Related to http://lesswrong.com/lw/1mh/that_magical_click/1hd7
I've NOT been confused by the problem of overthinking in the middle of performing an action. I understand perfectly well the disadvantages of using system 2 in a situation where time is sufficiently limited.
And maybe there are some other fail modes where overthinking has some disadvantages.
But there's one situation where I'd often be accused by someone of "overthinking" something when I didn't even understand what they might mean, and that was in understanding concepts. I would think "Huh? How can thinking less about the concept you're explaining help me understand that concept more? I don't currently understand it; I can't just stay here! Even if you thought I needed to take longer to try and understand this, or that I needed more experience or to shorten the inferential gap, all of that would mean doing more thinking, not less."
Then I would think "Well, I must be misunderstanding the way they're using the word 'overthinking,' that's all." I'd ask for a clear explanation and...
"You're overthinking it."
Now I was overthinking the meaning of overthinking. This was really not good for my social reputation (or for their competency reputation in my own mind).
Now, I think I got it. At last, I got it, all on my own.
I'm asking them to help me draw precise lines around their concept in thingspace, and they're going along with it (at first) until they realize...they don't HAVE precise lines. There's nothing there TO understand, or if there is, they don't understand it, either. Then they use the get-out-of-jail-free card of "You're overthinking."
Honestly, most nerds probably take them at their word that the problem is with them, and may be used to there being subtle social things going on that they just won't easily understand, and if they do try to understand, they just look worse (for "overthinking" again), so this is a pretty good strategy for getting out of admitting that you don't know what you're talking about.