discrimination in Native and Foreign Languages
Newborns potential make phonetic discrimination
Adults do not.
Often unable hear phonetic distinctions occur other languages but not their own
e.g. Japenese do not use ‘L’ or ‘R’ = difficulty name Lara
Outline Conditioned Headturn Paradigm
Trained whenever change stimulus electric toy lit up and activated
Infants trained look toy when hear change
Target items played, observer (cannot hear) judge whether infant heard stimulus change by infants actions
Outline developmental change study - Werker and Tees 1984
Compared babies from language communities where phonemes differed. English vs Hindi. Da vs Da
Outline developmental change study - Werker and Tees 1984 Results
6-8 months tell difference
10-12 months could not tell difference
6 months universal listener
10 months stop being universal listeners
Why does developmental loss of knowledge occur? explain findings of Werker and Tees
Experience dependent
Good thing - more efficient tune into language you actually acquire. Do not need to be sensitive to all contrasts = not all relevant
Outline Kuhl et al 2006 study on effects of age and language experience: facilitation for native and decline for non-native discrimination
Japanese vs English. Discriminating r and l
10-12 months Japanese infants decline, American infants improve. Get better own language.
Outline Kuhl 2004 Neural Commitment Model
Neural tissue response becomes committed to particular contrast in own language.
Any contrasts don’t hear are not strengthened and we lose them
Outline Kuhl et al 2003 experience foreign language can reverse decline in non-native speech production
10-12 months Mandarin an English infants.
1/2 exposed English. 1/2 exposed Mandarin
American perform just as well as Chinese when exposed Mandarin
Experience dependent
Importance live interaction.
Outline Perceptual Narrowing in Infancy
Developmental loss of knowledge
Face processing - 3 month olds discriminate faces no matter ethnic group. 9 months only discriminate own ethnic groups. Own-race effect
Adults and 9 month olds discriminate between human faces. 6 month old good discriminating between human and monkeys faces
Outline Speech Segmentation
How babies tell where 1 word ends and next begins
Outline Jusczyk and Aslin 1995 study on infants ability extract words from fluent speech
Familiarised 7.5month infants repetitions of sentences. Contain 2 target words. Tested on target and novel individual words. Shown words isolation later and asked if recognise them?
Outline Jusczyk and Aslin 1995 study on infants ability extract words from fluent speech Results?
Show difference in response to words that had been embedded in familiarisation sentences
7.5 months some ability detect word when they occur in fluent speech contexts
Outline Preferential Listening Paradigm
Infants sit on caregivers lap in test booth
Each trial, one side lights flash, when infant orients to light, sounds come from that speaker.
Experimenter records how long infant looks at source of sounds as measure infants preference
AKA Headturn Preference Paradigm
How can babies tell where one word ends and next begins
Helped by infant directed speech
- higher pitch, more exaggerated intonation contours
- shorter utterances
- longer pauses
- simplified sentence structure
Outline Thiessen, Hill and Saffran 2005 study on the effect of infant-directed speech
Preference speaker using infant-directed speech.
8month olds listening to words and part words
Outline Thiessen, Hill and Saffran 2005 study on the effect of infant-directed speech Results
Easier tell apart words from part-words when listened infant-directed speech. Showed surprise when listening part-words later on.
No difference in adult directed speech - did not cement understanding
Infant directed speech a facilitator
Outline issues of effect of infant-directed speech
Familiarity preference. Infants prefer familiarity. Result complexity prefer familiarity
How can babies tell where one word ends and next begins?
Implicit discovery of cues in language input e.g.
use prosodic cues e.g. syllable stress
attend to transitional probabilities
Outline Syllable Stress
Prosodic cue to word boundary
English language puts stress in first half of words. Cue for new words
Jusczyk, Cutler and Redanz 1993 study on Infants sensitivity to syllable stress
6 months no preference.
9 months spent longer listening to strong-weak lists. Prefer words conformed to their language.
Does not confirm learning cemented
Outline statistical learning of transitional probabilities
Probability 1 syllable following another
Certain consequences syllables occur more often than others
More commonly occurring sequences likely to be words
Outline Saffran et al 1996 and Johnson and Jusczyk 2001 study number 1 into Transitional Probabilities
‘Pretty Baby’
Probability ‘ty’ following ‘pre’ high as pretty is a word.
Probability ‘ty’ and ‘ba’ following unlikely as not word. Transitional probability lower.
Outline Saffran et al 1996 and Johnson and Jusczyk 2001 study number 2 into Transitional Probabilities
Transitional probabilities in detection of word boundaries by 8 months
Invented words taking 12 syllables and combining them into 4 sequences
Presented different orders = affect probability
Outline Saffran et al 1996 and Johnson and Jusczyk 2001 study number 2 into Transitional Probabilities RESULTS
Transitional probabilities be used to distinguish ‘words’ from other syllable sequences
Probabilities higher between syllables and within words. Lower across word boundaries
Outline Saffran et al 1996 and Johnson and Jusczyk 2001 TEST STUDY into Transitional Probabilities
Infants presented 4 words. Then heard part words where syllables from 2 of words were recombined form new word
Showed part-words surprising. Novelty preference.
Discriminate between full and part words. Process and understand difference
Implications of Saffran et al 1996 and Johnson and Jusczyk 2001 study
8months able segment continuous stream speech based on stat cues alone
Bias selectively attend to certain properties in acoustic signal
What does Saffran, Werker and Werker 2006 state
Absence of external guidelines, our perceptual systems use auditory environment for our development of communication.
All occurs during 1st postnatal year
What is a word
Comprehension
Production .
Outline Comprehension
Consistent, specific response. Must be word rather nonverbal. Identify word from speech stream. Remember word to recognise. Link word with consistent event
Outline Production
Consistent and specific context. Identify word from speech stream. Remember word so recognise. Link word with consistent event. Repeat sound of word. Say word in appropriate context.
How to measure Comprehension
- Lab - ask infants choose named object from array. Preferential looking paradigm
- Home observations/Video recordings
- Parental Reports - Communicative Development Inventory - CDI. What words child uses and understands
Outline Tincoff and Jusczyk 1999 study on early word comprehension for socially salient words
6 months. Hear recordings voice saying mummy or daddy with 2 monitors.
Infants looked more video matching word heard. Intermodal matching.
6-9months also comprehend words associated with common foods and body parts.
Outline Fernald et al 1998 study on Time course of infant word recognition
Hear target word and eye-tracked.
Look efficiently towards target.
Infants rapidly look named target. Dramatic gains 2nd year.
24 months gaze shifts before offset of word
Outline development of comprehension
Understand 1st words 6-8months
Still remember after 1 instance novel object. Through elimination understand context and select novel word.
Understanding increases slowly then spurts
16months - 70-270 words
Fast mapping - ability form quick and rough meanings
