Barnaby's story is that his psychological functioning peaked in midlife, plateaued until his late fifties, and then modestly declined for a while. at the end of his life his functioning declined dramatically. his story reflects:

The answer is the aging process.

Explanation:

Most people reflect the same cognitive changes as they age. A normal aging process involves a slight decrese in memory and though processing at around age sixty. However, most changes do not impede the person from functioning in society. Moreover, some abilities such as language use are likely to improve.

answer; geography and region;

answer; personal construct;