The videotaped images of Los Angeles policemen taking turns clubbing and kicking a lone suspect with apparent abandon suggest for Dr. James McGee the animal instincts that surface when humans acting in groups get swept into a frenzy.
"Human beings are far less removed from our animal ancestors than we'd like to think," said Dr. McGee, director of psychology at the Sheppard and Enoch Pratt Hospital and a therapist for the Baltimore County Police Department.
"Humans are pack animals. Just looking at the tape could remind you of a pack of animals attacking a prey. You see a pack of lions bringing down the wildebeest, how they're all getting their licks in."
Psychologists who serve America's police departments seem to agree that the potential for senseless brutality exists within practically any police agency where officers face violence, drugs, high-powered weaponry and public disrespect for the jobs they perform.
It's up to the departments, they say, to screen out applicants who are psychologically ill-equipped for police work and to create an ethic that brutality is unacceptable. It's also imperative, they say, for departments to offer counseling to police officers who are boiling over with stress and to make it "OK" for officers to seek such assistance.
Some departments do these things, but many do not -- and psychologists seem to agree that the Los Angeles incident bears the earmarks of a department where intolerance is made morally acceptable from the top down and where officers who mete out curb-side justice are rewarded rather than disciplined.
"The capsule analysis is that this is a situation that got out of hand, and the very public nature of it implies that it is not an isolated incident," said Dr. Charles Bahn, a forensic psychologist at the John Jay College of Criminal Justice in New York who advises that city's police department.
"Police get a double message: a rhetorical message that it's not acceptable and a policies-and-practice message that it's not only acceptable but it earns you respect."
Dr. Bahn insists that "you don't need a national inquiry" to find police forces where brutality is acceptable and even commonplace. "All we have to do is look a little and we will find it in other American cities. You can determine what departments it takes place in -- those where brutality complaints are dismissed out of hand and where there's no counseling for the officers involved."
Far from branding police officers as bad people, the psychologists say law enforcement poses a pressure cooker of demands that can motivate good people to act with cruelty.
Dr. Harvey Schlossberg, a former New York City police officer who left the force to become a psychologist, said the people attracted to police work tend to be conservatives: believers in law and order, defenders of the status quo, opponents of non-conformity. On the job, they confront city streets that verge on anarchy.
"The amount of violence against police has increased with the kinds of weapons out there," said Dr. Schlossberg.
In response, he said, police officers come to see themselves as a minority group: "It becomes them and us. We're united against them. . . . One builds up a vigilante justice, a sense that the only way we can see justice is to strike out, to become judge and jury."
Dr. Schlossberg said the problem is compounded by the popular culture that glamorizes Clint Eastwood and Sylvester Stallone renegades for their cold determination to mete out justice no matter what. "It becomes very Machiavellian. The ends justify the means. That's what they're brought up on."
But he added, "Brutality is not indiscriminate. There's always an incident that triggers the brutality. What happens is that the party involved -- in this case, the policeman -- loses the perception of reality. They get caught up in the fantasy. As the momentum builds, the boundaries of fantasy and reality begin to fade."
When police officers respond en masse to a crime scene, said Dr. Bahn, their highest priority is to protect each other. A tricky group dynamic can take over.
Responsible behavior can prevail if everyone acts responsibly. "But if one person starts acting brutally, the balance moves toward manhandling or tough handling," Dr. Bahn said. "Even those who detest violence -- and there are officers who do -- will for reasons of group dynamics behave more violently than they otherwise would."
He said many police officers also feel that society has grown so cynical about the justice system and the get-tough promises of politicians that it has given them a mandate to punish criminals where they find them.
They may also get a mandate from their superiors: "In non-verbal ways, police officers who are known as physically tough are often allocated special honors and promotion opportunities within the department," Dr. Bahn said. "Without saying so, many chiefs imply that the officer is looked upon as heroic within his own department."
Many departments, including the ones in Baltimore County and city, put their applicants through rigorous psychological testing. The aim is to weed out people who suffer from mental disorders or high levels of stress. Departments are looking for a rare individual: someone who is intelligent and street-smart, aggressive but sensitive, quick-thinking but not overreactive.
Dr. Gilbert Clapperton, a psychologist who screens applicants for the Baltimore City department, said he finds 30 to 40 percent of the candidates he interviews to be psychologically unfit.
"I don't think it really registers with the average citizen," said Dr. McGee of Sheppard Pratt, "how much responsibility the average police officer has. They're given authority to strap on a firearm and go out on the street with a legally mandated power of arrest and, under some situations, the authority to shoot people.
"Here you have a low-paying job with crummy hours that is extremely dangerous, and yet the only people you can safely put in the job are very intelligent, competent, well put-together people who can tolerate high levels of stress and danger and be decisive and have excellent judgment. You're looking for jewels -- precision equipment -- but you're not prepared to pay them anything or give them much stature."
Dr. Daniel Juda, a psychologist at John Jay, said police who have seen their buddies killed in action, or who have skirted death themselves, suffer the same symptoms of post-traumatic stress disorder -- nightmares, flashbacks, emotional numbness -- do Vietnam War veterans.
Lashing out at suspects may be one response. But some officers carry their rage inside, with disastrous consequences.
"We have expected police officers somehow to self-medicate themselves while maintaining a macho image," Dr. Juda said. "This is an impossible chore. What they have done is drink, take drugs . . . suffer from depression and act out at home with horrible breakups of family."
Many psychologists refuse to pass off brutality as a symptom of stress. Virtually all police work involves high levels of stress. And most forces, they say, seem to do their work without rampant brutality.
It's poor leadership, they say, that tips the balance between a force that is in control of its emotions and one that vents its frustrations on the streets.
Maintaining discipline in the sprawling police forces of Los Angeles and New York is particularly difficult, said Dr. Bahn. New York employs about 30,000 officers in precincts spread across five boroughs.
"It's people in leadership of supervisory positions who either promote violence, tolerate violence, tolerate racial slurs, who will set the tone for the entire department," Dr. McGee said.