THE BEHAVIOR ANALYST TODAY VOLUME 5, ISSUE NO. 1 15 Perspective-Taking and Theory of Mind A Relational Frame Account Yvonne Barnes-Holmes, Louise McHugh, & Dermot Barnes-Holmes National University of Ireland, Maynooth Cognitive perspective- taking has attracted considerable attention in the mainstream developmental literature, and is most commonly studied under the rubric of Theory of Mind. The current article reviews the levels of understanding of informational states that are believed to underlie cognitive perspective- taking from this conceptual framework. An alternative approach to perspective-taking from a functional behavioral framework is also presented. The concepts and methodologies behind this approach are driven by a modern behavioral account of human language and cognition known as Relational Frame Theory. As well as providing a brief summary of the core concepts of Relational Frame Theory, the article presents the relational frame account of cognitive perspective- taking. The empirical evidence in support of this view of perspective-taking as well as related research on false belief and deception are reviewed. The overlap between the Theory of Mind and Relational Frame Theory approaches to perspective-taking is discussed. Key words: Perspective-taking; theory of mind; Relational Frame Theory; false belief; deception. Relational Frame Theory (RFT) is a modern behavioral and functional account of human language and cognition (Hayes, Barnes-Holmes, & Roche, 2001). The theory draws primarily on the concept of derived multiple stimulus relations and a behavioral process called arbitrarily applicable relational responding as the core features of verbal behavior. Accordingly, RFT argues that this process underlies many, if not all, of the basic phenomena that comprise human language and cognition, including, naming, storytelling, humor, metaphor, perspective-taking, and even spirituality. In the current paper, we are concerned primarily with the RFT account of perspective-taking as an example of a complex human psychological phenomenon that can be accounted for in behavior analytic terms. In the first part of the article we present the basic concepts of RFT. In Part 2 we outline the RFT approach to cognitive perspective-taking, and review the empirical evidence that supports this view, drawing comparisons with the more traditional account of this phenomenon known as Theory of Mind (ToM). Relational Frame Theory and Derived Relational Responding According to RFT, relational responding in accordance with arbitrary stimulus relations is not controlled solely by formal stimulus properties, but by contextual cues. For example, if you are instructed that ‘A is the same as B, and B is the same as C’, then as a verbally sophisticated organism you will readily derive, without additional information, that ‘A is the same as C’ (although A and C are not physically the same stimulus). In the language of RFT, the derived sameness relation between A and C is controlled by contextual cues, in this case the word “same”, the relational functions of which have been established by the verbal community. For RFT, deriving the A-C relation in this case is an example of arbitrarily applicable relational responding because the “sameness” of the relation is arbitrarily applied and can be modified by social whim. For example, I could now tell you that ‘A is larger than B and B is larger than C’. In this case, you would derive new relations (‘A is larger than C and C smaller than A’), and this relational response provides an example of the relational frame of comparison (rather than sameness). The literature on RFT has identified a number of patterns or families of arbitrarily applicable relational responding, referred to as relational frames (Hayes, Fox, Gifford, Wilson, Barnes-Holmes, & Healy, 2001). Although these frames are distinctive in various ways, they all have the same three