A Look at How the Brain Processes Language Patterns
Originally posted on Education Week's Inside School Research blog
By Sarah D. Sparks
Remember the famous 30 million word gap in language exposure between the children of professional families and those on welfare, and all its attendant problems in reading and attention? How could educators make up for the gap for a child with no exposure to language at all in the first year or two of life?
That's the potential gap facing more than 1 in 500 children in the United States born each year deaf or hard of hearing if their parents do not sign to them, according to Gallaudet University's Visual Language and Visual Learning Center, or VL2. The center, one of the National Science Foundation's Science of Learning Centers, launched its first "knowledge festival" on Monday night to bring together researchers working on ways to understand and build language development across multiple languages, including English, Chinese, and American Sign Language.
New neurological and longitudinal behavioral studies presented at the forum suggest visual and spoken languages are biologically equal in the brain, and early exposure can help support each other in students with deafness and normal hearing alike.
For example, Clifton Langdon, assistant professor and assistant director of the Brain and Language Laboratory for Neuroimaging, said they have found infants' brains are most sensitive to sign language syllables that happen at about 1.5 hertz per second, roughly on par with the 1.5 syllables per second frequency that infants can parse out spoken language. "That tells us the brain is not looking for particular signs or symbols of speech, but processing underlying patterns of language," Langdon said. Early exposure to this "rhythmic patterning" allows infants to begin to process language, he said. [CORRECTION: Langdon clarified the process of infants processing sound and visual syllables.]
Need for Visual, Spoken Language Exposure
Hearing loss is the most common congenital sensory problem in the country, and the National Academy of Pediatrics estimates that 98 percent of newborns receive a hearing test. But only about 1 in 4 with hearing loss are properly diagnosed and given services before they are 6 months old.
Children with normal hearing in even those in the most disadvantaged homes still were exposed to about 15 million words by age 3. But the overwhelming majority of children with hearing loss are born to hearing parents who do not sign and most do not begin to receive interventions until well over 1 year old, said Laura-Ann Petitto, scientific director and co-principal investigator of VL2. Even those who receive a cochlear implant generally are 18 months old or more before they begin to regularly hear and develop their first spoken words, because the device can take several months to fine-tune.
"Brain systems are on different maturation timetables, and one of the most unforgiving is the system for language development," Petitto said. "It peaks at age 3 ... and if the child doesn't experience exposure to the fundamental patterns of language in early life—6 to 10 months old—you are putting the child at severe risk" of major language, reading, and even math delays later on.
In a three-year longitudinal study of 3- to 5-year-old children who were deaf or hard of hearing across 20 states, VL2 co-principal investigator Thomas Allen found proficiency in ASL or fingerspelling both strongly predicted young students' proficiency in English—"Those who master one typically master the other," Allen said.
Further, young children with hearing loss met developmental milestones in signed languages in the same time periods as hearing children did on spoken languages: "fingerbabbling" at age 3 to 6 months, for example; using their simple sentences between age 1 and 2; and becoming proficient in signing by around age 3. Children with hearing loss who grew up in homes with significant signing and fingerspelling on average met those developmental benchmarks faster than those who grew up with no early signing. Their letter-word recognition abilities grew faster, too.
A few states have started to take visual languages into account when measuring early literacy. California will begin to require districts to include visual language ability when assessing their deaf students' literacy, and a similar bill in Kansas is awaiting the governor's signature.
Designing Literacy Supports for Vision and Speech
The Gallaudet researchers are developing new ways to use visual and spoken languages to support each other. For example, VL2's Motion Light Lab is developing a series of storybook apps (It has released five so far.) that allow children to read along with written text and a visual signer, and click on individual words to learn sign, written, and spoken vocabulary.
Melissa Malzkuhn, director of the Motion Light Lab, said teachers and parents can also download the tool used to generate the storybook apps to write and sign their own stories for children.
The group is also working to create nursery rhymes in sign language via computer-animated avatars. "Those amazing rhythmic patterns are sometimes lost in the translation to ASL from English," Malzkuhn said. "We're trying to recreate those patterns in ASL."
Photos: Top: Petitto, left, and Langdon cheer in American Sign Language during a presentation Monday on research breakthroughs on language development in children who are deaf and hard of hearing. Source: Sarah D. Sparks
Bottom: Young students who are deaf or hard of hearing can read along with "The Little Airplane That Could," a story told in both written type, spoken English, and American Sign Language, via an app developed by Gallaudet University researchers.
Video: An excerpt from one of the lab's motion-capture projects allows students to follow along with a nursery rhyme performed in ASL. Source: Gallaudet University