It's the N400.* I was super excited to read about it a while
   back because it's what I was looking for.* And then, when I
   timed my own spontaneous reaction, it fit perfectly.* Science
   confirmed :) It's the tie-in time for our semantic systems to go
   online - i.e - oh crap duck I duck - right at the 400ms mark. I
   actually started the movement at P300 but was aware of it at
   N400. [1]https://en.wikipedia.org/wiki/N400_%28neuroscience%29
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   1. https://en.wikipedia.org/wiki/N400_%28neuroscience%29