Emergence of visual-visual conditional discriminations.

We assessed the emergence of visual-visual conditional discriminations following training of vocal tact and intraverbal relations. Ten preschool-age children learned to vocally tact six visual stimuli, A1 through B3. Next, they learned to respond intraverbally to the dictated names of A1, A2, and A3 by vocalizing the names of B1, B2, and B3, respectively. Emergent A-B and B-A relations were tested in a visual-visual match-to-sample (MTS) task. Five of ten participants passed the test, with or without a prompt to tact the sample stimulus. Four of the five failed a reverse intraverbal test that involved responding to dictated names of B stimuli by vocalizing names of A stimuli. The remaining participants failed the MTS test, apparently due to failures to maintain the trained vocal responses throughout testing. Accurate MTS performance in the absence of bidirectional intraverbal relations appears to contradict Horne and Lowe's (1996) analysis of the possible role of intraverbal naming in emergent stimulus control.