On Oct. 19, leaders of several medical organizations flew to the U.S. Navy detention facility at Guantanamo Bay, Cuba. After meeting with officials and two psychologists who served as consultants during interrogations with detainees, a vigorous debate sprang up among the experts over the ethics of physicians and caregivers participating in the debriefing of prisoners.

The debate, which participants said was conducted in earnest over a lengthy dinner at Andrews Air Force Base after they returned from Cuba, explored concerns that medical experts in general, and psychiatrists and psychologists in particular, have aided U.S. government interrogations in Guantanamo Bay, Iraq and Afghanistan, often by applying their insights into human behavior to break the will of prisoners.

Although the Bush administration has asserted that it does not condone or practice torture, articles in prominent medical forums such as the New England Journal of Medicine have said that doctors and behavioral scientists have violated ethical norms while interrogating terrorism suspects at the behest of the U.S. government and become "complicit in torture."

This weekend, the American Psychiatric Association came to the conclusion that psychiatrists should never participate in coercive interrogations, or even lend advice to government officials carrying out interrogations that involve sleep deprivation, threats, humiliation, sensory deprivation or the use of prolonged stress positions, according to the group's president, Steven S. Sharfstein.

The move comes as officials of the American Medical Association are weighing the ethics of doctors helping interrogators, and it follows a call by the American Psychological Association this summer for its members to abjure participation in cruel and degrading techniques. All the groups have long proscribed torture.

The psychiatrists' policy effectively says that numerous techniques practiced by interrogators at Guantanamo Bay and elsewhere are unethical for psychiatrists to be involved with, said Sharfstein, who is also president and chief executive of the nonprofit Sheppard Pratt behavioral health system based in Baltimore. "It has to do with the profession and the perception of the profession," said Sharfstein, who explained that the restrictions applied even to psychiatrists who did not have a doctor-patient relationship with prisoners. "You are never not a physician."

While the American Psychological Association also ruled this summer that cruel and degrading techniques were out of bounds for psychologists, the group has not spelled out exactly what specific techniques that would allow and disallow.

Many techniques to break the will of prisoners have come from psychological studies of normal people, as well as animal experiments that have explored the boundaries of extreme fear and helplessness.

Ironically, criticism of such techniques has also come from behavioral scientists who have studied what happens to people when they are given the power to inflict suffering. In one famous experiment conducted by Stanford psychologist Philip G. Zimbardo, ordinary people turned into sadists when they were given the authority of prison guards over other volunteers who were "prisoners." They were dehumanized by being stripped, searched and subjected to various humiliations.

Stripping detainees was routine practice during interrogations at the Abu Ghraib prison in Baghdad, according to the report of an independent panel led by former defense secretary James R. Schlesinger in August 2004, and has been reported at other U.S.-run detention centers, including Guantanamo Bay.

That technique does not qualify as torture according to the definitions of U.S. officials. But the report concluded that "the stripping away of clothing may have had the unintended consequence of dehumanizing detainees" and that "the process of dehumanization lowers the moral and cultural barriers that usually preclude the abusive treatment of others."

"It is possible that some doctors, nurses, or medics took steps, of which we are not yet aware, to oppose the torture," psychiatrist Robert Jay Lifton wrote in a New England Journal of Medicine article last year that called attention to the role of doctors in prison abuse. "It is certain that many more did not." Stephen Behnke, director of the American Psychological Association's ethics office, said a task force had decided that psychologists could participate in interrogations because they had expertise that could aid national security and law enforcement.

But while the association says members should never participate in torture or cruel, inhuman and degrading treatment, Behnke and Ronald F. Levant, president of the association, did not offer clear definitions of what techniques those terms would not permit. "There are going to [be] behaviors that will fall into a gray area," Behnke said in an interview. "For example, isolation for a very brief period of time, for a matter of minutes, will not constitute cruel or unusual or degrading treatment."

About whether removing detainees' clothes during interrogations, as described in the Schlesinger report, crossed the boundary, Behnke said the association's ethics committee would soon be coming out with a casebook that explored specific behaviors and prohibitions. In his own view, Behnke said, "forcibly removing a detainee's clothes for the purpose of eliciting information . . . is degrading."

James Coyne, a psychologist at the University of Pennsylvania, said the ethics task force that came up with the guidelines included psychologists who were involved with U.S. government interrogations of detainees. Coyne has previously criticized the psychological association for not ruling out participation in the kind of interrogations reported from Guantanamo Bay and elsewhere.

He said the association had "called in the foxes to look after the henhouse." Sharfstein, the American Psychiatric Association president, said military officials were themselves debating about the appropriate role for doctors.

"There is a long history in military ethics of not putting doctors in positions where they can harm or kill," said Nancy Sherman, a former teacher of ethics at the U.S. Naval Academy in Annapolis, who was part of the team that visited the Guantanamo Bay facility last month. "The doctor's role is to the healing profession and not to the mission."

Detainees at Guantanamo Bay, Cuba, have been subjected to various interrogation techniques -- including being stripped to dehumanize them. Psychologists are thought to have insights that could help law enforcement.

Steven S. Sharfstein heads the psychiatric group that banned aiding coercive interrogations.