Thierry Nazzi

Language Discrimination by Newborns: Toward an Understanding of the Role of Rhythm

Three experiments investigated the ability of French newborns to discriminate between sets of sentences in different foreign languages. The sentences were low-pass filtered to reduce segmental information while sparing prosodic information. Infants discriminated between stress-timed English and mora-timed Japanese (Experiment 1) but failed to discriminate between stress-timed English and stress-timed Dutch (Experiment 2). In Experiment 3, infants heard different combinations of sentences from English, Dutch, Spanish, and Italian. Discrimination was observed only when English and Dutch sentences were contrasted with Spanish and Italian sentences. These results suggest that newborns use prosodic and, more specifically, rhythmic information to classify utterances into broad language classes defined according to global rhythmic properties. Implications of this for the acquisition of the rhythmic properties of the native language are discussed.

Before and after the vocabulary spurt: two modes of word acquisition?

This paper focuses on early lexical development, and especially the period around 18 months known as the vocabulary spurt. We first propose that this period corresponds to a shift from an associationist to a referential lexical acquisition mechanism following the developmental coupling of specific pre-linguistic and cognitive abilities. This latter mechanism would allow the acquisition of genuine words, i.e. links between phonetically specified sound patterns and object categories. We then review the literature on early lexical acquisition by typically developing infants and infants with Down and Williams syndrome, and report some data that were recently collected on this issue. We conclude that the data so far are congruent with our proposal, but because they remain insufficient, we propose some future research that focuses on the relation between pre-linguistic and cognitive developments.

Discrimination of pitch contours by neonates

With the high-amplitude sucking procedure, newborns were presented with two lists of phonetically varied Japanese words differing in pitch contour. Discrimination of the lists was found, thus indicating that newborns are able to extract pitch contour information at the word level.

Language specific prosodic preferences during the first half year of life: Evidence from German and French infants

There is converging evidence that infants are sensitive to prosodic cues from birth onwards and use this kind of information in their earliest steps into the acquisition of words and syntactic regularities of their target language. Regarding word segmentation, it has been found that English-learning infants segment trochaic words by 7.5 months of age, and iambic words only by 10.5 months of age [Jusczyk, P. W., Houston, D. M., & Newsome, M. (1999). The beginnings of word segmentation in English-learning infants. Cognitive Psychology, 39, 159-207]. The question remains how to interpret this finding in relation to results showing that English-learning infants develop a preference for trochaic over iambic words between 6 and 9 months of age [Jusczyk, P. W., Cutler, A., & Redanz, N. (1993). Preference for the predominant stress patterns of English words. Child Development, 64, 675-687]. In the following, we report the results of four experiments using the headturn preference procedure (HPP) to explore the trochaic bias issue in German- and French-learning infants. For German, a trochaic preference was found at 6 but not at 4 months, suggesting an emergence of this preference between both ages (Experiments 1 and 2). For French, 6-month-old infants did not show a preference for either stress pattern (Experiment 3) while they were found to discriminate between the two stress patterns (Experiment 4). Our findings are the first to demonstrate that the trochaic bias is acquired by 6 months of age, is language specific and can be predicted by the rhythmic properties of the language in acquisition. We discuss the implications of this very early acquisition for our understanding of the emergence of segmentation abilities.

Differential Processing of Consonants and Vowels in Lexical Access Through Reading

Do consonants and vowels have the same importance during reading? Recently, it has been proposed that consonants play a more important role than vowels for language acquisition and adult speech processing. This proposal has started receiving developmental support from studies showing that infants are better at processing specific consonantal than vocalic information while learning new words. This proposal also received support from adult speech processing. In our study, we directly investigated the relative contributions of consonants and vowels to lexical access while reading by using a visual masked-priming lexical decision task. Test items were presented following four different primes: identity (e.g., for the word joli, joli), unrelated (vabu), consonant-related (jalu), and vowel-related (vobi). Priming was found for the identity and consonant-related conditions, but not for the vowel-related condition. These results establish the privileged role of consonants during lexical access while reading.

Better Processing of Consonantal Over Vocalic Information in Word Learning at 16 Months of Age

Previous research using the name-based categorization task has shown that 20-month-old infants can simultaneously learn 2 words that only differ by 1 consonantal feature but fail to do so when the words only differ by 1 vocalic feature. This asymmetry was taken as evidence for the proposal that consonants are more important than vowels at the lexical level. This study explores this consonant-vowel asymmetry in 16-month-old infants, using an interactive word learning task. It shows that the pattern of the 16-month-olds is the same as that of the 20-month-olds. Infants succeeded with 1-feature consonantal contrasts (either place or voicing) but were at chance level with 1-feature vocalic contrasts (either place or height). These results thus contribute to a growing body of evidence establishing, from early infancy to adulthood, that consonants and vowels have different roles in lexical acquisition and processing.

Bias for Consonantal Information over Vocalic Information in 30-Month-Olds: Cross-Linguistic Evidence from French and English.

Using a name-based categorization task, Nazzi found in 2005 that French-learning 20-month-olds can make use of one-feature consonantal contrasts between new labels but fail to do so with one-feature vocalic contrasts. This asymmetry was interpreted as developmental evidence for the proposal that consonants play a more important role than vowels at the lexical level. In the current study using the same task, we first show that by 30 months French-learning infants can make use of one-feature vocalic contrasts (e.g., /pize/-/pyze/). Second, we show that in a situation where infants must neglect either a consonantal one-feature change or a vocalic one-feature change (e.g., match a /pide/ with either a /tide/ or a /pyde/), both French- and English-learning 30-month-olds choose to neglect the vocalic change rather than the consonantal change. We argue that these results suggest that by 30 months of age, infants still give less weight to vocalic information than to consonantal information in a lexically related task even though they are able to process fine vocalic information.

Early Word Segmentation by Infants and Toddlers With Williams Syndrome

This study tested the ability of English infants and toddlers with Williams syndrome to segment, that is, to extract from fluent speech, bisyllabic nouns that had either a strong–-weak stress pattern (predominant in English), or a weak–-strong stress pattern. The testing procedure was the same for both types of words: Children were familiarized with instances of isolated nouns, and then tested on their recognition of these nouns embedded in passages. In English, typically developing infants start segmenting strong–-weak nouns by 7.5 months of age, and weak–-strong nouns by 10.5 months. Our clinical population was able to segment strong–-weak nouns, but failed, despite chronological ages above 15 months, to segment weak–-strong words. These results suggest that the development of word segmentation is seriously delayed in Williams syndrome. This deficit in early phonological processing may contribute to a fuller understanding of the late lexical onset in this population, a phenomenon that had hitherto only been explained in terms of cognitive and semantic deficits.

Morae and Syllables: Rhythmical Basis of Speech Representations in Neonates

Are neonates sensitive to the different rhythmical units that are used in different spoken languages? And do they use these units to represent and discriminate multisyllabic words? In the present study, we used the High-Amplitude Sucking procedure to test whether 3-day-old French infants discriminate lists of Japanese words. The lists of words differed either in the number of syllabic units or in the number of sub-syllabic units such as morae. In Experiment 1, infants heard bisyllabic versus trisyllabic words (e.g.: iga vs. hekiga); in Experiment 2, they were presented with bimoraic versus trimoraic bisyllabic words (e.g.: iga vs. iNga). The results corroborate those obtained by Bijeljac-Babic, Bertoncini, and Mehler (1993), providing further evidence that neonates discriminate bisyllabic from trisyllabic words. In contrast, neonates do not appear to discriminate bisyllabic words that vary in number of sub-syllabic units. It is proposed that syllables are particularly salient units during the initial stage of speech processing, irrespective of which language and rhythmical structure is heard.

Infant ability to tell voices apart rests on language experience

A visual fixation study tested whether 7-month-olds can discriminate between different talkers. The infants were first habituated to talkers producing sentences in either a familiar or unfamiliar language, then heard test sentences from previously unheard speakers, either in the language used for habituation, or in another language. When the language at test mismatched that in habituation, infants always noticed the change. When language remained constant and only talker altered, however, infants detected the change only if the language was the native tongue. Adult listeners with a different native tongue from the infants did not reproduce the discriminability patterns shown by the infants, and infants detected neither voice nor language changes in reversed speech; both these results argue against explanation of the native-language voice discrimination in terms of acoustic properties of the stimuli. The ability to identify talkers is, like many other perceptual abilities, strongly influenced by early life experience.