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 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], [kep ɔ d]/[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], [kep ɔ d]/[tep ɔ d].

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], [kep ɔ d]/[ket ɔ d].

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]/[d ɛ m].  Test trial  [duk]/[d ɔ k], [pize]/[pyze], [kep ɔ d]/[køp ɔ d].

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]/[d ɔ m].  Test trial  [duk]/[dœk], [pize]/[paze], [kep ɔ d]/[kup ɔ d].

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.