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I speak to a lot of corporate audiences, and regardless of the topic I come to discuss, I get a lot of general psychology questions, the most popular being about cognitive performance as people age.

Individuals in their 50s and 60s begin to worry that they are not going to be able to keep up mentally with their younger colleagues. But when does cognitive ability actually peak? As Joshua Hartshorne and Laura Germine discuss in a paper in the April, 2015 issue of Psychological Science, this question is not so easy to answer.

The big problem with this question is that cognitive ability is not a single thing. For example, researchers who study point out that cognitive tasks involve a mix of fluid intelligence (the ability to use and remember unfamiliar information on-line) and crystallized intelligence (reasoning from knowledge). Beyond that, there are all sorts of other factors that influence people’s performance, including the ability to read people’s emotions.

Hartshorne and Germine acknowledge this issue and then explore a variety of different tasks across the lifespan. They were interested in whether performance on different tasks peak at the same time.

The first two studies in this paper are focused on cognitive tasks. One looks at data from a large-scale administration of intelligence tests to adults ranging in age from 16 to 89. The second looks at performance on a range of cognitive tests collected from visitors to a website. The data from both studies suggests that performance on tests involving for brand new information tends to peak in the early 20s and to decline slowly—but steadily—from there. However, performance on tests involving knowledge (such as vocabulary or reading comprehension and general knowledge) rises steadily, peaking between the early 50s and early 60s.

A third study used Simon Baron-Cohen’s Reading the Mind in the Eyes task, which explores people’s ability to identify the emotion someone is experiencing—just from their eyes. This ability reached an initial peak around the age of 20 and then increased slightly through about the age of 50. Even the oldest adults in the sample were quite good at it.

The data analyzed in this paper were collected from studies between 1974 and 2012. One observation—called the Flynn effect, for James Flynn, who was one of the researchers—demonstrated that scores on intelligence tests have been rising for much of the 20th and 21st centuries. Consistent with the Flynn effect, scores on the tests in these studies also tended to increase over time. In addition, the age of on vocabulary tests got older as time went by. For those who took the test in the 1970s and early 1980s, peak performance was observed around the age of 40. In the most recent data, performance peaked after age 60.

One explanation for this finding is that people are engaging in more cognitively demanding work for longer periods of their lives now than they did in the past. This hard work staves off signs of for tests that involve broad knowledge.

There are two important conclusions to draw from this work:

First, people shouldn’t worry too much about cognitive declines. Knowledge is at the centerpiece of smart thinking, and knowledge-based abilities are excellent across the lifespan.

Second, the more mentally active you are, the more mentally effective you are (barring injuries to your brain and strokes). So take care of your brain and body, stay active, and relax.

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