It was believed that the Chinese in North Korea used such techniques to disrupt the ability of captured troops to effectively organize and resist their imprisonment. British radio operator Robert W. Ford and British army Colonel James Carne also claimed that the Chinese subjected them to brainwashing techniques during their war-era imprisonment. After the war, two studies of the repatriation of American prisoners of war by Robert Lifton and by Edgar Schein concluded that brainwashing (called "thought reform" by Lifton and "coercive persuasion" by Schein) had a transient effect. Both researchers found that the Chinese mainly used coercive persuasion to disrupt the ability of the prisoners to organize and maintain morale and hence to escape. By placing the prisoners under conditions of physical and social deprivation and disruption, and then by offering them more comfortable situations such as better sleeping quarters, better food, warmer clothes or blankets, the Chinese did succeed in getting some of the prisoners to make anti-American statements. Nevertheless, the majority of prisoners did not actually adopt Communist beliefs, instead behaving as though they did in order to avoid the plausible threat of extreme physical abuse. Both researchers also concluded that such coercive persuasion succeeded only on a minority of POWs, and that the end-result of such coercion remained very unstable, as most of the individuals reverted to their previous condition soon after they left the coercive environment. In 1961 they both published books expanding on these findings. Schein published "Coercive Persuasion" and Lifton published "Thought Reform and the Psychology of Totalism". More recent writers including Mikhail Heller have suggested that Lifton's model of brainwashing may throw light on the use of mass propaganda in other communist states such as the former Soviet Union. In a summary published in 1963, Edgar Schein gave a background history of the precursor origins of the brainwashing phenomenon:  Thought reform contains elements which are evident in Chinese culture (emphasis on interpersonal sensitivity, learning by rote and self-cultivation); in methods of extracting confessions well known in the Papal Inquisition (13th century) and elaborated through the centuries, especially by the Russian secret police; in methods of organizing corrective prisons, mental hospitals and other institutions for producing value change; in methods used by religious sects, fraternal orders, political elites or primitive societies for converting or initiating new members. Thought reform techniques are consistent with psychological principles but were not explicitly derived from such principles. Mind-control theories from the Korean War era came under criticism in subsequent years. According to forensic psychologist Dick Anthony, the CIA invented the concept of "brainwashing" as a propaganda strategy to undercut communist claims that American POWs in Korean communist camps had voluntarily expressed sympathy for communism.