Here’s a possible answer: think about what it’s like when you learn something for the first time — for example how, when you are young, you learn to ride a bike or navigate your way home from school. It takes time to learn new tasks and to encode them in your memory. And when you are learning about the world for the first time, you are forming a fairly steady stream of new memories of events, places and people.
My grandfather, who died two years ago at age 93, used to say that things moved faster when you are older because it is, in fact, actually less of your life. When we are 2 going on 3, that’s 33% of our lives but when we are 49 going on 50, that’s only 2%. This came from a man who decided to learn the computer at age 85. So I think it is reasonable to assume that the article’s author is more accurate than my grandfather on this one.