| Abstract: The seminal research on equivalence relations by Sidman (1994) and colleagues, which commenced in the early 1970s, led in the mid-1980s to the development of relational frame theory (RFT; Hayes, Barnes-Holmes, & Roche, 2001). The tutorial will present an overview of this 30 year-old unfolding research story and will consider some empirical and conceptual issues that appear to require focused attention as the story continues to unfold across the coming decades. In particular, the tutorial will commence by focusing on the historical and intellectual roots of RFT, identifying the work of Darwin, Wittgenstein, Skinner, and particularly Sidman as critically important. The basic units of analysis proposed by RFT, as a behavior-analytic account of human language and cognition, will then be considered. The impact these analytic units have had, and still have, on RFT research will also be reviewed. A relatively new RFT concept, known as the multi-dimensional multi-level (MDML) framework will be presented. A recent model of specific properties of relational framing, the differential arbitrarily applicable relational responding effects (DAARRE) model, will also be considered. Finally, a case will be made to integrate the MDML and the DAARRE model into a hyper-dimensional, multi-level (HDML) framework |