primary authors of ACT and of the corresponding theories of human behavior, relational frame theory (RFT) and functional contextualism (FC), recommended their approach as the proverbial holy grail of psychological therapies. In 2012, in the preface to the second edition of Acceptance and Commitment Therapy, the authors clarified that "ACT has not been created to undercut the traditions from which it came, nor does it claim to be a panacea." A meta-analysis by Öst in 2008 concluded that ACT did not yet qualify as an "empirically supported treatment", that the research methodology for ACT was less stringent than cognitive behavioral therapy, and that the mean effect size was moderate. Supporters of ACT challenged those conclusions by showing that the quality difference in Öst's review was accounted for by the larger number of funded trials in the CBT comparison group. A 2015 review noted that research methodologies had improved since the studies described in the 2008 meta-analysis by Öst. Some published articles in clinical psychology have argued that ACT is not different from other interventions. In 2007, Stefan Hofmann argued that ACT is similar to the much older Morita therapy and to other old holistic and humanistic therapies. See also Behavioral psychotherapy Contextualism Defence mechanism Humanistic psychology Positive psychology Solution-focused brief therapy References External links Contextualpsychology.org – Home for the Association for Contextual Behavioral Science, a professional organization dedicated to ACT, RFT, and functional contextualism. Also helpful for training opportunities for professionals interested in ACT and RFT. Most ACT workshops worldwide are listed here. Behaviorism Cognitive behavioral therapy Mindfulness (psychology) Treatment of obsessive–compulsive disorder