Hearing impaired babies are more attuned to visual cues, according to a new study led by the University of Washington's Institute for Learning & Brain Sciences (I-LABS).
The research team sought out deaf infants raised by deaf parents -- families who primarily use visual language and visual cues. Deaf infants exposed to American Sign Language demonstrated strong gaze-following behaviour -- and at a more advanced level than hearing infants. The study was published in the journal Developmental Science and stems from broader research into early learning and finds that deaf infants of deaf parents may be more attuned than hearing infants to the social and visual signals of others.
The study was funded by the National Science Foundation, the National Institute of Child Health and Human Development, the Virginia Merrill Bloedel Hearing Research Center and the I-LABS Innovative Research.
"Children adapt to the people who communicate with them," said Rechele Brooks, a research scientist at I-LABS and lead author of the study. "Whatever your social context is, you're learning from the people around you. Children thrive through interactions with other people. This work shows that children tune into social cues in their environment starting from early infancy."
While gaze following in hearing infants has been studied, the behaviour hasn't been formally examined in deaf infants.
Since fewer than 10% of deaf infants have deaf parents, the research team had to recruit deaf infants from across the country. 12 deaf infants participated in the study, along with 60 hearing infants of the same age. Both groups had natural experience with language from birth with their families -- the deaf infants with visual language (American Sign Language) and the hearing infants with spoken language.
During the study, each infant sat with a parent, facing a researcher across a table. The researcher set up the room with two objects, one on either side of the infant. Silently, the researcher then looked to one of the two objects, and a camera recorded the infant's response. Each trial was objectively "scored" based on where the infant directed their gaze. Scores showed that the deaf infants were nearly twice as likely as hearing infants to accurately follow the gaze of an adult. Younger deaf infants, between 7 and 14 months old, even more so than hearing infants.
This accelerated gaze following among deaf infants could be a result of their exposure to sign language. Deaf infants were also more apt to look back at the adult after following the adult's gaze-- a form of communication, indicating that the infant may be looking for more information from the adult. Hearing infants can learn from both what an adult looks at and what the adult verbally says about it while deaf infants must rely on visual cues.