ACT

Origins & Influences

ACT emerged from a deliberate philosophical split within behavior therapy. Steven Hayes, trained in radical behaviorism and functional contextualism, became dissatisfied with cognitive therapy's emphasis on changing thought content — an approach he argued was actually inconsistent with behavioral principles because it treats thoughts as causes rather than behaviors. Hayes built ACT on Relational Frame Theory (RFT), a Skinnerian account of language and cognition, but drew equally from Eastern philosophy: the Buddhist concept of non-attachment became 'defusion,' mindfulness practice became present-moment awareness, and the acceptance posture echoes Zen's relationship to suffering. The result is a therapy that looks nothing like Skinner but is philosophically his descendant — it treats the function of thoughts (their context and the behavior they occasion) rather than their content, which is pure radical behaviorism. ACT's rejection of Beck was explicit and personal — Hayes publicly argued that CBT's cognitive model was theoretically incoherent. The irony is that ACT is now routinely classified as 'third-wave CBT,' a label Hayes has never embraced.