I think posters above are wrong that it's possible to perform some action at such a moment... At least I can't. Performing actions is only possible if you're already lucid.

It's truly weird to know that you're in a dream but not be lucid. But it's not real lucidity. Any time that happened to me I later found my actions to have been totally unconscious, just like in normal dreams, so I believe it's impossible to execute a conscious action in this case.

Even if actions in such a dream seem conscious you know they're not once you analyze how they happened. When unconscious you act in a kind of "flow-fashion", unable to stop and start thinking what to do. There's no ability to pause and make choice. Dreams with knowing that it's a dream are such unconscious dreams, without an ability to choose to perform an action or an RC.