LEWISTON – What happened at the New York Wal-Mart on Black Friday where one worker was trampled to death is crowd behavior gone really bad.

Crowds behave differently than individuals or small groups where people know each other, said Jan Phillips, the associate dean for community relations at the Lewiston-Auburn College of the University of Southern Maine. Phillips has researched and written about consumer behavior.

In Black Friday crowds, “there aren’t leaders. There aren’t followers.” The only thing people have in common is they’re sharing the same space, she said. People may be less tolerant and less kind than they would be in small groups.

Black Friday shopping can go well, even with big crowds, when people in lines begin to interact and form relationships, Phillips said. That would include people who shop that day every year and recognize each other. “They take turns saving their place, someone goes off for coffee.”

Helping stage a safe Black Friday sale is “when the lines are set up and managed, rather than everybody coming full throttle with nameless, faceless crowds,” Phillips said.

Crowd behavior can go awry when there is no order, she said. “And there’s a perception of scarcity,” such as with the limited supply of deeply discounted televisions and video games. That perception of scarcity can worsen crowd behavior, Phillips said.

“It heightens this sense we’re all competing; we’re all in this for ourselves,” she said. Adding to the mix: Many Black Friday shoppers went without sleep and were out in the cold for hours.

Part of the success behind Black Friday sales is the stores are working to create the perception of scarcity to motivate the crowd to spend. The tricky part, Phillips said, is safely managing that spill of people.

There are famous cases of people trampled to death at rock concerts, Phillips said. “Part of what goes on once the crowd moves is you can’t stop. You’re pushed along.” Since people were trampled to death at rock concerts, civic centers have learned to control crowds, how to make sure people stay in the line as people move toward doors.

Stores can improve crowd behavior, Phillips said, by having added security, employees who walk the outside lines informing shoppers about the time and sales, she said. “To a degree, stores can encourage people to bond together.”