The study, published in Current Directions in Psychological Science, showed that even when older adults could hear words well enough to repeat them, their ability to memorize and remember these words was poorer in comparison to other individuals of the same age with good hearing.
"There are subtle effects of hearing loss on memory and cognitive function in older adults," said lead author Arthur Wingfield, Nancy Lurie Marks Professor of Neuroscience at the Volen National Center for Complex Systems at Brandeis University. "The effect of expending extra effort comprehending words means there are fewer cognitive resources for higher level comprehension."
"This extra effort in the initial stages of speech perception uses processing resources that would otherwise be available for downstream operations, such as encoding the material in memory or performing higher-level comprehension operations," explained co-authors Patricia A. Tun and Sandra L. McCoy.
A group of older adults with good hearing and a group with mild-to-moderate hearing loss participated in the study. Each participant listened to a fifteen-word list and was asked to remember only the last three words. All words were delivered at the same volume. Both groups showed excellent recall for the final word, but the hearing-loss group displayed poorer recall of the two words preceding it.
Because both groups could correctly report the final word, it was reasoned that the hearing-loss group's failure to remember the other two words was not a result of their inability to hear/correctly identify them. The authors interpret this as a demonstration of the effortfulness principle-- the increased effort required detracted from the cognitive processes of memorizing these words.
"This study is a wake-up call to anyone who works with older people, including health care professionals, to be especially sensitive to how hearing loss can affect cognitive function," said Dr. Wingfield.
He suggested that individuals who interact with older people with some hearing loss could modify how they speak by speaking clearly and pausing after clauses, or chunks of meaning, not necessarily slowing down speech dramatically.
Current Directions in Psychological Science, a journal of the American Psychological Society, presents the latest advances in theory and research in psychology. This important and timely journal contains concise reviews spanning all of scientific psychology and its applications.
The American Psychological Society represents psychologists advocating science-based research in the public's interest. www.psychologicalscience.org
Over the last 15 years Dr. Wingfield and Dr. Tun have carried out extensive programs of research, funded by National Institute on Aging, studying effects of aging on speech processing and memory for spoken language. More recently they have focused on effects of mild to moderate hearing loss, and how sensory changes interact with comprehension and memory for speech in younger and older adults.
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