It almost sounds like people try harder and harder to keep up with societal expectations of continued "sharpness"... until they hit some age where cultural norms say they aren't expected to be sharp any more. And then they stop trying, which causes an outsized decline as their lowered expectations of their own capability, feeds into lowered capability, which feeds back into further-lowered expectations.
could be, I really don't know. I can imagine perfectly benign scenarios too; if our long-term memory grows with time, maybe there's just more possible connections/associations to filter out with time too, so that decision just becomes harder, with only the deeper old age being simply tissue decline, the exhaustion of cognitive reserves etc.
Somewhat relatedly, I think I heard on some old Skeptic's guide to the universe episode about an experiment with some nootropic, maybe it was a racetam though I think it was mondafinil, and this kind of reaction time to response accuracy tradeoff was observed, on young healthy adults. Those with less correct answers slowed down, presumably concentrated better and gave better answers, but those already good at whatever the task was simply were slower and yet no better.
>And then they stop trying, which causes an outsized decline as their lowered expectations of their own capability
As if there are no physiological factors at play?
I mean, tons of studies have shown declining mental capacity, degenerative diseases increase with age, etc. Even in animals that have no, or much less, "societal expectations for sharpness".
