The death of Sun Myung Moon, the man who founded the cult we know as the Moonies, has again focussed attention on brainwashing.
Dr Kathleen Taylor, author of Brainwashing: The Science of Thought Control, said it is not a "magical interference with the brain" as is portrayed in science-fiction films.
She defined brainwashing as "a very extreme coercive application of tried and tested techniques of psychology".
Prof Eileen Barker, from Inform, a government organisation providing information on minority religions, said that because it is a metaphor it is very difficult to know what is meant by brainwashing.
"Using terms like brainwashing just obfuscates rather than illuminates," she told the Today programme.
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