ON a quiet street in a village in the Balkans, an accident suddenly puts an American peacekeeping force to the test. A Humvee has hit a car, and a child who has been injured in the collision lies unmoving on the ground. A medic leans over him. The child's mother cries out. A crowd of local residents gathers in the background. How they will react is anyone's guess.
A lieutenant arrives at the scene and is confronted by a number of variables. In addition to the chaos unfolding in the village, a nearby unit is radioing for help. Emotions -- not only the lieutenant's own and those of his sergeant, but also those of the panicked mother and the restive townspeople -- will clearly play a role in any decision he makes.
This seven-minute situation is a simulation, generated on a large computer screen with sophisticated animation, voice synthesis and voice recognition technology. It is the product of about six months of work here by three research groups at the University of Southern California: the Institute for Creative Technologies, largely financed by the Army to promote collaboration among the military, Hollywood and computer researchers; the Information Sciences Institute; and the Integrated Media Systems Center.
The only human player is the lieutenant. The rest of the characters, including the sergeant who has been conferring with the lieutenant, have been generated by the computer.
For years, the Pentagon has used computers to simulate a wide range of battlefield experiences as realistically as possible. The Army has simulators that allow hundreds of soldiers in different locations to engage in a tank battle on the same virtual battlefield. And the more sophisticated the models, the more adeptly they take into account the effects of noise, vibration, heat and long hours of marching on an individual or group.
But the modeling has gone only so far, confined for the most part to what the Pentagon calls doctrine, or prescribed procedure. A computer-generated mission rehearsal that models human behavior and the emotions that govern it crosses a military frontier.
"It's a complicated, unexpected situation where you have to deal with individuals and not just tanks," said Dr. Paul S. Rosenbloom, a computer scientist who is deputy director of the Intelligence Systems Division at the Information Sciences Institute.
Dr. Richard W. Pew, a principal scientist at BBN Technologies in Cambridge, Mass., and an expert on military simulations, said, "It's a big enough challenge to model the doctrine, but ultimately we'd like to model the variations because the reason these models are potentially useful for training is they behave the way real people do."
Such simulations are still experimental. But when they are ready, they will be used at bases around the country to train soldiers and officers alike to make decisions under stress....
...The exercise simulating the Balkans mission is one step toward introducing emotional individuals into a situation so people can be trained for complex tasks like peacekeeping duties. "If the only interaction you have with an enemy is at the end of a gun," Dr. Rosenbloom said, "you don't need to know that much about them."...
...Modeling the behavior of one's own forces is hard, but building such models for adversaries or foreign civilians is much harder, even when their cultural and ideological foundations may be well documented.
One focus of Dr. Silverman's research, for instance, is terrorist behavior. Dr. Silverman evaluates his models by comparing them with the actual motives and behaviors observed for various groups.
In one project he is working on, the human player is the leader of a squad guarding a checkpoint at a bridge. All the other participants are simulations. In the exercise, a school bus approaches, filled with women and children. The bus also holds armed terrorists who are planning an attack.
"Throughout the ages," Dr. Silverman said, "we have been taught that emotions are the opposite of rationality and that cold logic is devoid of emotions." But new research shows that most decisions are guided by emotions, he said. "It's ironic, but to build realistic, clever software agents, we are giving them emotions and the capability of emotionally reacting to events and actions."
Dr. Silverman is optimistic about how quickly the new direction in research will prove effective. "It's definitely coming together," he said. "We're at the early stage, and there's a lot more theory than data. It's very easy to program a theory, but much harder to ground that in data and say this actually duplicates how people behave. But the field is moving rapidly forward."
But Dr. Pew of BBN Technologies is less optimistic: "I'm not sanguine that in the next five years we'll be there. People are complicated. You never do exactly the same thing twice. Every situation you face is always a little bit different, so trying to build a model that can reflect the importance of that context is where the challenges are."
To make further advances, Dr. Pew said, will require closer cooperation between psychologists and computer scientists. "If we want to be more successful with computer models, we need to go deeper into the psychology of how people perform," he said. "Because many of the models are ginned up by computer scientists who don't know anything about human behavior."
GRAPHIC: Photos: (Institute for Creative Technologies)(pg. G1); Dr. Paul S. Rosenbloom is working on computer stimulations that will help soldiers deal with people as well as tanks. (Marissa Roth for The New York Times)(pg. G5)
Chart THE SITUATION: An American peacekeeping force has been deployed in the Balkans, and a lieutenant finds his unit in a potentially volatile encounter in a small town.
THE DECISION: You, as the lieutenant, must choose wheter to send two of your squads to help the other unit, or to have all stay put until the child is evacuated.
1) A HUMVEE driven by the Americans has collided with a civilian vehicle, and a boy riding in the car is seriously injured. 2) THE BOY'S MOTHER cries out in distress as a medic tells the lieutenant that the child must be evacuated by helicopter for treatment. 3) A SERGEANT briefs the lieutenant about the situation. Calls for reinforcements are coming in from another unit facing a threat nearby. 4) A CROWD begins to gather, potentially obstructing the helicopters landing.
(Institute for Creative Technologies) (pg. G1) *****
Yoshie