(It’s not the length of the wait.)

The boredom issue has been tackled in myriad ways—from the mirrors next to elevator banks to the TVs in dentist’s waiting rooms. Larson mentions a clever solution from the Manhattan Savings Bank, which once hired a concert pianist to play in its lobby as customers waited for tellers. “But Disney has been the absolute master of this aspect of queue psychology,” says Larson. “You might wait 45 minutes for an 8-minute ride at Disney World. But they’ll make you feel like the ride has started while you’re still on line. They build excitement and provide all kinds of diversions in the queue channel.” Video screens tease the thrills ahead, and a series of varied chambers that the queue moves through creates a sense of progress. Another solution: those buzzing pagers that restaurants in malls sometimes give you while you’re waiting for a table. Instead of focusing on the misery of the wait, you can go off and entertain yourself—secure in the knowledge that you’ll be alerted when it’s your turn.

How to play the expectations game? Studies show that we’re much more patient when we’re given an idea of how long we’ll be waiting, instead of wondering whether it will be three minutes or three hours. So, for example, some New York City subway platforms now feature digital displays featuring estimated arrival times for the next few trains. But again, Disney is the master. It posts estimated wait times next to various spots in its long queues—but, according to Larson, it pads the times so you always get to the head of the line more quickly than you’d expected: “You think, ‘We’re 10 minutes ahead of schedule!’ and so you’re happy.”

Perhaps the most emotional issue in the world of queuing is the human quest for fairness. “When we see people arrive after us and get served before us we get very angry,” says Larson. “We can remember it for days, sometimes. And there have been incidents of ‘queue rage.’ People have drawn knives and guns.”

Sometimes we will make exceptions. We seem to be OK with the idea of an express lane at the supermarket—someone buying one roll of paper towels shouldn’t be forced to wait behind someone buying a full cart of groceries. We also allow for differing priorities at an ER, with more critical cases being admitted first even if they showed up last.

But in most situations, we demand social fairness. No one is more important than anyone else, and everyone should be served in the order he or she arrived. No doubt you’ve experienced mild queue rage when you choose the wrong line at a fast food counter or a drug store, watching people in the other lines zoom ahead of you.

To solve this problem, some genius (Wendy’s, American Airlines, and Citibank are among the companies that claim to be originators) invented the serpentine line. The serpentine line funnels all customers into one big snaking queue, demarcated by ropes or barriers. When you reach the head of the queue, you are directed to the next available server, or teller, or customs official. The serpentine line isn’t always faster than a simple scrum before an array of cash registers. But it offers important solace: You absolutely never have to see someone arrive after you and get served before you.

Larson says he was once at a queuing theory conference where the hotel checkout line became quite long and was populated mainly by queuing theorists. “We insisted on forming our own serpentine line,” he says. “The lobby wasn’t designed for it and it looked extremely messy. The hotel manager was unhappy. If we’d just dispersed into six parallel lines at the checkout desk the wait might have been shorter and less chaotic. But it would have been less fair.”