A CIA handbook on coercive interrogation methods, produced 40 years ago during the Vietnam War, shows that techniques such as those used in Iraq, Afghanistan and Guantanamo Bay, Cuba, have a long history with U.S. intelligence and were based on research and field experience.

Declassified 10 years ago, the training manual carries in its title the code word used for the CIA in Vietnam, "KUBARK Counterintelligence Interrogation -- July 1963." Used to train new interrogators, the handbook presents "basic information about coercive techniques available for use in the interrogation situation."

The specific coercive methods it describes echo today's news stories about Guantanamo and the Abu Ghraib prison in Iraq. At Abu Ghraib, for example, photographs and documents have shown that detainees were hooded, blindfolded, dressed in sloppy garb and forced to go naked.

The KUBARK manual suggests that, for "resistant" prisoners, the "circumstances of detention are arranged to enhance within the subject his feelings of being cut off from the known and the reassuring and of being plunged into the strange."

The 1963 handbook describes the benefits and disadvantages of techniques similar to those authorized for use at Abu Ghraib, such as forcing detainees to stand or sit in "stress positions," cutting off sources of light, disrupting their sleep and manipulating their diet.

And among the manual's conclusions: The threat of pain is a far more effective interrogation tool than actually inflicting pain, but threats of death do not help.

Like the lists of interrogation methods approved for Iraq and Guantanamo, the KUBARK manual offers a menu of options for confusing and weakening detainees. A neat or proud individual was to be given an outfit one or two sizes too large without a belt "so that he must hold his pants up," the manual said. Forced changes in diet and sleep patterns should be done "so that the subject becomes disorientated [and] is very likely to create feelings of fear and helplessness."

Tactics involving deprivation of accustomed sights, sounds, taste, smells and tactile sensations were presented as primary methods for producing stress, and mirror the techniques seen at Abu Ghraib. Lt. Gen. Ricardo S. Sanchez, the top U.S. military officer in Iraq, approved in September a list of methods that included "sensory deprivation," "minimum bread and water," "light control," enforced silence and yelling at prisoners. Those methods have since been barred in Iraq.

The KUBARK manual cited research supporting the effectiveness of the deprivations. "Results produced only after weeks or months of imprisonment in an ordinary cell can be duplicated in hours or days in a cell which has no light or weak artificial light which never varies, which is sound-proofed, and in which odors are eliminated," the manual said.

An experiment referred to in the handbook was done in the 1950s and involved conditions designed to produce stress before an interrogation -- similar to those applied to John Walker Lindh after his capture in Afghanistan. Lindh was tied to a stretcher naked and later held for long periods in a large metal container.

In the experiment done about 50 years earlier, volunteers were "placed in a tank-type respirator" with vents open so that the subjects could breathe but their arms and legs were enclosed in "rigid cylinders to inhibit movement and tactile contact." Lying on their backs in minimal artificial light, the subjects could not see their own bodies, and the respirator motor was the only sound.

Only six of the 17 volunteers completed the 36 hours of the experiment; the other 11 asked for early release -- four because of anxiety and panic, and the others because of physical discomfort.

The conclusion reached, the handbook said, was that "the early effect of such an environment is anxiety" and that "the stress becomes unbearable for most subjects," some of whom "lose touch with reality [and] focus inwardly."

The payoff of such techniques, the manual said, is that when the interrogator appears, he or she appears as a "reward of lessened anxiety . . . providing relief for growing discomfort," and that sometimes, as a result, "the questioner assumes a benevolent role."

When it comes to torture, however, the handbook advised that "the threat to inflict pain . . . can trigger fears more damaging than the immediate sensation of pain."

"In general, direct physical brutality creates only resentment, hostility and further defiance," the manual said.

Intense pain, interrogators were taught, "is quite likely to produce false confessions concocted as a means of escaping from distress."

While pain inflicted by others tends to create resistance in a subject, the manual said, "his resistance is likelier to be sapped by pain which he seems to inflict upon himself."

Reports from Iraq and Afghanistan indicate that detainees have been told to stand at attention for long periods or sit in "stress positions." In one of the photographs from Abu Ghraib, a hooded detainee is shown being forced to stand on a box with wires attached to his body. He was told he would get an electric shock if he moved. Seven military police soldiers have been charged in connection with the abuse shown in that and other photographs. Investigations continue into the role military interrogators played in those incidents.

In such situations, the manual said, the source of pain "is not the interrogator but the victim himself." And while the subject remains in that uncomfortable or painful position, he must be made to think that his captor could do something worse to him, creating in him the stress and anxiety the interrogator seeks.

Threats of death, however, were described as "worse than useless" because they can leave the prisoner thinking "that he is as likely to be condemned after compliance as before."

Experiments at that time also showed that creating physical weakness through prolonged exertion, extremes of heat, cold or moisture, or through drastic reduction of food or sleep do not work.

"The available evidence suggests that resistance is sapped principally by psychological rather than physical pressures," the handbook advised.