I've thought about this idea (without knowing there was a term for it!) wrt aging in real life. So many people seem to become increasingly caricature as they get older. The guy who likes woodworking and European travel becomes the embodiment of woodworking and European travel. It's all he talks about. His kids roll their eyes at Thanksgiving -- there dad goes again. Etc.
I've been playing around with metaphors, trying to get the flavor of this. I like the one about multiplying two vectors together, where small vector elements shrink, larger vector elements get (relatively) bigger. The vector becomes a more exaggerated version of what it was. And it makes intuitive sense: he spends more time wordworking, wordworking activities crowd out non-wordworking activities, his social engagements intersect wordworking, more of his friends become woodworking friends, and slowly the gravity of his internal world pulls everything in that direction. Nothing sinister about it.
I thought: how would you prevent such a thing? And should you?
Anyway, I'm rambling. But I would welcome any further pointers that could enrich my thinking about this idea.