Attention all drivers: the next time you’re out cruising the boulevard and the person in front of you has a bumper sticker that says, “Honk if you love…” you’d better think twice about hitting that horn. As reported in the Washington Post , a recent study has shown that the presence of bumper stickers is a good indication of how aggressive a driver can be and how likely their aggression will turn to road rage. It is believed that up to two-thirds of accidents on the road can somehow be attributed to aggressive driving

The study , out of Colorado State University, found that bumper stickers, window decals, and vanity plates are all good predictors of whether a driver will exhibit belligerent behavior in the form of honking, tailgating or even worse. The reason for this is because bumper stickers are a form territorial behavior, and by adorning one’s car with personal messages, a driver is in essence marking his or her territory.

Furthermore, the possibility of aggression seems proportional to the number of decorations on the car; the greater the number of decals, the greater the chance that any sort of provocation, however innocent it may be, will result in an angry response. While drivers of undecorated cars probably experience strong feelings just as often, they tend to keep it to themselves, while drivers who personalize their vehicles with visible markers are more likely to act out their feelings.

Interestingly, it didn’t seem to matter what the message was. Whether it said “Jesus Saves,” or “Gut Dear” made no difference, just the stickers themselves predicted territorial behavior.

When you get down to it, it seems like territorial behavior has been around for as long as humans, and for that matter all animals, have coexisted. Defending one’s territory ensured a safe and stable environment to raise a family and gather food, free from competition. While the constraints of human survival are not as stringent in the modern industrialized world, territory is still territory, and the need to defend it could very well be hard-wired in all of us.

According to the authors of the study, territory takes on three basic forms. There is personal territory, like one’s home or car, temporary territory, like a job workspace, and public territory, which would, of course, include streets and roads.

It may be perfectly reasonable for someone to defend their car or home, but problems arise when the lines between public and private space begin to blur, as is the case with road rage. In other words, when drivers begin acting as if they owned the roads, which believe it or not happens now and then, then everybody besides themselves (including you and I) becomes a hindrance and a bother.

So the next time that you feel the need to honk your horn or drive too closely to the minivan in front of you, it might not hurt to check the windows and bumper for any stickers, because even if the children were honor roll students at the local middle school, that will in no way predict the behavior of their mom or dad.