Dr. Margaret Singer, a leading expert on brainwashing who testified in several high-profile cases contending that various groups inappropriately manipulated their members to control their behavior, died on Nov. 23 in Berkeley, Calif. She was 82.
The cause was respiratory failure, said her son, Sam.
In her long career, Dr. Singer investigated and testified about techniques used by North Koreans against American soldiers in wartime and the Symbionese Liberation Army's influence over the kidnapped heiress Patricia Hearst.
In the 1950's, Dr. Singer interviewed a number of American soldiers who had renounced the United States after returning from captivity in North Korea. The soldiers, she found, had been isolated and plied with propaganda, at times under the threat of physical harm.
Years later, she testified in defense of Ms. Hearst in a case that brought Dr. Singer national recognition and helped generate public curiosity about mind control.
Dr. Singer and her colleagues delved into a little known area of psychology at the trial, arguing that Ms. Hearst had helped rob a bank because she had been brainwashed to embrace the values of the Symbionese Liberation Army, which abducted her.
The group, the team argued, subjected Ms. Hearst to intensely stressful conditions, like isolating her from family and friends and locking her in a closet for six weeks, allowing its members to indoctrinate her and force a bizarre behavioral transformation.
Though Ms. Hearst was convicted, the trial bolstered Dr. Singer's reputation as an expert on mind control. In the following years, she repeatedly testified against the Unification Church, led by the Rev. Sun Myung Moon.
In one case, a libel suit against The Daily Mail of London, she argued that the church was a cult that brainwashed its members by showering them with intense affection, a process she called "love-bombing."
Dr. Singer said that she had interviewed hundreds of members of the church and testified that its techniques for mind control were more powerful than those used by the North Koreans on their war prisoners. The church lost its case.
"This has put us back to the start of the road again," Michael Marshall, an official of the church, said at the time of the lawsuit. "But we shall continue to fight for recognition and to show that we are a genuine religious movement."
Dr. Singer went on to testify as an expert witness in dozens of cases against groups she described as destructive cults. Former members of the groups or the anguished families of members, like some of the people who lost relatives among the Branch Davidians in the Waco, Tex., in 1993, would often seek her advice.
Several members of the People's Temple, with Dr. Singer's help, left that group before 900 people committed mass suicide in Guyana in 1978.
Dr. Singer would often help win lawsuits against groups that former members claimed had lured them into dark, insular worlds that left them psychologically traumatized.
"Her testimony would help people understand the clinical impact of a cult's manipulation and exploitation," said Dr. Richard Ofshe, a sociology professor at the University of California at Berkeley who worked with Dr. Singer for 20 years. "There was a constant stream of people who would go into these organizations and end up in psychiatric emergency rooms."
Dr. Singer's battles made her a target for harassment and death threats. At times, she found dead animals on her doorstep.
Margaret Thaler Singer was born in Denver and earned her bachelor's degree, master's degree and Ph.D. from the University of Denver. She became an adjunct professor at Berkeley in the 1950's.
Dr. Singer conducted several widely known studies on schizophrenia and was a renowned family therapist. She spent much of her career at Berkeley, but also taught at the University of Rochester and Albert Einstein College of Medicine, among others.
In addition to her son, Dr. Singer is survived by her husband, Dr. Jerome R. Singer; a daughter, Martha Singer, also of Berkeley; and five grandchildren.