New data published by researchers from The Ohio State University and partner institutions show hearing loss may influence infants’ visual processing abilities and subsequent cognitive development, including IQ.
Their findings bolster previous research confirming that congenital hearing loss affects many non-auditory skills, including working memory and sequence processing. Collectively, such results suggest that early interventions should address the whole child, and not just the ear.
A simple measure with significant meaning
“Visual habituation has been used for decades to measure how quickly and how well infants process visual information,” says Derek Houston, PhD, director of research at Ohio State’s Buckeye Center for Hearing and Development and the study’s senior investigator. “The premise is that infants who process information more quickly habituate more quickly. And there are correlations between habituation rate during infancy and abilities like nonverbal IQ later in childhood.”
The infants were shown a novel, colorful object several times during a testing session. The team recorded how long the infants looked at the object during each presentation, to track their “look-away rate” and measure how long it took to habituate.
“Our deaf infants took significantly longer to habituate to visual stimuli and showed a slower rate of habituation,” Dr. Houston says. “Because our experiment didn’t involve sound or require hearing, it suggests that lack of hearing affects certain aspects of cognitive function very early in life.”
Dr. Houston says it’s too early to apply their results to clinical practice, but they’ve moved a step forward in understanding deaf infants’ holistic development.
“It’s speculative, but perhaps visual information is more important for deaf infants than hearing infants,” he adds. “They may adapt to their hearing loss by processing stimuli more deeply or in more detail, which comes across as ‘slower’ habituation. Our next phase of research will likely test this hypothesis.”
Integrating research and clinical care
Other scientific projects underway include:
- Developing electrophysiologic technology that evaluates inner ear function and minimizes intracochlear damage, in real time, during pediatric and adult cochlear implant surgeries
- Understanding why some adults understand speech better than others following cochlear implantation, to better predict which patients may be at risk for poor outcomes
- Developing objective clinical tools for optimizing cochlear implant settings among children with cochlear nerve deficiency