Bumper Sticker Road Rage

I heard the other day that people who put bumper stickers on their vehicle (window decals don't count) tend to be more aggressive drivers and exhibit road rage more often than those who keep their bumpers clean. Why? People who attach bumper stickers view the car as an extension of themselves. They personalize it; therefore, when someone cuts them off in traffic it is a personal offense committed against the car as a part of them, as opposed to an offense committed against just the car. Interesting. My neighbor has at least 15 bumper stickers on her car. Remind me to stay away.