Tuesday, January 21, 2014
Older brains slow due to greater experience, rather than cognitive decline
What happens to our cognitive abilities as we age? Traditionally it is thought that age leads to a steady deterioration of brain function, but new research in Topics in Cognitive Science argues that older brains may take longer to process ever increasing amounts of knowledge, and this has often been misidentified as declining capacity.
The study, led 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 that most standard cognitive measures are flawed, confusing increased knowledge for declining capacity.
Dr. Ramscar's team used computers, programmed to act as though they were humans, to read a certain amount each day, learning new things along the way. When the researchers let a computer 'read' a limited amount, its performance on cognitive tests resembled that of a young adult.
However, if the same computer was exposed data which represented a lifetime of experiences its performance looked like that of an older adult. Often it was slower, not because its processing capacity had declined, but because 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," said Dr. Ramscar. "Technology now allows researchers to make quantitative estimates about the number of words an adult can be expected to learn across a lifetime, enabling the team to separate the challenge that increasing knowledge poses to memory from the actual performance of memory itself."
"Imagine someone who knows two people's birthdays and can recall them almost perfectly. Would you really want to say that person has a better memory than a person who knows the birthdays of 2000 people, but can 'only' match the right person to the right birthday nine times out of ten?" asks Ramscar.
"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," said Topics in Cognitive Science, Editors Wayne Gray and Thomas Hills.