You're on the bus, and one of the only free seats is next to you. How, and why, do you stop another passenger sitting there? New research reveals the tactics commuters use to avoid each other, a practice the paper, published in Symbolic Interaction describes as 'nonsocial transient behavior.'

The study was carried out by Esther Kim, from Yale University, who chalked up thousands of miles of bus travel to examine the unspoken rules and behaviors of commuters.

Over three years Kim took coach trips across the United States. Kim's first trip, between Connecticut and New Mexico, took two days and 17 hours, and this was followed by further adventures from California to Illinois, Colorado to New York, and Texas to Nevada.

"We live in a world of strangers, where life in public spaces feels increasingly anonymous," said Kim. "However, avoiding other people actually requires quite a lot of effort and this is especially true in confined spaces like public transport."

Kim found that the greatest unspoken rule of bus travel is that if other seats are available you shouldn't sit next to someone else. As the passengers claimed, "It makes you look weird". When all the rows are filled and more passengers are getting aboard the seated passengers initiate a performance to strategically avoid anyone sitting next to them.

"I became what's known as an experienced traveler and I jotted down many of the different methods people use to avoid sitting next to someone else," said Kim. "We engage in all sorts of behavior to avoid others, pretending to be busy, checking phones, rummaging through bags, looking past people or falling asleep. Sometimes we even don a 'don't bother me face' or what's known as the 'hate stare'."

The best advice from Kim's fellow passengers was:

Avoid eye contact with other people

Lean against the window and stretch out your legs

Place a large bag on the empty seat

Sit on the aisle seat and turn on your iPod so you can pretend you can't hear people asking for the window seat.

Place several items on the spare seat so it's not worth the passenger's time waiting for you to move them.

Look out the window with a blank stare to look crazy

Pretend to be asleep

Put your coat on the seat to make it appear already taken

If all else fails, lie and say the seat has been taken by someone else

"This all changes however when it is announced that the bus will be full so all seats should be made available," Kim observed. "The objective changes, from sitting alone to sitting next to a 'normal' person."

Kim found that race, class, gender and other background characteristics were not key concerns for commuters when they discovered someone had to sit next them. They all just wanted to avoid the 'crazy person.'

"One rider told me the objective is just 'getting through the ride', and that I should avoid fat people who may sweat more and so may be more likely to smell," said Kim. "Motivating this nonsocial behavior is the fact that one's own comfort level is the rider's key concern, rather than the backgrounds of fellow passengers."

Kim found that this nonsocial behavior is also driven by safety concerns, especially for coach travel which is perceived to be dangerous with ill lit bus stations. Kim also found that passengers expected each other to be jaded by delays or other inconveniences.

"In a cafe, which is more relaxed, people often ask strangers to watch their stuff for a moment," said Kim. "Yet at bus stations that rarely happens as people assume their fellow passengers will be tired and stressed out."

"Ultimately this nonsocial behavior is due to the many frustrations of sharing a small public space together for a lengthy amount of time," concluded Kim. "Yet this deliberate disengagement is a calculated social action, which is part of a wider culture of social isolation in public spaces."

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