Growing up Bilingual:One System or Two?

Language differentiation and speech perception in infancy

Extending the models to Phonology• ULS (Unitary Language System)

– A common, undifferentiated storage system for all languages (Volterra & Taeschner)

– In Phonology, Flege (1987) suggests a single system with category boundaries influenced by each language

• DLS (Differentiated Language Systems)– Language systems differentiated from the beginning

(Genessee)– In phonology, Grosjean (1997). One phonology for each

language.

• One language dominant – Research with adult bilinguals showing faster phonetic

perception of L1 contrasts (Sebastian-Galles, et. al).

Organization of the Lecture

• Examining the Language Differentiation hypothesis with research on language discrimination

• Examining the Language Differentiation hypothesis with research on phonetic perception

Language Discrimination

• At birth, monolingual infants prefer native over non-native continuous speech (Moon, et. al, 1994) & can discriminate the filtered speech of rhythmically distinct languages (Mehler, et .al., 1988; Nazzi, et. al., 1998)

• By 4-5 months they not only discriminate rhythmically distinct languages, but can discriminate their own language from rhythmically similar languages, including dialectal variations of the same language (Nazzi, et. al., 2000; Ramus, et. al., 2000)

Extending to Bilinguals

• Bosch & Sebastian-Galles (1997) tested Monolingual Spanish and Monolingual Catalan infants on their ability to discriminate their native language from the unfamiliar one

• Interesting because both from the same rhythmical class

• Still some differences (more vowel reduction in Catalan)

The Orientation Latency Procedure

Picture of a woman’s face over each loud speaker.

Monolingual 4-month infants orient faster to native language

Bosch & Sebastian-Galles, Cognition, 1997

Bilingual infants orient more SLOWLY to one of their native languages over an

unfamiliar language

Bilingual infants show no difference in orientation latency

to either of their languages

Summary• Infants of 4 months can discriminate their language

from a rhythmically similar language, and show this by orienting faster to the native language

• Spanish-Catalan bilingual infants aged 4-5 months discriminate both of their native languages from an unfamiliar language.

• But, they show this discrimination of native vs. unfamiliar language by responding slower to the native language, the opposite pattern as monoliguals

• This suggests different organization for speech processing even at this early age

• No evidence in the orientation latency procedure that bilinguals can discriminate their two languages

Implications

• On the basis of the Bosch & Sebastian-Galles 1997 work, would suggest that bilinguals might be listening to language differently from monolinguals

• But no evidence of differentiation of their two language

Can Bilingual Infants discriminate their two languages?• Lack of discrimination of the two

languages, particularly when they are discriminable by monolinguals, is supportive of the ULS

• B & SG decided to use a more appropriate task to see if bilinguals can discriminate

• Used the HTPP, with a familiarization phase

Procedure: Famliarization Phase

• First familiarized infants to sentences from one of their languages

• Present a flashing light at the centre• Once the infant looked, the image disappeared, and a

slightly different image appeared on the R or L screen• After the infant looked toward that, sentence

presentation began and lasted 28 sec or until the infant looked away

• Required the infants to accumulate 2 minutes of sustained attention to the sentences (1 min to each)

Procedure: Test Phase

• New sentences

• Half in familiar language, half in the other language

• Same procedure as before

• Did the infants choose to look/listen longer to the sentences in the new language?

Sequence of Experiments

• 1st wanted to make sure the results from the Orientation Latency procedure would replicate with the Familairization/Switch task

• So first tested monolingual Spanish and Catalan infants on their ability to discriminate their native language from the other

Familiarization/Switch: Monolingual 4-monthers discriminate Spanish vs. Catalan

Bosch, et. al., 2001:

Control Study• Worried that recovery in Study 1 could have been

due to the fact that the sentences were new (although seems that was controlled for in the last experiment as well)

• And to ensure that there wasn’t just spontaneous recovery

• Tested infants with only materials from one language

• Familiarized to one set of sentences from one language, and then tested them with a new set from the same language

Control Experiment rules out simple recovery to new sentences

Can Bilinguals discriminate their two languages?

• Finally ready to conduct the key experiment

• Familiarized bilinguals to sentences in one language

• Tested on new sentences from that language vs. new sentences from the other language

Bilingual 4 monthers DO discriminate their two languages!

Implications

• These results provide very strong evidence for the DLS

• If bilingual infants as young as 2 months can discriminate their two languages, hard to argue for a ULS

• How about even earlier?

Procedure:High

Amplitude Sucking (HAS)

Werker & Burns, in prep.

Design

• Used alternating (Cowan) version of HAS procedure, but as a test of preference

• Baseline minute to set HA suck value• Presentation of speech contingent on HA suck• Collected 10 minutes of sucking, 5 minutes for

Tagalog and 5 minutes for English, with the languages alternating by minute

• Order counterbalanced• Preference DV: Do infants select to listen, i.e.

deliver more HA sucks to Tagalog or to English?

Mean # HA Sucks per Minute to English vs. Tagalog

0

510

15

20

2530

35

40

Tag-Eng Eng Only

English

Tagalog

Preliminary Conclusions: Tag/Eng Preference Study

• English infants do show a preference for English over Tagalog

• BFLA Tag/Eng newborns do NOT prefer one of their languages over the other

• Instead, they choose to listen equally to both Tagalog and English, and do so significantly more than the English babies listen to Tagalog

• This suggests that both languages are equally dominant at birth in the BFLA infant

Unanswered questions & future research

• Do BFLA infants differentiate their two languages, or is there initially one undifferentiated language space?– To test, need to see if BFLA newborns can

discriminate their two first languages

• Do BFLA infants encode enough detail about language to prefer a familiar language over an unfamliar one?– To test, need to see if BFLA newborns will show

a preference for one of their native languages over an unfamiliar language

Part II:Consonant Discrimination in BFLA

Infants (with Tracey Burns)

• In previous work we have shown there to be a reorganization in consonant discrimination in the first year of life

• Look at voicing, in a BFLA population and compare to French-only and English-only groups

Age changes in non-native discrimination

(Werker & Tees, 1984)

0

10

20

30

40

50

60

70

80

90

100

Eng.6-8 months Eng.8-10 months Eng10-12 months Hin.10-12months

Hindi Ta/ta

Salish ki/qi

Vowel Perception in Bilinguals

• Bosch & Sebastian-Galles (2003) tested Catalan and Spanish-Catalan bilingual infants on their ability to discriminate the Catalan only /e/-/E/ contrast

• At 4 months, both groups discriminated• At 8 months, only the Catalan infants did• By 12 months, both groups discriminated again• Does the data at 8 months indicate confusion

(ULS) or language dominance?• DLS by 12 months

Extensions to consonants• Test monolingual and bilingual infants on their

ability to discriminate a b-p difference that is instantiated differently in each of their languages

• Do they confuse all three sounds? (ULS)

• Do they choose the category distinction for one of their languages (language dominance)

• Or do they use all three categories and maintain both boundaries (DLS)

VOT in French & English

• English has two categories of VOT, short lag, and long lag with aspiration

• French, also has two categories of VOT, but they are long lead and short lag

• -------1------------------1------------------1--------- Fr. /ba/ Fr./pa/-Eng /ba/ Eng /pa/

Design

• -------1------------------1------------------1--------- Fr. /ba/ Fr./pa/-Eng /ba/ Eng /pa/

• Habit infants to middle stimulus, test on both others with order counterbalanced

• Test English, French, and Fren/Eng BFLA infants

Procedure

– Language exposure assessed using an adapted version of the questionnaire developed by Bosch and Sebastián-Gallés (1997)

– Infants tested in a visual habituation procedure

– Auditory stimuli presented with a checkboard display

– Pre and post tests

Visual Habituation Procedure

Results: 6-8 Month Olds

3

4

5

6

7

English Bilingual

Habituation

/ba/

/pha/

Loo

king

Tim

e (s

econ

ds)

Results: 6–8 Month Olds

• Both groups of infants dishabituate to [ba] but not significantly to [pha]

• 6 – 8 month olds show the same pattern of response regardless of home language environment

Experiment 2

Stimuli: • same as Experiment 1

Procedure:•same as Experiment 1

Participants:•10–12 month old infants being raised in monolingual English or bilingual English/French households

Results: 10-12 Month Olds

3

4

5

6

7

English Bilingual

Habituation

/ba/

/pha/

Loo

king

Tim

e (s

econ

ds)

Results: 10–12 Month Olds• Infants being raised in English speaking homes

dishabituate to [pha] but not to [ba]– This is the pattern expected given their native boundary and

previous research (Werker and Tees, 1984)

• Infants being raised in English/French homes do not show a significant change in looking times to either of the two test stimuli– Data are not uniform and suggest within-group differences

• These results suggest that the timecourse, and possibly nature, of bilingual phonetic representation is distinctly different than that of monolinguals

Experiment 3

Stimuli: • same

Procedure:•same

Participants:•14-21 month old infants being raised in monolingual English, monolingual French, or bilingual English/French households

Results: 14+ Month Olds

3

4

5

6

7

8

9

English French Bilingual

Habituation

/ba/

/pha/

Loo

king

Tim

e (s

econ

ds)

Results: 14+ Month Olds• Infants being raised in monolingual homes dishabituate to

stimuli that cross the category boundary in their native language

• Infants being raised in bilingual homes do not dishabituate to either stimuli– Bilingual data are not normally distributed: some infants appear

to be responding as monolinguals, while others dishabituate equally to both stimuli

– Age does not predict pattern of response

• Suggest that it is not the timecourse that differs but rather the nature of the representation for those infants dishabituating to both stimuli

Conclusions

–6 month olds separate the stimuli into two discrete phonetic categories

•Category boundary is the same regardless of language input

–10 month olds from monolingual homes place the category boundary in the appropriate location for their native language–10 month olds from bilingual homes do not appear to categorize the stimuli

•This suggests that the timecourse, and possibly the nature, of bilingual phonetic representation is distinctly different than that of monolinguals

Conclusions

•14+ month olds from monolingual homes place the category boundary in the appropriate location for their native language

•14+ month olds from bilingual homes appear to divide into two groups:

–Infants who categorize the stimuli as monolinguals in one of their two languages;–Infants who maintain both English and French category boundaries equally

• This suggests that for some bilinguals, it is the nature, not the developmental time course, of phonetic representation that is distinctly different than that of monolinguals

Bilingual Infants Only

3

4

5

6

7

English Bilingual

Habituation

/ba/

/pha/

Theoretical Implications

• Is it language mixing at 10-12 months for bilinguals? Maybe

• But by 14+ months there are 3 distinct patterns

• Some infants show language dominance

• Others show two differentiated systems

• No evidence of language mixing

Conclusions

• Taken together, these studies provide pretty convincing support against the ULS hypothesis

• There is little evidence of sustained language mixing

• Stronger evidence for either DLS or one dominant language