Reported March 2008

ON ONE'S TOES: Vigilance is an area of human factors and ergonomics research that looks at people's ability to stay focused on a task over long periods, such as someone simultaneously watching his or her feet and the surroundings, while monitoring the controls at a nuclear power plant. The challenge is how to keep alert when nothing of concern is happening, so when a problem does occur, it will be recognized and dealt with quickly.

HOW WE WALK: Walking is different from a running gait because only one foot at a time lifts off the ground. During forward motion, the leg that leaves the ground swings forward from the hip, like a pendulum. Then the leg strikes the ground with the heel and rolls through the toe in a motion similar to an inverted pendulum. The motion of the two legs is coordinated so that one foot or the other is always in contact with the ground -- a so-called 'double pendulum' strategy. The process of walking recovers about 60 percent of the energy expended thanks to the pendulum dynamics and the ground reaction force. The legs act as long levers that transfer ground reaction force to the spine.

TALKING CAN ALSO BE A DISTRACTION: In unconnected research, scientists found that subjects were able to perform a simple task quite easily. But when half the group was asked to take on an additional verbal task, their ability to perform the first task was hindered. This indicates that having a conversation, even with a hands-free cell phone device, can distract people while they walk, or while they drive.

The Human Factors and Ergonomics Society contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Jerry Whitaker, Chief, Public Affairs Office
U.S. Army Soldier Systems Center-Natick
(508) 233-5340
Jerry.Whitaker@natick.army.mil

Human Factors and Ergonomics Society
Santa Monica, CA 90406
(310) 394-1811
http://www.hfes.org