Investigating the acquisition, generalization, and emergence of untrained verbal operants for mands acquired using the picture exchange communication system in adults with severe developmental disabilities.

This study compared the total amount of training time and total number of trial blocks for individuals with severe developmental disabilities to acquire mands under control of unconditioned establishing operations and mands under control of transitive conditioned establishing operations for manual sign and for the Picture Exchange Communication System (PECS). Also examined was the generalization of mands across settings and communicative partners, as well as the emergence of untrained tacts and intraverbals for mands acquired using PECS. Mands for preferred items and for items needed to complete a chained task were acquired more rapidly and in fewer training blocks for PECS than for manual sign. Moreover, mands established using PECS generalized across settings and communicative partners. Finally, untrained tacts and intraverbals using PECS were shown to emerge for some of the participants following PECS training. These results suggest that PECS may be a viable alternative communication system for adults with severe developmental disabilities who have little or no history of systematic instruction and limited imitative repertoires.