Things are a little different around these parts...

Signaling in advance of a lane-change is taken as a sign of utter foolishness in the Northeast, and virtually always results in the signaller getting blocked in - not only by the guy that could have yielded to him, but also by the entire line of cars behind him. The same holds true for semis, which is why they hate driving the I-95 corridor through NY, CT, RI and MA. Once you get into NH and ME, the road civility level improves. Anyway, this also explains why the truckers often give little to no notice of their lane changes.

Lighting the blinker is a legal formality to be performed after the lane-change manoeuver is inevitable and there's nothing the other guy can do about it. I have a friend who is so gleeful about making a sneaky lane-change stick that when he signals it, he hits the turn signal briefly several times in a row, so the blinking appears slower than normal. Totally obnoxious. Kinda funny, though, if you are not on the receiving end of it.