Emergence of untaught mands or tacts of novel adjective-object pairs as a function of instructional history.

We tested the effects of multiple exemplar instruction (MEI) on the emergence of untaught mands or tacts of adjective-object pairs in a multiple-probe design across four students with autism/developmental disabilities. None of the students emitted either mands or tacts for three sets of three adjective-object pairs (word sets counterbalanced across students and conditions) in pre-experimental probe trials. In the baseline phase, either mands or tacts were taught for the first adjective-object pairs to each student who then received probe trials for the untaught verbal operants. None of the students emitted the verbal operant that was not directly taught. In the MEI condition, a second set of adjective-object pairs was taught under alternating mand and tact conditions until both operants were mastered. Following mastery of the second set in the MEI condition, students were again probed for the untaught mands or tacts for the adjective-object pairs that were not in their repertoires when a single verbal operant was taught in baseline (the first set). All students emitted the untaught mands or tacts for the first set. Finally, a third set of adjective-object pairs was taught as tacts or mands and the untaught mands or tacts emerged. The data are discussed in terms of generative verbal behavior, abstraction of establishing operation control, and multiple exemplar instruction.