Some time ago I also had to brake hard because a car suddenly slowed down in front of me (nasa NLEX ako). The funny thing was, aside from looking in front, my automatic reaction was to look at my rear view mirror. True enough, another car was behind me braking hard too. Since I saw him, I did not stop immediately; umabante pa ako to the point I was almost touching the one in front. I did this to give the driver behind me time to stop. Buti na lang it was enough so as walang chain bangga kami!

Lesson: when braking hard, the hazard is not only in front; chances are there will be one apporaching behind!