The effects of lag schedules and preferred materials on variable responding in students with autism.

Effects of a Lag 1 reinforcement schedule on appropriate and varied responding to the social question, "What do you like to do?" and effects of the proportion of preferred stimuli present during training on the amount of varied responding in each session were investigated with students with autism. An ABAB reversal design and a multielement design were used to evaluate the effects of the Lag schedule and proportion of preferred stimuli, respectively. Results showed that a Lag 1 schedule was effective at increasing varied vocal responding for 2 of 3 participants. The proportion of stimuli that were preferred did not affect the amount of varied responding emitted.