Coercive behaviour modification techniques may be used on aggressive, manipulative or 'independent' individuals, usually in prisons. Such techniques aim to weaken, undermine or remove the supports of old patterns of behaviour and old attitudes, either by removing the individual physically and preventing any communication with those he cares about or who can give him any reinforcement, or by 'proving' to him that those ideals and persons whom he respects are not worthy of it and should in fact be actively mistrusted. Methods used include social disorganization and the creation of mutual mistrust (achieved by spying on individuals and reporting back private material), tricking people into written statements which are then shown to others to convince individuals to trust no one, segregation of natural leaders, and drug assaults. The latter reduce prisoners to a vulnerable state of mind in which they are unable to respond with emotion (side-effects and after-effects may include: induction of a catatonic-like state, nausea, loss of appetite, impotence, liver damage, and hypertension severe enough to cause cardiac arrest). Other techniques used in adjunct to behavioural modification include torture, electric shocks, emetics, and surgical destruction of parts of the brain.