Some mental abilities seem to improve as we get older

My 20 year old self was much better at making fast, bad decisions. Not taking the time to think through the higher order effects of those decisions. That 20 year old self lacks all the MOOCs I have taken, all the life and professional experience, 300+ non-fiction books.

I think at 20 I would have been a better test taker if we both started a college class right now but that is about it. I am way "smarter" or "more intelligent" though at 54 vs that 20 year old self. It isn't even close.

IMO much is because we are blind to ET Jaynes Mind Projection Fallacy in this area. We think of "intelligence" as a physical property like mass that gets weaker with age like muscles or bones. It is just such a given in our thinking and language that we can't help it.

My theory of the brain is that it has to choose between spending energy on learning or executing, and that we start out heavily favouring learning as kids and then it shifts to execution as we age. Also ADHD would be people who doesn't properly make that shift and never stops learning, which sounds good but it isn't very valuable if you don't have any brain power left to execute.

Another thing, ADHD shows that this isn't really a choice, your brain will determine how to allocate between learning and execution without asking you.

I sometimes return to a video game that I played when I was younger and that I remember being difficult. This will be a game that I haven't touched in years. And then, yes, I will be rusty at first. But pretty quickly, it more than comes back to me: I find that it is now easier than I remember it being many years ago. It's like I am now on some new learning curve with a higher plateau. And, the striking thing is that this must entirely be transfer learning, from other things I've done in the intervening years.

The OP reports something closer to a lab study, on the scale of things.

In the following video, a Stanford professor studying aging suggests young people are faster at integrating a lot of quickly incoming information to the point of making decisions on it, but older people are emotionally more secure and can even make younger people more productive if part of the group.

https://www.facebook.com/onemindorg/videos/567283167605557/

I agree with a lot of this. There is a slowdown in my reaction speed to say an incident or a bug or a feature design.

But I have so much knowledge and context built up already that when I do respond, the execution is much better and leads to success (success == incident fixed, bug fixed and design fully implemented/executed and makes money).

I genuinely think that companies who don't hire older engineers do themselves a disservice. No wonder only FAANGs sustain themselves over decades, not the one-hit wonders from silicon valley.

Some "duh" things get proven true and some get proven untrue. That's science.

Well duh. What mental abilities only stay the same or degrade since birth?

Our whole species is centered around the concept of learning, a more efficient mechanism for knowledge transfer than genetics, and the delivery of babies so premature they are helpless and useless for years.