Eileen Barker criticized the concept of mind control because it functioned to justify costly interventions such as deprogramming or exit counseling. She has also criticized some mental health professionals, including Singer, for accepting expert witness jobs in court cases involving NRMs. Her 1984 book, "" describes the religious conversion process to the Unification Church (whose members are sometimes informally referred to as "Moonies"), which had been one of the best known groups said to practice brainwashing. Barker spent close to seven years studying Unification Church members and wrote that she rejects the "brainwashing" theory, because it explains neither the many people who attended a recruitment meeting and did not become members, nor the voluntary disaffiliation of members.