Many deaf children—perhaps as many as 70 percent—are deprived of language

Photo by The Learning Center for the Deaf

The concern now among researchers like Caselli and Amy Lieberman, assistant professor of deaf studies in the BU School of Education, is what happens before school starts. Approximately 90 to 95 percent of deaf children are born to hearing parents who often don’t know sign language and therefore will likely struggle to teach it before their children enter school. Even among school-aged deaf children, estimates based on data from a 2010 survey from Gallaudet University, which specializes in deaf education, suggest that at most 40 percent of families use sign language at home. Given this data, educators in the field worry that a majority of deaf children may be deprived of language.

Naomi Caselli of Boston University School of Education Deaf Studies program researches language acquisition in deaf children
Naomi Caselli wants to understand how deaf children under five acquire language. Photo by Cydney Scott

Exposure to language from birth is essential for the development of thinking skills, according to a range of studies. Without access to language, children have a harder time in school. They also have more difficulty developing a sense of self and others. They even struggle with planning and time management. “It’s a constellation of challenges,” says Caselli.

So Caselli, Lieberman, and their collaborators are using the tools of linguistics, behavioral psychology, cognitive science, and education to understand how deaf children acquire language and, in turn, how best to teach them. “We desperately need data about this,” she says. “We are still at the beginning stages of identifying the most prevalent issues.”

Critical Moments

When Robert Hoffmeister founded the BU Deaf Studies program in 1980, ASL was on the fringes of acceptance. Students at BU could study it, but it did not count as a foreign language. “That’s the cloud we lived under for about 25 years,” says Hoffmeister, associate professor emeritus of deaf studies. “That cloud was more or less lifted by evidence-based research.”

Linguistic analyses showed that ASL is a language, not just a bunch of gestures. It uses space, coordinated handshapes and movements, facial expressions, and a unique syntax to build meaning. Together, this visual language has all the structural features found in spoken languages. It also has its own literary traditions. “We have folklore passed down from generation to generation,” says Bruce Bucci, a BU Deaf Studies instructor who is among several deaf faculty members at BU and communicated through an interpreter for this story. “There is a visual tradition and culture connected with the language.”

Acceptance of ASL as a language was a fundamental first step toward preventing language deprivation, because it validated the teaching of ASL to deaf babies and children. The developing brain responds to language no matter how it is presented, so exposure to ASL is equivalent to exposure to a spoken language. “The same brain regions and mechanisms perceive and acquire language regardless of the modality,” says Lieberman.

At most, 40 percent of families with school-aged deaf children use sign language at home

Photo by Cydney Scott

Researchers also learned that language deprivation delays the development of thinking skills. In 2007, Hoffmeister and colleagues studied deaf children’s development of “theory of mind,” the human ability to think about other people’s thoughts. They found that children exposed to sign language from birth develop theory of mind apace with hearing children. But children with delayed language exposure also had delays in theory of mind. “You need language to talk about the world,” says Hoffmeister, who hears but is a child of deaf parents. “Language was the crucial factor.”

Hoffmeister went on to develop ways to assess language acquisition in school-aged children. Now research in the Deaf Studies program is shifting the focus to younger children, from birth to age five. This age range is known as the critical period of language development. During those years, exposure to language triggers all kinds of development. Pull the trigger, and children associate words with things, ideas, and feelings. They form a sense of self and others, an understanding of time and planning, and an ability to pay attention and make connections.

On the flip side, without language exposure, children experience a cascade of deficits. “If babies don’t have stimulation with language during that critical time of development, then their cognitive development, their thinking skills, and their language development are all at stake,” says Nicole Salamy, a speech and language pathologist at Boston Children’s Hospital who is also a deaf studies instructor at BU.

Bucci puts it more directly: “If children are deprived of language, they will not thrive.”

The problem is that for deaf children, language is visual. It’s not passively absorbed as the sounds of life occur around them. “When deaf children have access to visual language, they can navigate their world right away,” Salamy says.

“If children are deprived of language, they will not thrive.”

Bruce Bucci, deaf studies instructor, Boston University

Language Barriers

Hearing parents of deaf children face all of the challenges of parenthood plus the need to learn a completely new language for communicating with their child. They also face conflicting advice from health providers, associations, and educators.

Some advocacy and professional groups counsel against introducing sign language, particularly targeting parents who want to use medical interventions such as cochlear implants. Parents are told that sign language will distract their child, or that it will take up space in the brain and not leave room for learning spoken languages.

Boston University Deaf Studies researcher Amy Lieberman studies ASL language acquisition by tracking eye movements to understand how deaf children learn and process language
Amy Lieberman tracks eye movements to study how deaf children learn and process language. Photo by Cydney Scott

These and other concerns have largely been debunked. In a recent review of research on the subject, Caselli and her colleagues, Matthew Hall from the University of Connecticut and Wyatte Hall from the University of Rochester Medical Center, show that learning ASL early supports learning a spoken language later, the same way learning one spoken language supports learning a second. “If you understand the structures of one language, you’ll be able to use and understand them in another,” she says.

There is also a notion that deaf children struggle with reading because they can’t sound out words. This connection between written language and sounds is called phonological coding. But according to research Lieberman did before she came to BU, this is also a misconception. “Many skilled deaf readers do not have access to phonological coding,” she says. “They clearly have alternate routes to reading, most likely having a foundation in sign language.”

Ultimately, there is no risk to introducing children to sign language. Research shows that the deaf child will only benefit, whether hearing and speech are introduced later or not. “You can do both,” says Caselli. “You can learn sign language and try to get spoken language.”

One of the biggest challenges for educators and researchers who want to improve deaf education is figuring out how to detect language deprivation. This would not only help researchers understand the scale of the problem but also help them guide deaf children and their parents to services that can smooth the way to introducing sign language.

90 to 95 percent of deaf children are born to hearing parents who often don’t know sign language

Photo by The Learning Center for the Deaf

A first step, being taken by Caselli, Lieberman, and Jennie Pyers, a visiting faculty member from Wellesley College, is to develop an ASL test for children under five. With new funding from the National Institute on Deafness and other Communication Disorders, part of the National Institutes of Health (NIH), they plan to work initially with deaf children who have deaf parents. “We want to sort out what vocabulary acquisition looks like under ideal conditions,” says Caselli.

ASL-LEX is an online visual database containing nearly 1,000 ASL signs. Caselli hopes it will become a repository for data on how and when children acquire sign language.
ASL-LEX is an online visual database containing nearly 1,000 ASL signs. Caselli hopes it will become a repository for data on how and when children acquire sign language.

From there, they will study deaf children with hearing parents, who likely face bigger challenges and potential delays as parents learn to sign. “Our goal is to determine where children fall behind and where they don’t, so that we can focus interventions,” she says.

To support this effort, Caselli developed an online visual lexical database for ASL called ASL-LEX. The tool, which won the People’s Choice Award (Interactive Category) in the “Vizzies” Visualization Challenge sponsored by the National Science Foundation and Popular Science, documents nearly 1,000 ASL signs, along with information about frequency of use, grammar, and hand movements. The database will also become a repository for information about milestones, such as the age at which children learn different signs. This information, in turn, can become a source for building assessment tools.


For parents of deaf children, job one—aside from learning the language itself—is getting the child’s attention. “It seems simple, but parents need to learn how to manage their child’s gaze,” says Lieberman.

Deaf babies who learn sign language from their parents learn to manage their attention by the time they reach preschool, according to earlier research by Lieberman. “They look up to see a sign and down to connect the sign to an object,” she says. “They do so in meaningful and purposeful ways.”

Bruce Bucci, Boston University School of Education Deaf Studies professor, holds his daughter Sophia (age one at the time) and teaches his daughter Isabella to sign “birthday” while celebrating her third birthday.
Bruce Bucci holds his daughter Sophia (age one at the time) and teaches his daughter Isabella to sign “birthday” while celebrating her third birthday. Photo courtesy of Bruce Bucci

Since eye movements reveal a lot about how deaf children process and learn language, Lieberman developed a set of studies using techniques that track eye movements and is continuing this research with a grant from the NIH. She and her research team, which includes both deaf and hearing researchers, are focused on deaf children as young as 18 months and up to five years to understand how and when they learn words.

The study will include both deaf children with deaf parents and deaf children with hearing parents. “We want to look at the full spectrum of deaf children, looking carefully at the quantity and quality of language exposure they’re receiving,” says Lieberman. “How do those two measures correlate with the ability to develop visual attention skills and new words?”

Not only will this research help develop milestones for detecting language deprivation, it will also help develop interventions for children who are falling behind. An outcome could be an educational program, or tips for parents that help them manage their child’s gaze. “Without looking, there’s no language,” says Lieberman.

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Getting the Word In

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Boston University moderates comments to facilitate an informed, substantive, civil conversation. Abusive, profane, self-promotional, misleading, incoherent or off-topic comments will be rejected. Moderators are staffed during regular business hours (EST) and can only accept comments written in English. Statistics or facts must include a citation or a link to the citation.

There are 22 comments on Getting the Word In

  1. I have been a Birth-21 Deaf Ed Teacher for 33 years. I am thrilled that this research is finally being done. I serve rural areas in Kansas, families with few resources and even fewer opportunities to access Deaf role models. I am eager to see and read more about your research as the information is published. Thank you for taking on this arduous task. Educators of children who are deaf/hard of hearing appreciate all you are doing!!

    1. Deaf role models are being increasingly visible now online! Many Deaf organizations are taking initiative on this. This video by NDC covers it really nicely! This was a research called “Role Models as Facilitators of Social Capital for Deaf Individuals: A Research Synthesis”

  2. Keep up the good work! My dissertation was on hearing children with deaf parents and how they learned spoken English and ASL.

  3. As the hearing parent of a successful adult deaf social worker I am interested in how CODAs acquire language. Both of my grandaughter’s parents are deaf and while we knew she was getting a lot of language through sign, her oral skills were a concern.

    1. CODA here, and the typical response I give when asked how I learned ASL is, “How did you learn English?” A child’s brain is remarkably receptive to any sort of communication and I believe my acquisition of ASL prepared me well to learn English, similar to learning any second language as the article touches on. Some aspects are different in the way I think, perhaps because ASL was my first language; I feel as though I don’t have a “voice inside my head,” but rather “signs in my head,” and I am an extremely visual learner. The CODA experience varies from person to person; some need speech therapy while others do not. Hope this clarifies some!

      1. I agree with CK. It is no different than a child in one country being raised in a home where the parents speak a language of another country. I am a product of this as are my children. Being US born with French-ONLY speaking parents, believe me when I say that learning English was NOT a problem! Keeping my French was! Why people think it is a concern baffles me.

  4. No question our son, now a college student, benefitted from early sign language. However, to teach him a language my husband and I did not know ourselves was no easy matter. When we learned he was deaf, the audiologist said it would be “Fun! Like the whole family learning Polish!” Well, knowing a couple of Slavic languages, Polish would have been a piece of cake. Sign was another matter. Learning it on our own in bits and pieces from classes, informal gatherings, and videos, we always felt we were falling short. Learning nouns and verbs was easy, but the more abstract concepts: difficult! Our own parents (his grandparents) did not make much headway in learning to sign to our son, so we were his interpreters even with close family. Do I have any regrets? Not about learning to sign and teaching it to him, I do regret slightly that he did not get a cochlear implant sooner. Though fully caught up to typical peers by age 7, it took some effort, and would have been easier and he would have had more contact with more people — the world! — sooner. Whatever you do, please don’t underestimate how much effort it takes parents to become fluent in ASL or even signed English when you are working and raising children. But thank you for underscoring the importance of LANGUAGE.

  5. Congratulations to my colleagues in Deaf Studies “one floor below” at 621 Comm Ave. and their continued important work. The only thing that did not come across in this piece is the warmth and friendliness of Bruce Bucci who lights up a room.

  6. What about the numerous deaf people who went through your university without language deprivation. I entered BU in 2000 and graduated in 2006, all without using a ASL interpreter, am I language deprived? It is insulting to imply I’m Language deficient by my own university.

    1. I am not trying to get in an argument with you but that is not what I hear this article saying. The article speaks about the deaf person who by circumstances beyond their control was unable to acquire any language, either signed or spoken.
      And clearly you are not language deprived if you were able to read the article and form an opinion (wrong as it is).

  7. This is excellent! Please let us at Aspen Camp of the Deaf & Hard of Hearing know if we can support this in any way. We’ll love to see research supporting growth in Deaf* children.

  8. Similar studies in hard-of-hearing language acquisition would be similarly beneficial. Though I have severe hearing deficiency, no speech capability until age 5, and speech therapy for another 10 years I was mainstreamed. ASL was never offered as an option. I learned to cope long before hearing aid technology developed enough to help me. We could do a lot more to help HoH kids today with some of these lessons learned.

  9. Wow, I knew information about the Deaf community is not widely known among parents or communities, but reading these details of where children can lose a language barrier is disappointingly unfortunate. At the time I discovered this article I am in the motion to start a club at my high school for American Sign Language. After reading, this article has sparked new ideas and research on what it really means to understand, not just learn ASL, especially for proper communication. I’ll definitely be following up on studies of this topic.

  10. I am looking for a reference portion for this article, however, I don’t see one. Among others, I would like to read the “estimates based on data from a 2010 survey from Gallaudet University” more in depth, however, the link provided directs to their website. Can anyone help?

  11. I stumbled upon this article. It was a lovely surprise since I know your father Ray Kenney. I can not imagine how painful those experiences were for him. It is truly amazing that he made such a good life for himself in spite of his past.

    On a different note, I would like to know how many words a deaf child learns by ages and compared that with hearing children. I tried to google and search for this comparison but to no avail. I just read a hearing child has heard over 4 million words in the first 4 years of their life. I am pretty sure many of us did not make it past a million, not even a thousand words in the first 4 years. I was 5 when I learned my first word.

  12. I have a cousin who have been deaf and non-verbal since she was a baby but never really got formal sign language or lip reading. She’s now in her 60’s and going blind in one of her eyes. I was wondering if there’s any type of program that can assist her to have a fulfilled what’s left of her life, she appears to be very depressed. Help needed if possible?

    A Very Concerned Cousin

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