2. Study 1

known as Theory of Mind (ToM) [3], has been an inspiration for psychologists studying typical and atypical development in children. Indeed, a search conducted using the filter "theory of mind" in PsycINFO, returned more than 6400 entries— including theses, books, and journal articles. An interest in these phenomena has also been shown by behavioral psychologists. The recently developed Relational Frame Theory (RFT) [4], which is a modern behavioral approach to the study of language and cognition, considers perspective-taking as generalized operant behavior that can be learned [5–7]. In line with the RFT approach, learning to respond to appropriate questions defined on the base of deictic relations — such as I-YOU, HERE-THERE, and NOW-THEN—, appears to be critical in establishing perspective-taking repertoires [8]. Such relations have been learned from a history of multiple exemplars of asking and responding to questions such as, "What am I doing now?", "What did you eat then?" or "Where were you jumping then?". Each time these questions are answered, the physical properties of environment are different. However, the relational properties of I-you, herethere, and now-then remain constant across all exemplars. That is to say, the so-called deictic relations are an abstraction of an individual's perspective of the world and of others, in other

words, deictic relations specify a relation in terms of the perspective of the speaker [4].

sitting on the black chair).

72 Behavior Analysis

nia or schizophrenia (e.g. [13, 16, 17]).

The first RFT study on perspective-taking in term of deictic relations was reported by Barnes-Holmes [5]. In this study, a testing and training protocol was developed for establishing the three deictic relations on the three levels of relational complexity (i.e., simple, reversed, and double reversed relational response) in young children. A simple relational response consists of relations in which none of the elements are reversed (e.g., "I-experimenter- am sitting here in a blue chair and you -participant- are sitting there in a black chair. Where are you sitting?"). In a reversed relational response, some of the elements are reversed (e.g., "If I were you and you were me, where would you be sitting?") and a correct response reflects this relational reversal (i.e., the experimenter is sitting in a black chair and the participant is sitting in a blue chair). In a double reversed relational response, two relations are reversed simultaneously (e.g., "If I were you and you were me and if here were there and there were here, where would you be sitting?") and a correct response would appear to require more complex derived relational activity (i.e., the experimenter would be sitting on the blue chair and the participant would be

Many studies have investigated the RFT approach to perspective-taking through the Barnes-Holmes protocol [8–14]. Studies such as those by Heagle and Rehfeldt [15] or Rehfeldt et al. [11] improved perspective-taking skills by means of reinforcement contingencies during the training trials for correct responses on the deictic relational protocol. Others [10, 14] established the relationship between deictic framing and ToM skills. This protocol has also shown that deictic responding can help to understand clinical concepts such as social anhedo-

In recent years, the format of the original protocol has been modified in different studies. For example, the approach used in Davlin et al. [18] and in Gilroy et al. [19] was an extension of the Barnes-Holmes deictic framing protocol using a story reading context. These authors used more naturalistic story reading procedures from storybook materials, resources readily available to young children. Vilardaga et al. [20] created scenarios systematically developed on the basis of core deictic relations, although different from each other and suited for natural
