Driving on the highway takes a lot of mental concentration and a little physical coordination. But because drivers are human, there is also a big role for emotion.

Imagine this: You are driving down the highway and you see a sign that says “Road work ahead, merge right.” You squeeze into the next lane, which starts to slow down, and watch the drivers to your left whiz by, expecting to be able to move over at the last second.

Right away, you are back in grade school, scowling at the bully who cut in the milk line. You fume as your lane – the good lane! – slows to a crawl, but you’ll get your revenge when those line cutters can’t skate in the left lane any more and have to move right. Then you make sure that you are so close to the car in front of you that there’s no room for them to get in.

You don’t get where you’re going any faster, but at least you have a feeling that justice was served.

But what if the selfish drivers in the left lane were really in the right?

Several states are trying to encourage a practice called “zipper merging” that moves traffic more safely and efficiently – and it’s not what your emotions have been telling you.

According to traffic planners in Kansas, Minnesota, Missouri and Washington state, the right thing is not changing lanes at the first warning of a lane closure – that will just slow that lane down, creating the dangerous situation that comes when adjacent lanes are moving at different speeds.

When they get to the obstacle, drivers should take turns, one from the left, one from the right, like the teeth of a zipper.

Traffic keeps moving, and nobody gets their feelings hurt. Instead, every driver has the experience of letting someone else go first, and getting the same treatment from somebody else. And transportation planners are aware that emotions have to be taken into account.

“When a rule is being violated by someone else, it frustrates us, it irritates us, it makes us angry,” Dwight Hennessy, a psychology professor at Buffalo State College in New York who specializes in traffic psychology, recently told The Associated Press. “We expect everyone else to follow the rules, and when they don’t and we know that they’re getting an advantage, it ticks us off.”

Zipper merging may not sound so novel to Maine drivers, because it’s already an informal practice in some high-traffic areas, like the Route 1 bridge entrance near Bath Iron Works. There are no signs or instructions – people have just figured it out.

Maine should join the states that have turned this kind of courteous driving into official state policy.