A team of psychologists from Heidelberg University has recently found that, contrary to previous widespread assumptions, mental speed – the speed at which we respond to issues requiring rapid decision-making – does not change substantially between the ages of 20 and 60, and starts deteriorating only at older ages.
“The common assumption is that the older we get, the more slowly we react to external stimuli. If that were so, mental speed would be fastest at the age of about twenty and would then decline with increasing age,” said study lead author Mischa von Krause, a postdoctoral researcher at Heidelberg.
Dr. von Kraus and his colleagues re-evaluated data from a large-scale online experiment with 1.2 million participants that was initially designed to study implicit biases. In the initial study, the participants had to press a button to sort pictures of individuals in the categories “white” and “black” and words into the categories “good” and “bad.” According to Dr. von Krause, the content focus was not important for the new study. Instead, the large dataset was used as an example of a response-time task to measure the duration of cognitive decisions.
Although the data analysis showed that, on average, the response times of the subjects increased with age, applying a complex mathematical model helped the scientists discover that, in fact, this phenomenon was not due to changes in mental speed. “Instead, we think that older test subjects are mainly slower because they reply more cautiously and concentrate more on avoiding mistakes,” said Dr. von Krause. Moreover, motor execution speed slows down with age, with older participants needing more time to press the appropriate button after finding the right answer.
The findings also suggest that, after the age of 60, average information processing speed only progressively declined. “It looks as though, in the course of our life, we don’t need to fear any substantial losses of mental speed – particularly not in the course of a typical working life,” concluded Dr. von Krause.
The study is published in the journal Nature Human Behavior.