Evaluation of single and mixed verbal operant arrangements for teaching mands and tacts.

The purpose of this series of experiments was to evaluate the effects of mixed mand-tact arrangements on the acquisition of mands and tacts in preschool-aged children. In Experiment 1, the effects of three training arrangements (mand-only training, tact-only training, and mand-tact training) were investigated with 3 typically developing children. Rates of acquisition in single (mand-only and tact-only) versus mixed (mand-tact) presentation were comparable, in contrast to earlier investigations. Experiment 2 attempted to clarify the equivocal findings of Experiment 1 by directly replicating the Carroll and Hesse (1987) investigation with 2 typically developing children. Results again demonstrated no clear benefit of mixed verbal operant training on tact acquisition. In Experiment 3, these same arrangements were evaluated with a boy with autism and included assessments to determine that a relevant establishing operation was in effect prior to each mand training session. Experiment 3 again failed to demonstrate the facilitative effects of mand-tact training on the acquisition of mands or tacts. Taken together, the data from these three experiments fail to support the improved efficiency of mand-tact training suggested by prior studies. Findings are discussed in the context of future research investigating mixed verbal operant arrangements.