My BA year at university was spent researching critical and literal theories (and watching all 4 seasons of Prison Break): Marxism, Feminism, Post-Colonialism all really fascinating things which made me a better intellectual, a better writer and certainly affected some of my ways of thinking. Did it make me a better Actor? No.
Disclaimer: That's not to devalue that education, I'll happily have a debate on the Marxist elements inherent within Sweeney Todd until the cows come home!
This all bodes the question, how much practical knowledge do we need to take on a role, to be an actor? In my early stages of training the notion or research was hammered home! If I was playing Torvald Helmer in A Doll's House I would be expected to FULLY Research the given circumstances of the script. "Immerse yourself in the world of the play" explore the themes, what was it like for a middle aged bank manager in Norway? What were the social and economic factors of the time? Etc etc. if you had a heavily Stanislavski based teacher I'm sure you'll know what I mean. How much does all of this knowledge help me as an actor? Do the audience actually care that I've looked at all of this? Is there actually ever an opportunity do display this vast amount of research within my performance? No, that's not the Actor's job. Were I a director, that would be a whole different question. Or if an Actor wanted to appear clever while talking to Jonathan Ross about their up and coming play.
A question to pose to any Actor playing Nora Helmer in A Doll's House. Does Nora even know, or care about the feminist movement? Or women's rights? If there is something in the text to suggest she does, then go for it.
What is useful to know is the character's knowledge prior to any scene beginning. Facts, events, beliefs etc. Everything the writer has given you. If they know something that requires you to understand it to a similar level, then research becomes important. For instance if a character says 'le chat, elle ne reviendre, jamais....jamais' it is safe to note that they know the French for this phrase. Then you would want to know that means 'the cat, she will never, never return'. If it is knowledge that they can sew, then you should be able to too. That's a given circumstance of which it is the Actor's job to adhere to.
Once you have that knowledge then let's put our attention on the actor in front of us and observe and respond. Ascertain the CHARACTERS given circumstances, and then live truthfully under them.
Be clever, be a researcher, be studious, I can't get enough of it, it will enrich you as a person. Just don't get stuck within it as an actor. It helps only so much.
Feel free to comment, debate or question.