I've read a few answers and concluded that for most of these answers,
concentration in meditation often implies unawareness of peripheral
stimuli. This confuses me. I usually have wisps as thoughts rather
than full blown thinking in meditation, but I don't particularly
become unaware of my environment.
Well, it does depend very much on what sort of concentration you want to achieve.
The concentration that leads to unawareness is absorption concentration. And that is not the type you want if you want to go for enlightenment. So, absorption is not the concentration of the Noble 8-fold Path.
Think about it. We all were and are absorbed in all kinds of stuff: reading, watching a movie, absorbed in thoughts, and so on. If absorption would be the way, half the planet would be enlightened.
The type of concentration the 8-fold Path speaks about is more of peaceful, unwavering composure of the mind. It is not focused on one particular thing, it is not absorbed. Some monks compared the needed concentration to the Hubble telescope (wide lens, wide field of awareness), it's not a laser.
The mind is unwavering, it keeps united and has the entire experience in one sight, so to speak. Think of a person standing on the top of a mountain being able to see everything with one look. That's what's meant with one pointedness.
And then, whatever thoughts, sights, sounds, smells, tastes or touches appear, it really doesn't matter. Because they are all caught in that one field of awareness. And since they are all in one picture there is no need for the mind to jump here or there, as it is with laser pointed concentration.
But again, depends on what you want to achieve.
Is such an experience very advanced? More so, does unawareness imply
literally not seeing/hearing/etc. or merely not being solicited by
Well, what do you call advanced? It really depends on the goal, doesn't it.
And yes, unawareness means not seeing, hearing and so on. Nice exercise, but completely useless for one who wants to achieve enlightenment.
Finally, I'm wondering whether the diminution of thoughts in itself
means little. Is attention placed upon the object consistently more
important than thought reduction?
Again, it depends on what you want to achieve.
There is no need to get rid of thoughts, if that's what you're asking. On the contrary, the first jhana is thinking and pondering. So, thinking and pondering on the right things. Example would be metta meditation, where you direct your attention to the thoughts of well wishing. And when there is momentum, the thoughts will continue automatically and attention can be directed at pity and sukkha, the next jhana. And so on.
But all the correct jhana have in common that they hold steady, once correctly established, so that you can go about your daily business without the mind starting to waver. Meaning you can be walking around, sitting, lying down, do the dishes, whatever, the mind will keep this unwavering quality.
Hope this helps.