Brain Plasticity
| Traditionally it is thought that age leads to a steady deterioration of brain function, but new research argues that older brains may take longer to process ever increasing amounts of knowledge, and this has often been misidentified as declining capacity. |
It is generally assumed that brain function undergoes a steady deterioration as we age, but now new research reported this week in Topics in Cognitive Science question that assumption.
The work, undertaken by Dr. Michael Ramscar of the University of Tuebingen, takes a critical look at the measures that are usually thought to show that our cognitive abilities decline across adulthood: Instead of finding evidence of decline, the team discovered instead that most standard cognitive measures, which date back to the early 20th Century, are flawed, confusing increased knowledge for declining capacity.
"Not only did we find that a researcher’s choice of test can determine whether cognitive functioning appears to decline or improve with age," Ramscar writes on his blog, "We also found that the results of the same cognitive test can suggest age-related declines or improvements, simply as a result of the context in which people are tested."
The Tuebingen study uses the same Big Data techniques that have been quietly revolutionizing our on-line experience to build computer models that simulate human performance in cognitive testing. Computers were trained as though they were humans, reading a certain amount each day, and learning new things along the way.
When the researchers let a computer “read” only so much, its performance on cognitive tests resembled that of a young adult. But if the same computer was exposed to the experiences we might encounter over a lifetime—with reading simulated over decades—its performance now looked like that of an older adult. Often it was slower, but not because its processing capacity had declined. Rather, just as it takes longer to find a missing sock as a drawer gets bigger, increased “experience” had caused the computer’s database to grow, giving it more data to process—and that processing takes time.
What does this finding mean for our understanding of our ageing minds, for example older adults’ increased difficulties with word recall? These are traditionally thought to reveal how our memory for words deteriorates with age, but Big Data adds a twist to this idea.
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Computationally, at least, the team show how the answer to this philosophical conundrum is, “no.” When Ramscar and colleagues trained their computer models on huge linguistic datasets, they found that standardized vocabulary tests, which are used to take account of the growth of knowledge in studies of ageing, massively underestimate the size of adult vocabularies.
It takes computers longer to search databases of words as their sizes grow, an unsurprising fact that may have important implication for our understanding of age-related slowdowns and decline. Because the Tuebingen team discovered that to get their computers to replicate human performance in word recognition tests across adulthood, they had to keep their capacities the same. “Forget about forgetting,” explained Tuebingen researcher Peter Hendrix, “if I wanted to get the computer to look like an older adult, I had to keep all the words it learned in memory and let them compete for attention.”
The research shows that studies of the problems older people have with recalling names suffer from a similar blind spot: These days people name their children in very different ways to their grandparents. This cultural shift toward greater name diversity has led to a massive proliferation in the number of names we give to our children, meaning the number of different names anyone learns over their lifetime has increased dramatically. The work shows how this makes locating a name in memory far harder than it has ever been before. Even for computers.
Ramscar and colleagues’ work provides more than an explanation of why, in the light of all the extra information they have to process, we might expect older brains to seem slower and more forgetful than younger brains. Their work also shows how changes in test performance that have been taken as evidence for declining cognitive abilities in fact demonstrates older adults’ greater mastery of the knowledge they have acquired.
Topics in Cognitive Science, Editors Wayne Gray and Thomas Hills suggest, “It is time we rethink what we mean by the aging mind before our false assumptions result in decisions and policies that marginalize the old or waste precious public resources to remediate problems that do not exist.”
SOURCE Wiley
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