I don't turn my head when I drive my car, because I have these awesome round convex mirrors on both of my side mirrors, which affords me a MUCH better view than just turning my head. Plus my 2-door Acura Integra has really small rear side windows so I can't see much out of those anyay (backing out of a parking spot and trying to see traffic coming from the right is a MAJOR pain).

My wife always turns her head when driving, and sometimes it looks like she's about to swerve in that direction when doing so

I've heard that putting your knee against the bike top tube when turning to look left can help keep the bike in a straight line. I want to try the hand on the knee thing, though. I need some way to keep the bike in line when I try to look back at my kid when he's in the trailer.