In the 1950s some American films were made that featured brainwashing of POWs, including "The Rack", "The Bamboo Prison", "Toward the Unknown", and "The Fearmakers". "Forbidden Area" told the story of Soviet secret agents who had been brainwashed through classical conditioning by their own government so they wouldn't reveal their identities. In 1962 "The Manchurian Candidate" (based on the 1959 novel by Richard Condon) "put brainwashing front and center" by featuring a plot by the Soviet government to take over the United States by using a brainwashed sleeper agent for political assassination. The concept of brainwashing became popularly associated with the research of Russian psychologist Ivan Pavlov, which mostly involved dogs, not humans, as subjects. In "The Manchurian Candidate" the head brainwasher is "Dr. Yen Lo, of the Pavlov Institute."