While it has long been believed that the brain slows as people age, recent research shows it may be a conscious choice that leads older people to emphasize accuracy over speed.
The research shows that healthy older people can be trained to respond faster in some decision-making tasks without hurting their accuracy, meaning their cognitive skills aren’t so different from younger adults.
“Many people think that it is just natural for older people’s brains to slow down as they age, but we’re finding that isn’t always true,” said Dr. Roger Ratcliff, a professor of psychology at Ohio State University and co-author of the studies. “At least in some situations, 70-year-olds may have response times similar to those of 25-year-olds.”
Ratcliff and his colleagues, who have been studying cognitive processes and aging in their lab for about a decade, recently extended their work to children.
He noted the results in children are what most scientists would expect: Very young children have slower response times and poorer accuracy compared to adults, but these improve as the children mature.
But the more interesting finding is that older adults don’t necessarily have slower brain processing than younger people, said Dr. Gail McKoon, a professor of psychology at Ohio State and co-author of the studies.
“Older people don’t want to make any errors at all, and that causes them to slow down,” she said. “We found that it is difficult to get them out of the habit, but they can with practice.”
To conduct the studies, Ratcliff developed a model that considers both reaction time and accuracy in timed tasks. Most models only consider one of these variables, he said.
“If you look at aging research, you find some studies that show older people are not impaired in accuracy, but other studies show that older people do suffer when it comes to speed. What this model does is look at both together to reconcile the results,” he said.
The researchers used several of the same experiments on children, young adults and the elderly.
In one experiment, participants were seated in front of a computer screen. Asterisks appear on the screen and the participants had to decide as quickly as possible whether there was a “small” number (31-50) or a “large” number (51-70) of asterisks. They pressed one of two keys on the keyboard, depending on their answer.
In another experiment, participants were shown a string of letters on the computer screen. They had to decide whether the letters were a word in English or not. Some were easy (the nonwords are a random string of letters) and some were hard (the nonwords are pronounceable, such as “nerse”).
In the child development study, the researchers used the asterisk test on students ranging from second grade to college age. Meanwhile, third graders and college-aged student participated in the word/nonword test.
The results showed that there was a rise in accuracy and decrease in response time on both tasks from the second- and third-graders to the college-age adults.
The younger children took longer than older children and adults to respond in the experiment, Ratcliff said. They, like the elderly, took longer to make up their mind. But the younger children were also less accurate than younger adults in this study.
“Younger children are not able to make as good of use of the information they are presented, so they are less accurate,” Ratcliff said. “That improves as they mature.”
Older adults show a different pattern, he said. In a study published in the journal Cognitive Psychology, Ratcliff and colleagues compared college-age subjects, older adults aged 60-74, and older adults aged 75-90. Using the same asterisk and word/nonword tests, they found there was little difference in accuracy among the groups, even the oldest of participants.
However, the college students had faster response times than the 60-74 year olds, who were faster than the 75-90 year olds.
But the slower response times are not all the result of a decline in skills among older adults, the researchers say. In another study, the researchers encouraged older adults to go faster on the tests. When they did, the difference in their response times compared to college-age students decreased significantly.
“For these simple tasks, decision-making speed and accuracy is intact, even up to 85 and 90 years old,” McKoon said.
That doesn’t mean there are no effects of aging on decision-making speed and accuracy, Ratcliff said. In a study in the Journal of Experimental Psychology: General, Ratcliff, McKoon and another colleague found that accuracy for “associative memory” does decline as people age. For example, older people were much less likely to remember if they had studied a pair of words together than younger adults.
The research suggests there should be greater optimism about the cognitive skills of seniors, Ratcliff said.
“The older view was that all cognitive processes decline at the same rate as people age,” Ratcliff said. “We’re finding that there isn’t such a uniform decline. There are some things that older people do nearly as well as young people.”
Source: The Ohio State University