According to Newsweek, scientists led by Lucy Troup and her student William Szlemko of Colorado State University report in the June issue of the Journal of Applied Social Psychology that bumper stickers indicate territoriality. Drivers who have a strong sense of personal space while in their vehicle are more likely to be road-ragers, and the more bumper stickers and decals, the more territorial, the news report says.
The researchers found that people with lots of bumper stickers and decals on their car were 16% more likely to succumb to road rage. While 16% is not a huge probability, “The number of territory markers predicted road rage better than vehicle value, condition or any of the things that we normally associate with aggressive driving,” Szlemko told Nature magazine, according to Newsweek.
In addition, the study found the wording of bumper tickers was irrelevant. A person who plasters his car with religious stickers is just as likely to be aggressive as the person with gun rights messages.