A problem with the way you're talking about mindspace: if affect is a coordinate of mindstates, you can't "change" or "update" the affect of a point in mindspace; that's just moving to another point in mindspace.

You're right. That was sloppy.

So what you probably actually mean is to move yourself to a different point in mindspace where affect=0 while "holding everything else constant".

It could be any smaller value of affect but yes, that's what I had in mind.

Consider a painful sensation. I claim that this pain is actually a composite phenomenon; it consists of a strong negative affective judgment (or series of such judgments) and a physical sensation. Not making an affective judgment in this case would mean that all that remains is the physical sensation. You would keep experiencing this physical sensation but not have a dying urge to do something about it (like shift your sitting position, for example).[1] As long as you make sure that you are not causing bodily damage, I think that observing pain in meditation can be a really great learning experience.

I've been able to clearly experience this distinction during meditation. Bizarrely, I've even had the experience of rapidly alternating between these modes, with the pain turning on and off like a light switch.

[1] This sounds like a bad habit to get into, but I haven't found that to be the case. I still know what pain feels like and know to do something about it, but it serves more like an indicator than as a burning hot iron searing your eyes.