People might take a little longer to respond to questions as they get older, but new research has said that's not because the brain is processing information more slowly, older people tend to take their time so they will not make mistakes. Human brains don't seem to lose dexterity until after age 60, suggested a new study in Nature Human Behaviour. This work flies in the face of previous studies that have said our mental speed reaches its peak when we're around age 20.
As we get older, responses don't come as quickly because of influences beyond cognitive acuity, said lead study author Dr. Mischa von Krause, a research fellow at Heidelberg University.
"Our research now shows that this slowing is not due to a reduction in cognitive processing speed. Until older adulthood, the speed of information processing in the task we studied barely changes," von Krause said.
As people get older, they aren't as impulsive. Our physical reflexes also slow down. Both of those factors change how we react to the world and temper our responses. Our brains aren't yet in decline, however, noted the researchers. People are more cautious when they make choices as they age, and are more likely to consider things that will reduce mistakes, added von Krause. The motor parts of our responses also get slower.
One caveat of this study is that elctrophysiological measurements were not taken, and the scientists relied on data from an online experiment that measured one task: how quickly people reacted in a brain test. Images and words would flash on the screen, and volunteers had to categorize them with their keyboard. Over 1.2 million people participated in the game, however, and computational tools and machine learning were used to analyze the results.
After people reached age 20, their responses started to get slower. But a careful assessment suggested that it wasn't because older brains were processing information more slowly; that happened only after people reached age 60. People in their twenties were more likely to opt for speed over accuracy. While the youngest participants, aged 14 to 16, were able to see the question and tap a response fastest, processing speed was at its height around age 30, then declined only slightly over time. People tended to make fewer mistakes as they got older, until they reached age 60, when there was a decline in performance.
"Authors of previous studies have typically interpreted slower reaction times in older people as evidence of cognitive slowing," von Krause explained. "By applying a mathematical model of the underlying cognitive processes, we were able to show that alternative explanations for the slow responses can better account for the data."
Gender, nationality or education level did not have any impact on people's decision-making abilities. "The age trends in mental speed were very similar across subgroups," von Krause said.
There was also variability in the age groups, and not every person who was older was slower, said von Krause. "Why some people manage to maintain a high mental speed even in old age is a very interesting avenue for future research."
More work will be needed to understand how the human brain changes as it ages, and whether other types of tasks are affected by cognitive changes that happen as we get older.