Lively young people, lame old people, that is a common prejudice, not only in terms of mobility, but also mental comprehension. An online experiment with more than a million participants by a team led by Mischa von Krause from the University of Heidelberg now refutes this view: As the working group writes in “Nature Human Behaviour”, the speed of cognitive information processing between the 20th and 60th age largely stable. Only then does the mental processing speed decrease.
In the test, the subjects had to assign pictures to the categories “white” or “black” people and words to the categories “good” or “bad” by pressing a button. It is an implicit association test (IAT) that is used to research prejudices, for example. However, this content played no role in their own work, write von Krause and Co. They used the data set in the sense of a reaction time task in which the duration of cognitive decisions was measured. They then correlated this with the age of the test subjects, who were between 10 and 80 years old.
Their reaction time actually increased with age: the average time for a correct answer peaked at around 20 years, as previous studies have shown. But this is not due to cognitive decline, writes the team, which comes to a different conclusion with the help of a mathematical model. “In our view, older subjects are slower because they answer more cautiously and concentrate more on avoiding mistakes,” says von Krause. Part of the reason the 20-year-olds were fastest was because they were the most willing to trade accuracy for speed. At the same time, the motor reaction speed decreases over the course of life: Older test participants simply needed longer to press the right button after they had found the right answer.