Steven Hayes and Russ Harris are the founders of ACT, which stands for Acceptance Commitment Therapy. I’m sure that with a quick search online you can find more information on the work these two men have done than this writer could provide. I am not educated in ACT. All I know is that the methods taught in the ACT program and the exercises I have tried to relieve anxiety and change ways of thinking that are not really helpful to me, work.
One of the exercises is to defuse thoughts that cause harm.
This little video gives you an idea of fusion vs defusion.