The claim that new religious movements recruit by coercive psychological technique, brainwashing, in the popular term, was for a period the central justification for the practice of deprogramming, in which members were seized and held until they renounced their affiliation. This movement was the most prominent target of both the claim and the practice.
The claim was testable, and it was tested. Eileen Barker spent some six years on a longitudinal study of British recruitment, following people from their first contact through the residential workshops that were said to be the mechanism of capture. If the technique worked as described, the people exposed to it should have joined at high rates and stayed.
The figures went the other way. Of those who attended a residential workshop, the large majority did not join at all. Of those who did join, a substantial proportion left within two years, of their own volition and without intervention. The attrition was high enough that the movement's retention problem, rather than its recruitment power, was the more striking finding.
That result did not settle every question, and Barker did not claim it did. Intense social pressure, sleep restriction, and the isolation of recruits from prior ties were real features of the workshops, and undue influence is a genuine phenomenon. What the data would not support was the strong version: an irresistible technique producing compliance in those exposed to it.
The strong version fared no better in American courts. Expert testimony asserting coercive persuasion in this context was excluded in several proceedings during the 1980s, and the relevant professional bodies declined to endorse it. Deprogramming itself generated criminal convictions for those carrying it out.
The residue matters for how the rest of this collection should be read. The reason a group is contested is rarely the reason first advanced against it, and the failure of the brainwashing thesis is not a defence of any particular movement. It removed one explanation and left the specific record of each group to be argued on its own facts.