Bosch & Sebastián-Gallés

Simultaneous Bilingualism and the Perception of a Language-Specific Vowel

Contrast in the First Year of Life

Introduction:

This research explores the behaviour of monolingual Spanish and monolingual Catalan infants, in order to analyze their perception of native-sound contrasts.

Because other research has been done on monosyllabic stimuli, this study used a more complex structure (CV1CV2).

The vowel contrast studied was /e/ and /ε/.

Hypotheses

Experiment 1: All three subgroups would perceive the vowel

contrast at 4 months of age.

Experiment 2: However, at the age of 8 months, only the

monolingual Catalan group should perceive the vowel contrast.

Experiment 1:

Subjects: 36 infants of 4 months of age were recruited

3 groups of 12 infants: Catalan monolinguals Spanish monolinguals Catalan-Spanish bilinguals

The experimenters were interested in the 2 monolingual groups.

Stimuli:

The contrastive category that is studied is the Catalan vowel contrast /e/ and /ε/ (two midfront vowels) in a CV1CV2 context.

In determining the infants’ discrimination capacities, the experimenters: placed the vowel in the first stressed syllable

of a pseudoword; used several tokens from five different females

(variability).

Stimuli (cont):

Pseudowords [‘dV.i] with V= /e/ and /ε/.

18 tokens were recorded from 5 females (native speakers of Catalan and Spanish)

Motherese style

Stimuli: (cont)

How were the stimuli chosen?

Acoustic perspective vs phonetic perspective

Formants of each token

Procedure

Head-turn preference procedure An image on the center monitor appears to capture the

infant’s attention and to have him focused.

A speech stimulus is presented to the infant from either the left or right loudspeaker.

If there is a change in the speech stimulus, the infant will turn his head towards the stimulus.

If the child turns his head on the right side, a picture will appear on the monitor (reinforcement).

(source: http://www.psych.ubc.ca/~jwlabmgr/meth_cond.html)

Procedure (cont):

1) familiarization phase based on the infants’ looking behavior; half of the infants were familiarized with [‘dei], the

other half with [‘dεi] each infant had to accumulate 2 minutes of sustained

attention

2) testing phase listening of contrastive materials; there is discrimination when there is differential

attention time (greater listening time) between similar and novel materials;

the similar materials are the tokens presented in the familiarization phase.

Familiarization phase:

Structure of a trial: Two sets of 6 tokens from the same vowel category

were presented to the infant. Up to 6 trials of 25 seconds were needed to obtain a 2

minute sustained attention.

Group 1 Group 2[‘dei] [‘dei] [‘dεi] [‘dεi][‘dei] [‘dei] [‘dεi] [‘dεi][‘dei] [‘dei] [‘dεi] [‘dεi][‘dei] [‘dei] [‘dεi] [‘dεi][‘dei] [‘dei] [‘dεi] [‘dεi][‘dei] [‘dei] [‘dεi] [‘dεi] x2 x2 x2 x2

Testing Phase:

New tokens of the same category of vowels from the familiarization phase are presented to the infant;

Contrastive tokens are presented to both groups. Infants react to those tokens by staring

Results Experiment 1:

Mean attention time:

Results Experiment 1

Hypothesis confirmed:

An infant of 4 months can discriminate the vowel contrast of /e/ and /ε/ within the first syllable of a disyllabic CVCV stimulus.

They can also normalize for talker and token variability.

This shows that at 4 months, the ambient language still has no effect on their ability to discriminate vowel contrasts.

Experiment 2

For the second experiment, Bosch and Sebastián-Gallés were interested in analyzing the impact that linguistic exposure would have on eight-month-old infants’ ability to perceive vowel contrasts.

Hypotheses:

Since these two categories are present only in Catalan, eight-month-old infants coming from Catalan-speaking families should discriminate them.

However, infants coming from Spanish-speaking families should not be able to perceive the contrast as easily since it is not present in their language.

Subjects & Stimuli:

Subjects: 8 month old infants 3 groups participated in this experiment:

Catalan monolinguals Spanish monolinguals Catalan-Spanish bilinguals

Stimuli: Same vowel contrasts (/e/ and /ε/) from

Experiment 1.

Results Experiment 2:

Mean attention time

Results Experiment 2 (cont):

The Catalan monolingual group, which is exposed to this vowel contrast in its linguistic environment, has no problem perceiving it.

On the other hand, eight-month-old infants from Spanish monolingual environment might only perceive the two vowels as being different ways of producing the same vowel.

Discussion:

The results of both experiments confirm the following predictions :

At four months, babies from both Catalan monolinguial and Spanish monolingual environments can discriminate the Catalan vowel contrast /e/-/ε/.

At eight months, only infants from the Catalan monolingual environment can perceive the contrast, showing that linguistic exposure might alter these language-general initial sensitivities.

Let’s Wrap it Up!!!

The experiments have shown with different contrasts that at the age of 4 months, infants are universal listeners.

We can also see that around 8 months of age, infants start to lose the sensitivity to discriminate languages and they become more sensitive to the contrasts in their mother tongue.