Acceptance and commitment therapy (ACT) focuses on enhancing psychological flexibility in the service of achieving core life values. One thing that distinguishes ACT from other psychotherapies is its grounding in empirical behavioural science. The results of the latter suggest that the capacity for human language can produce seriously negative psychological effects under certain circumstances. ACT is a therapeutic approach in which the negative effects of human language are undermined so as to support flexible values based living. ACT therapeutic work involves six key processes proposed under the "hexaflex" model. ACT has received considerable empirical support at a number of different levels of analysis.