[craigyk]

I disagree. I think many non-genetic factors affect "intelligence", even on a day to day basis. I myself have been able to detect noticeable and substantial variations in my faculties over these time frames. Brain-training exercises might not increase intelligence (I don't know) but there was a period of time when I found them valuable as a evaluation tool- I would do some sudoku puzzles every morning to "test" my myself that day (a very specific and narrow definition of intelligence). Even between days where I didn't feel noticeably different, I would still sometimes see a large difference in average time to solving the puzzles ( ie. as much as ~1min 30sec vs. ~5min! ).

I found the "fast" days where usually better spent focusing on specific, hard problems that had been vexing me, whereas the "slow" days might be better spent multitasking, organizing and communicating with peers to explore new ideas. I never quite pinned down how to influence these variations... though I suspect it was a combination of sleep, stress, caffeine, etc. In the end, I just roll with it. I haven't done the daily testing in a while, but I still try to be hyper-aware of which "mode" I might be in.