“…The following theoretical descriptions and assumptions constitute theoretical backgrounds with which the present results can be analyzed: Skinner's (1957) analysis of verbal behavior; relational frame theory (e.g., Hayes, 1991Hayes, , 1994Hayes, Barnes-Holmes, & Roche, 2001;Hayes & Hayes, 1989); Sidman's (1986Sidman's ( , 1994Sidman's ( , 2000 analysis in terms of stimulus equivalence; analyses based on contextual control (e.g., Dymond & Barnes, 1995;Gatch & Osborne, 1989;Griffee & Dougher, 2002;Lynch & Green, 1991;Meehan & Fields, 1995;Pérez-González & Martínez, 2007;Pérez-González & Serna, 1993Steel & Hayes, 1991); naming theory (e.g., Horne & Lowe, 1996); analyses in terms of intersecting classes (Sidman, 1994, pp. 528-530 & epilogue;see also Alonso-Álvarez & Pérez-González, 2003, 2006, and Mackay, Wilkinson, Rosenquist, & Farrell, 2003; and joint control (Lowenkron, 1997(Lowenkron, , 1998.…”