And Roleplaying is: "the act of making decisions about what a character would do when that character would do something different than what you would do." I know what you would do, but what would your character do?
The problem with this definition, based on discussions I've seen on this and other forums, is that some people have a funny notion of what "would" means.
For one thing, I just don't believe it's psychologically possible to leave yourself behind and make decisions without your own subconscious intruding. It's just not how our brains work. There are mountains of research that show we don't make decisions for the reasons we think we do. Even that act of trying to avoid doing what you would do is, in a roundabout way, making a decision based on what you would do.
For example, imagine that I think, "Well, I happen to know there's a trap there, but avoiding that trap would be 'metagaming' and I don't want to do that, so I'll step on the trap because
I think that's what my character would do." I'm really making the decision as the opposite of what
I would do, and then slapping a "what my character would do" label on it.
Here's where I see the problem:
1. It's a totally valid form of roleplaying to try (however quixotically) to make decisions as your character, not you.
2. However, that seems sometimes/often to get interpreted to mean that your character would definitely
not do what you would do, especially if you happen to have knowledge that would help your character make good decisions.
3. And then from there, people seem to want to project these self-imposed rules on other players. To wit: "You are only making that decision because you have player knowledge.
Your character would not do that." As if "what your character would do" is somehow deterministic. People make unpredictable decisions based on complex inputs, and there is no one answer. And god save me from a game where everybody is just supposed to do the most
likely thing.
The other problem I have with this form of roleplaying is that, at least in my experience (YMMV) if I try to too hard to separate myself from my character, I no longer experience the game as if I am the character. That is, if I'm focused on keeping myself out of the picture, and just portraying my character, then when the sidekick NPC who has been following me around for six levels dies, I'm pretending to be sad but I myself am not genuinely sad. Because, well, my character isn't me. I've been engaging in an outward-facing, performative sort of roleplaying, and I myself am not really in the game.
For all those reasons, my approach to the roleplaying side of D&D (and other games) is:
1. Keep myself in the character so that I experience the game emotionally
2. Pick and choose my moments to outwardly portray the character to greatest effect.
On this second point, I like to make an analogy to writing dialog: if you are portraying a character with an accent, writing ALL that character's dialog with funny spelling and contractions can be exhausting to read. All it takes is a few judicious misspellings to get the point across, and readers will then "hear" the accent in everything that character says. So it is with roleplaying (in my experience): if you occasionally do something really colorfully in character, then other players will tend to perceive your character in their imaginations as that character for the mundane things, too, even if you're not consciously trying to be in-character. (And, as a bonus,
you I lessen the risk of other players getting sick of
your my amateurish acting.)