Intraverbal naming and equivalence class formation in children.
Six typically developing children between 5 and 7 years of age underwent match-to-sample training to establish three-member equivalence classes after first acquiring a unique name for each stimulus. Horne and Lowe's (1996) naming hypothesis predicts that under those circumstances, match-to-sample training contingencies may establish intraverbal relations between the unique names, which in turn guide correct responses on a subsequent test for stimulus equivalence. Following training of baseline relations (AB and AC), participants received an equivalence test followed by an intraverbal test. Performance on the two tests co-varied, such that three participants passed both tests, and three participants failed repeated administrations of both tests, including a modified version of the equivalence test designed to promote intraverbal responding. The participants who failed the equivalence test, however, did so primarily due to poor performance in transitivity trials, but performed accurately in symmetry trials. After training of a third relation (BC), all three participants performed accurately in a symmetry test for the remaining untrained relations (BA, CA, and CB); two of them in the absence of relevant intraverbal repertoires.