Cue: Any time my brain goes into "explaining" mode rather than "thinking" ("discovering") mode. These are rather distinct modes of mental activity and can be distinguished easily. "Explaining" is much more verbal and usually involves imagining a hypothetical audience, e.g. Anna Salamon or Less Wrong. When explaining I usually presume that my conclusion is correct and focus on optimizing the credibility and presentation of my arguments. "Actually thinking" is much more kinesthetic and "stressful" (in a not-particularly-negative sense of the word) and I feel a lot less certain about where I'm going. When in "explaining" mode (or, inversely, "skeptical" mode) my conceptual metaphors are also more visual: "I see where you're going with that, but..." or "I don't see how that is related to your earlier point about...". Explaining produces rationalizations by default but this is usually okay as the "rationalizations" are cached results from previous periods of "actually thinking"; of course, oftentimes it's introspectively unclear how much actual thought was put into reaching any given conclusion, and it's easy to assume that any conclusion previously reached by my brain must be correct.