Use of phonetic specificity during the acquisition of new words: Differences

between consonants and vowels.

Thiery Nazzi (2004)

By: Dominique, Jennifer, Jesse, Judith, Justine and Mélissa

Goal of Experiment

Explore the issue of the use of phonetic specificity in the process of learning new words at 20 months of age.

Experiment will be conducted on French infants.

History

Previous research has been done on 14 months old and 17-20 months old infants.

In 2001 Nazzi and Gopnik did the same experiment on 20 month olds English speaking infants.

Focus of Experiment

1. Phonetically different words. [pize] vs. [mora]

2. -A: Words differing minimally on their onset cluster. [pize] vs. [tize]-B: Non-initial consonant clusters.[pide] vs. [pige]

3. A – C: Vocalic contrasts.[pize] vs. [paze]

Hypothesis????

1) Performance would be higher with vocalic contrasts than with consonantal contrasts due to the infants great reliance of vowels during the first year of life.

2) Consonants are more important at the lexical level while vowels are more important at the prosodic and morphosyntactic level.

Experiment Method

Notwithstanding minor differences in subject groups, each experiment was carried out in a nearly identical fashion.

Triads of objects were given invented novel names, and two of the three objects carried the same name.

Prior to experimental testing, the subjects experienced an habituation period.

Experiment 1

Focus: Phonetically different words.

Subject group: Parents completed questionnaire. 12 boys & 12 girls aged 20 months old. All subjects monolingual French. Most subjects from white middle class. 4 infants failed to complete the experiment

Experiment 1

Stimuli and Procedure: 6 triads of unfamiliar objects (an extra triad

was used during the pretest). All objects were different in size, color,

shape and texture. There was an informal warm up period and

then the infants were all tested individually for about 10 minutes.

TRIAD

Experiment 1

Warm up trial [laf]/[nim]. Test trials [duk]/[zap], [pize]/[moRa],

[kepɔd]/[nylis]. Each trial was composed of an presentation

phase followed by a categorization phase.

Experiment 1

Presentation Phase: Presented the objects 3 at a time. Each object was named exactly 6 times.Categorization Phase: Infant was asked to give the experimenter the

object with the same name. Positive feedback was always present even in

the case of a wrong answer.

Experiment 1

Results: Infants were given a score of 0 or 1 when

they picked the object. Infants chose the correct object 73.6% of the

time. There is no correlation between the

vocabulary size and the categorization performance.

Experiment 2 A-B

Focus:

A-Minimal consonantal contrast on the word initial consonant.

B-Minimal consonantal contrast on non-initial consonant.

Experiment 2 A-B

Subject group: 24 boys & 24 girls aged 20-months. 4 additional infants were tested, but failed

to complete the test. Infants from white middle class, other

ethnicities were represented to a lesser extent.

Experiment 2 A-B

Stimuli and Procedure: Process and object triads were identical to

Experiment 1. Single most crucial difference was the names

used when labeling objects.

Experiment 2A

Experiment tested a minimal consonantal contrast on the word-initial consonant:

Warm-up trial [dim]/[bim]. Test trial [duk]/[guk], [pize]/[tize],

[kepɔd]/[tepɔd].

Experiment 2A

Results: Infants chose the second object with the

same name 63.2% of the time. Almost all the infants chose the correct

object on more than ½ of the test trials.

Experiement 2B

Tested a minimal consonantal contrast on a non-initial consonant

Warm-up trial [dib]/[dig]. Test trial [duk]/[dut], [pide]/[pige],

[kepɔd]/[ketɔd].

Experiment 2B

Results: Infants chose the second object with the

same name 65.3% of the time. Most of the infants chose the correct object

on more than ½ the test trials.

Experiment 2 A-B

Implications of Experimental results: 20 month-old infants are able to

simultaneously learn 2 phonetically similar words that consonants contrasting minimally in place of articulation at word initial or non-initial positions.

Confirms findings by Werker et al. (2002) that this acquisition is not language specific.

Experiment 2 A-B

Implications of experimental results: 20 month-old infants can take into account

the minimal phonetic contrasts which were tested.

These results may suggest that a consonant is less dependant on the acoustic salience at 20 months, than it seems to be at around 11 months.

Experiment 3 A-C

Subjects: 36 boys and 36 girls aged 20-months. From monolingual French-speaking families. 9 additional infants were tested, but failed to

complete the session.

Experiment 3 A-C

Stimuli and Procedure: Procedure identical to that used in the

previous experiments. Same object triads were used. Different names used to label the objects.

Experiment 3 A

Tested a minimal vocalic contrast (1 phonetic feature) on the first vowel of the words.

Warm-up trial [dim]/[dɛm]. Test trial [duk]/[dɔk], [pize]/[pyze],

[kepɔd]/[køpɔd].

Experiment 3 B

Tested a more pronounced vocalic contrast (more than 1 phonetic feature) on the first vowels of the words.

Warm-up trial [dim]/[dɔm]. Test trial [duk]/[dœk], [pize]/[paze],

[kepɔd]/[kupɔd].

Experiment 3 C

Tested an even bigger contrast: the same kind of more pronounced vocalic contrasts used in experiment 3b was used in word-final position.

Warm-up trial [dRo]/[dRy]. Test trial [da]/[di], [pize]/[pizu],

[kepRo]/[kepRi].

Experiment 3 A

Results and Discussion: The infants chose the second object with the same

name 54.9% of the time. Less than half of the infants chose the correct

object on more than half of the test trials. Infants had a mean of 114 words, the median was

62 words. No correlation between vocabulary size and

categorization performance.

Experiment 3 B

Results and Discussion: The infants chose the 2nd object with the same

name 53.8% of the time. Less than half chose the correct object on more

than half of the trials. Infants had a mean of 68 words, and a median of

54 words. No correlation between vocabulary size and

categorization performance.

Experiment 3 C

Results and Discussion: The infants chose the second object 54.2% of the

time. Less than half chose the correct object on more

than half of the trials. The infants had a mean of 95 words, and a median

of 49 words. No correlation between vocabulary size and

categorization performance.

Experiment 3 A-C

General Observations: 20 month-old infants have difficulties

learning simultaneously two words that differ only by one of their vowels.

They also don’t use all phonetic contrasts while learning new words.

General Discussion

The goal of this study was to explore 20-month-old use of phonemic specificity in the process of acquiring new words.

Name-based categorization task.

General Discussion

Recap: Experiment 1 Experiment 2 Experiment 3

General Discussion

Hypothesis 1: Performance would be higher with vocalic

contrasts than with consonantal contrasts due to the infants great reliance of vowels during the first year of life.

There is a greater reliance on consonants at the lexical level in infancy than previously thought.

General Discussion

Hypothesis 2: Consonants are more important at the lexical

level while vowels are more important at the prosodic and morphosyntactic level.

According to the results we had, hypothesis 2 was proven to be valid.

General Discussion

Conclusion: We need more evidence to strengthen this

interpretation. How? Why? Important note: This study call for more

systematic research to be conducted on the vocalic specificity of infant’s representation of word they already know.