My IQ is somewhere in the 130s, and a standard deviation is usually something like 12-15 points, so taking advice from my future self would be like taking advice from a normal 100 IQ person now! I don't pay terribly much attention to what such people say... I'd still pay a lot of attention to any message from the future because my future dim elderly self has all the fruits of my higher IQ periods to draw on, but this observation is enough to largely eliminate the interest of contemporary averages.
My suggestion wasn't that older people would be smarter or think more clearly, or even have access to some fount of wisdom that the young don't have. It was that their values and preferences change. To take a made-up example (though more plausible than some I could think of), suppose that 95% of 60-year-olds say that they seriously regret having had any body piercings. If you at 25 are considering a body piercing, you might do your utility calculation figuring your enjoyment of it now on the plus side, and then subtracting your expected displeasure with it as you get older. This could conceivably come in to play on such questions as whether to spend those extra 2 years finishing your Ph.D. too.
Suppose 60% of practicing lawyers are miserable (because most practice of law is miserable). Bob the idealist is considering law school and expects that he will be happy practicing law. Then he learns the unhappiness rate and adjusts his expectation downward.
Is it more clear to say that Bob learned from an older cohort, or simply that Bob learned more about what the practice of law is like?
(Example changed because the piercing example equivocates possible mistakes by 16-year-olds and 25-year-olds in the 95% figure)
One thing that struck me in the 2011 survey was that 90% of LW respondents were under age 38. I'm 57 myself. It seems that often rationality in planning our lives depends on estimates of what values and utility functions we will hold in the future. Has anyone looked systematically at what projected older versions of themselves would think, based on what relevant groups of existing older folks think?
"You'll understand when you're older" is an annoying form of argument. Arguably there's some grain of truth there when a 7-year-old tells you that sex is disgusting and he or she will never ever think it's anything but incredibly gross. But you could explain hormonal changes that as a matter of empirical fact change opinions on that subject in the vast majority of cases. I can't think of anything that dramatic that distinguishes 60-year-olds or 80-year-olds from 20-year-olds.
My dim recollection of studies is that on the whole as people age they tend to be less idealistic, more resigned to society the way it is rather than how it might be, and more constrained by realities of politics and economics (for starters).
I don't presume to offer anything in this regard based on my age, and in any case I'm only a single person (a nihilist when pressed, but one who finds himself happier pretending not to be and working sporadically for rationality, truth, justice, love, and all that good stuff).
When I read of cryonics, what comes to my mind is the escalating costs of health care and (as I see it) the need to curb the development of expensive life-extending medical procedures. Cryonics sounds instead like an extremely expensive procedure. Maybe no one is suggesting it be covered by health insurance, and it's just an option that some people pay out of pocket for. Even so, the "health care is a right, not a privilege" sentiment will mean that if it was shown to work, everyone would want it, and (in my estimation) society would go completely haywire in an unpleasant way.
Now, the substance of the above has probably been discussed elsewhere at length; I raise it is an example because when I was 21 I would have thought of it very differently than I do now.