BU Today

Close Up

Baby Talk at Sargent College, May 8th, 2006

all close ups

On a recent morning in the Sargent College Infant Language Lab, the first test subject is seven-and-half-month-old Eliza. Wearing a pink dress and a bow in her hair, she smiles when the lights in the testing booth flash and a low-pitched voice calls out, “Hat, hat, hat.” She claps when a high-pitched voice says, “Bike, bike, bike.” But by the time the single words stop and the sentences that test word recognition begin — “The bike could go very fast” — Eliza is examining her shoes. A minute later, she’s rubbing her eyes and churning her legs. Eliza’s mother gives her a pacifier, but she flings it to the ground, in tears.

“Never a dull moment here,” says Leher Singh, a Sargent College assistant professor of speech, language, and hearing sciences. “That’s one of the problems with working with infants. You can’t reason with them. It’s why we need to test so many babies. You expect a little noise in your data.” A little noise, yes, and a fair amount of crying, squirming, and sleeping, too.
But despite all the commotion and easy distraction, Singh knows these babies are working intensely to learn language before they say a single word. She uses this lab to tap into the infant mind, to find out, for instance, when babies learn that the word “cup” is the same word whether Mommy or Daddy says it and whether it’s said in a happy or a neutral tone or in a high or a low pitch. Her findings could help diagnose and treat children with speech-language delays.

Singh’s work is just one of dozens of research projects at Sargent College of Health and Rehabilitation Sciences. Since its founding 125 years ago, the college has grown to an institution with 97 full- and part-time faculty and more than 1,200 students in baccalaureate, master’s, and doctoral programs. With about $6 million in federal and other funding, Sargent faculty research areas such as movement disorders, psychiatric rehabilitation, and speech disorders.

Lights, Camera . . . Words!

Like Singh’s study subjects, her field itself is quite young. Until the early 1970s, most people assumed that language learning began with a child’s first word, a moment of epiphany around age one upon which a lifetime of communication is built. Then in 1971, Brown University researchers Peter Jusczyk and Peter Eimas published a study in Science reporting that babies as young as a month old could distinguish between “ba” and “pa,” supporting the theory that people have an innate ability to perceive language. In later studies, Jusczyk showed that babies as young as seven and a half months could attach meaning to individual words. Research suggests that infants don’t usually say their first word until around age one, partly because that is when their facial muscles have developed the dexterity needed to form words.

Singh is researching when and how babies learn what variation they can ignore when learning words (loudness, for example) and what variation matters to word meaning (such as phonetic differences between words like ball and bell). Then there’s the added complication that variation that doesn’t matter at all in one language can matter a great deal in another language. For example, the meaning of English words doesn’t change if spoken in a rising or a falling tone, but the meaning of Mandarin Chinese words does. The Chinese word “ma,” for instance, can mean mother, horse, or hemp, or signify reproach, depending on how it’s spoken.

“Infants are picking up so much in that first year,” says Sarah Nestor, Singh’s lab administrator, who typically puts the babies through the word-recognition tests. “These babies are like little computers, processing all this data that’s coming in all the time.”

Nestor also recruits babies for Singh’s studies. “Some people call me a baby hunter,” she jokes.

The language lab consists of two soundproofed rooms with a pin-hole camera between them. When running an experiment, the researcher is in one room with a fish-eye view into the second room, where the baby sits, usually in a parent’s lap, facing a three-sided screen and listening to a computer-programmed series of words and sentences.

A light flashes on one side of the screen or the other, depending on which of two randomly chosen test words is being called out, with a single variable of speech. In Eliza’s case, “hat” and “bike” varied by pitch. Then sentences begin, cued by the same attention-getting lights, some containing one of the two test words and some without either, but all spoken in the same manner as one of the chosen words. For example, all of the sentences Eliza heard were spoken in a low-pitched voice just like the word “hat.” A researcher codes how long a baby looks at the light accompanying any given sentence; earlier studies have indicated that a baby will pay more attention (gaze longer at the light) when listening to sentences containing a word she recognizes.

Over the past few years, Singh has gathered data on hundreds of infants, through both lab results and other measures, such as basic cognitive tests; in infants older than one year, she uses “phonological memory” exercises that test how well infants remember made-up words, such as “nide,” “sice,” and “bome.”

She has found that most babies as young as Eliza perceive the low-pitched “bike” of the sentences as a different word from the high-pitched “bike” they learned earlier in the experiment. Taking variable pitch into account could be useful for a baby learning Mandarin Chinese, but it’s a hindrance to learning English. This type of evidence supports Singh’s belief that infants are “born into the world prepared to learn any language and then begin to focus on their own language and which contrasts are relevant.” In Singh’s longitudinal experiment, she periodically tests babies from seven and a half months to twenty-six months of age. In these tests, babies learning English begin to recognize that a word spoken in different tones is the same word by around age ten or eleven months.

Another of Singh’s experiments is a cross-cultural study of infants in English-speaking, Chinese-speaking, and bilingual households. In yet another, she tested how well babies recognize the same word voiced in a different emotion — happy or neutral. “I tried doing negative emotions,” she says. “But the babies just burst into tears. Total meltdowns. We couldn’t get through a trial.”

Ultimately, Singh hopes to discover what parts of language learning are hardwired in infants and what external factors — time spent with parents, television, siblings, playmates, or educational toys, for example — help, hinder, or make no difference in the speed of language learning.

“The idea of this is that if somebody said to you, here’s a list of all the things that could prime an infant for good language learning, what would they be? And what type of situations set up a child for language learning problems?” says Singh, who surveys parents of tested infants along these lines. “There’s a whole cottage industry of toys and props that are designed for new parents to teach their child language or to increase their child’s IQ. To what extent are these useful?”

She hopes to piece together the “normal” pattern of infant word learning in order to identify, as early as possible, children who may need extra help with language. Singh’s colleague, Adele Raade, a speech therapist and a Sargent College assistant professor of speech, language, and hearing sciences, currently works with kids between the ages of two and eight, but she spent several years working with even younger children in what’s known as early intervention.

“Sometimes you don’t really know specifically why a child is exhibiting language delay, and the treatment depends on the underlying reason,” says Raade. “It’s not like you can ask for verbal reports. So it can be a clinical challenge.”

Raade believes Singh’s work could help clinicians with these challenges. “The more sophisticated we are about knowing what typically developing children do, the earlier we can catch kids who are at risk,” she says. And the earlier treatment begins, the more likely it is that language delays can be overcome.

Singh hopes to do a study that will follow children from infancy to four or five years old, when they’re preparing to enter school. “I’d like to look at how their preparedness for literacy or for a formal education is predicted by their language learning skills in infancy,” she explains.

Nevertheless, Singh is quick to point out that there’s more to language learning than words. “I’m just looking at one aspect of language. Other people have to look at grammar, phonetics, and pragmatics [appropriate use of language],” she says, “so this is a really small piece of the pie.”

Progress isn’t always smooth, as the morning with Eliza demonstrates, but Singh is patient. “The studies sort of plod along quite slowly,” she says. “But I feel like every increment of information you get is massive, because nobody’s really looked at this before. It’s a real sense of discovery.”

 Cover photo of John Fitzgerald by Mary Collins.