Psychologically, middle age is often an appealing time because, all else being equal, it
can be a relatively placid period compared with what has come before. Our bodies aren't
changing as they did in adolescence; we're more likely to have a solid sense of who we
are and be skilled at a career. We still regard ourselves as active, but we have a tendency
to deceive ourselves into thinking that we are learning as we were before. We rarely
engage in tasks in which we must focus our attention as closely as we did when we were
younger, trying to learn a new vocabulary or master new skills. Such activities as reading
the newspaper, practicing a profession of many years, and speaking our own language are mostly the replay of mastered skills, not learning. By the time we hit our seventies, we
may not have systematically engaged the systems in the brain that regulate plasticity for
fifty years.