As we grow older, many people mention that they become forgetful and that their brains are not working as well as they used to when they were young. On the other hand, we know that from childhood onwards we become smarter and smarter. But when does this smartness peak?
In a video, Vanessa Hill, the writer, host and producer of BrainCraft, gives on overview of recent research on this question: At what age does our intelligence peak?
There is an outline of the video on the Huffington Post.
The way she defines intelligence it comprises reasoning, planning, problem solving, creativity, self-awareness, and learning. She then explains the theory of fluid and crystallised intelligence, with the former being the ability to reason and problem solve independently of acquired knowledge and the latter being the ability to apply learned knowledge. She then explains that fluid intelligence peaks in young adulthood and then declines, whereas crystallised intelligence remains stable until in our seventies. A long-term study now showed that our mental abilities, thus the combination of fluid and crystallised intelligence, increases until our late thirties or early forties, then remain stable until our mid-fifties or early sixties and only start declining in our late sixties. Thus, it seems that we are quite smart for a rather long time. She also mentions that this peak might differ between individuals.