Colville's "1D" corresponds entirely to your notion of performative roleplaying. By 1D he means characterisation via repeated mannerisms, catch-phrases, distinctive voice, etc. I was getting at the same thing when I referred to the gnome's fear of heights and hatred of fish.
But by "3D", Colville means something quite different. He means an approach to working out what my character does (he also refers to a GM doing 3D roleplaying, in which case he is talking about how the Gm decides what a NPC does). And the approach he has in mind is working out what my character does by drawing on my character's motivations, including possibly conflicting or not-fully-understood motivations.
I must have badly expressed my intent, for what I mean by "performative" covers both of those cases. Maybe "expressive" would have been a better word?
What I was trying to cover was all
portrayal of a character, not not just in accent and personality quirks but also this whole thing about figuring out what your character would do based on who you are trying to portray. The simple declaration of taking your attack action against orc A instead of orc B might by itself, with no additional acting, be an example of portrayal...of performative roleplaying...if the reason you are doing it is because there is some reason your character would make that specific choice (e.g., orc B is the more obvious target, but your character is secretly in love with the character orc A is attacking, or whatever.). It's performative because the goal is to create an accurate portrayal of this character.
What I'm trying to contrast that with is the goal of feeling an emotional link with your character, completely independent of how realistic/unrealistic, innovative/cliché, complex/simple, 1-dimensional/3-dimensional that character is.
The word "pawn" is thrown around (usually pejoratively) to suggest that without 'roleplaying' you are just moving a piece around on a board. But, for me, my character is a pawn if I don't feel, at least a little bit, that it's
me there in the action, fighting the dragon or leaping over the pit or sneaking past the guard. That's what I'm calling
experiential roleplaying. And I do think they are two different things, based just on my own experience that the two aspects haven't correlated, and (again, just speaking for myself) to some extent they conflict.