How do babies learn the sound system of their language?

Learning Sound Categories

Since languages do not all use the same set of sounds, babies have to figure out which sounds are important in their language and where these sounds can occur in words. We're exploring whether babies can learn rules about where different sounds can occur in words. Babies hear a sequence of words in which only certain consonants occur in the beginning. After hearing these words, babies hear new words which do or do not follow the same patterns. We measure how long babies listen to each type of new word. We have found that 12 month olds can learn these complicated patterns after just two minutes of listening! Even 8-9 month olds can learn them with a little more training.

In another study we are looking at another micro-level of phonetic patterns. In English, vowels are produced with longer duration before a voiced than a voiceless consonant. When and how do children learn this phonetic pattern? An earlier study suggests that children's speech reflects the difference in vowel duration from very early on. Is this because babies begin learning this phonetic pattern before they can speak? We are testing 14 month old babies, and it seems that they are able to tell the difference between natural and unnatural phonetic patterns!

Speech Sound Discrimination

Infants under six months old are able to discriminate native and non-native consonant contrasts equally well, but as they learn the phonological systems of their native language, this ability declines.We are working on studies, with an associated lab in Paris -Laboratoire de Sciences Cognitives et Psycholinguistique, that will continue to explore whether there may be a statistical basis for the particular order in which non-native contrasts are lost.

How do babies recognize words in fluent speech?

Familiar Words

Well before they start to talk, babies are learning to recognize words in the speech around them. One of the earliest words to be recognized is their own name. Babies can recognize their own name in fluent speech by 4.5 months! In previous research we have shown that babies can use their name or the name “Mommy” to learn other words. In recent studies, we have been trying to figure out why hearing a familiar name helps babies to learn new words. Is it because they pay more attention after they hear a name they recognize? Or is it because knowing one word tells them where the next word begins?

Infant-Directed Speech

When talking to babies, many adults automatically change their speech register. This funny way of talking is known as “motherese”, or infant-directed speech. We are looking at different ways that motherese helps infants to understand and pay attention to the language they hear. We talk slowly, our voice gets raised, our intonation is exaggerated, and we almost always speak happily to babies! Researchers have long suggested that the unique acoustic characteristics of infant-directed speech might aid infants' language development. However, there has been little direct evidence supporting the claim. To this end, we investigate the possible link between mothers' speech and infants' word learning. Specifically, are infants able to use these exaggerated characteristics in infant-directed speech for word recognition? Which acoustic characteristics of infant-directed speech facilitate infants' recognition of words?

How do babies learn the rudimentary properties of grammar?

Grammatical Knowledge

By comparing children's listening preference for grammatical sentences ("The boy reads every night from a new book") to ungrammatical sentences ("The boy read every night from a new books"), we can learn about their knowledge of how words combine together, before they are speaking for themselves. Using this method with 16-24 month olds, we've found that children as young as 16 months are sensitive to the "s" on the ends of words in the speech of others, even though they often don't produce these "s" endings themselves until their 3rd year of life! By 24 months, infants recognize when nouns and verbs that they know are used incorrectly ( e.g. “The boy books every night from a new read” instead of “The boy reads every night from a new book”).

Ambicategorical Words

Words like "hug" and "walk" can be both nouns and verbs. When these words are used as nouns, their pronunciation is subtly different from when they're used as verbs. When we play many noun uses of these words to babies, they can tell noun uses and verb uses of the same words apart. This might help them learn the grammatical properties of these words, even though they're used as both nouns and verbs.

When do babies begin to distinguish terms of gender?

Do infants learn gender words differently?

From early on, infants hear certain words more than others, like “mommy”, “daddy” , and their own name. Baby girls may hear words associated with girls more often than baby boys do, and vice versa. Do infants learn these words differently depending on their own gender? We are currently testing whether very young baby girls respond differently to the words than baby boys do.

How well do bilingual babies use gendered articles?

Learning one language is an extraordinary feat for an infant. Now imagine what it must be like to acquire two languages simultaneously. Different languages not only have different sounds and words, but also different rules about how words go together. In Spanish, nouns are categorized by feminine or masculine gender. The word for 'the' in Spanish is 'la' for feminine nouns and 'el' for masculine nouns. Monolingual Spanish babies have shown that they can use gendered articles, like 'la' and 'el' to figure out what type of noun will come next. Our lab is now investigating whether bilingual babies learning Spanish and English can use gender information the same way.

How do babies integrate auditory and visual events?

Talking Faces

Where do babies look at a talking face? Adults tend to look each other in the eyes, but as infants are learning to speak themselves, it may be that they focus more on the mouth. By tracking their eye movements while watching a video of a woman talking, we are able to see what specific part of the face they are most interested in. We are also testing Japanese babies to find out if there are any cultural differences in the patterns of eye gaze among infants.

When do babies start recognizing components of emotion?

Emotional gestures and sounds

At the same time that they are learning language, infants are beginning to respond to the non-verbal emotional gestures and sounds that we make. We're interested in when and how infants begin to pick up on these emotional gestures and sounds. Our recent research shows that 6 month olds can tell the difference between two different kinds of happy emotional sounds.

Recent and Selected Publications