March 1, 2008 Psychologists used an infrared camera to record reflections of the cornea to measure the amount of attention paid by someone walking on unfamiliar terrain. They found that even though walking seems to require very little attention, traversing complicated terrain like icy sidewalks or rocky paths can sap a walker's attention from another task performed at the same time. This leads to a situation where the walker thinks that he or she is paying closer attention to the surroundings than what is actually happening.
We start out crawling, then graduate to walking. After that we don't think much about it. But a new device used in a study by the military could save soldiers' lives and help civilians keep their feet on the ground in new surroundings.
This looks like a tactical training mission for the military but it's actually an exercise in walking. "Everyone worries about driving while distracted -- well you need to worry about walking while distracted, as well," says Jason Augustyn, a human factors psychologist for the U.S. Army Natick Research Development and Engineering Center (NRDEC) in Natick, Mass.
Augustyn feels that is especially true for soldiers walking on unfamiliar terrain, so he combined eye tracking with dual-tasking.
The device analyzes how a soldier allocates his attention while walking over terrain of varying complexity. It's equipped with an infrared camera that records corneal reflections. A second camera records the scene.
Soldiers are then asked to walk in a virtual reality room and perform a second task, like searching for a sniper. The results showed -- accuracy on the second task declined as terrain complexity increased.
"It shows you really have to pay attention to your surroundings -- where you are walking, what you are looking at, and if you don't you could get hurt … you could lose your life," says Tony Rogers, a research technician for NRDEC.
The findings appear to hold true for civilians, especially when walking with modern day distractions like cell phones and music players.
"You have to pay attention to what you are doing, especially if you are in a situation where the terrain is more complicated -- icy sidewalks, dirt gravel, leaves, things of that nature," says Augustyn.
The goal of the military is to show that added support may be needed in combat, depending upon the terrain soldier patrol.
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% 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.)
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 monitoring the controls at a nuclear power plant. The challenge is how to keep alert when nothing of concern is happing, so that when a problem does occur, it will be recognized and dealt with quickly.
PROBLEMS FROM PARKINSON'S: Many people suffering from Parkinson's disease experience progressively greater difficulty walking, a condition known as akinesia that is thought to result from depletion of the neurotransmitter dopamine in the brain's movement control centers. The most common gait problems are freezing and small little stuttering steps. Drug treatment can help alleviate this condition, but also has undesirable side effects.
The Human Factors and Ergonomics Society contributed to the information contained in the video portion of this report.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.