By Trudy E. Georgio, M.Ed., BCBA, LBA
Why is variability important? The operant nature of variability has important implications. Variability is controlled by discriminative stimuli and reinforcing consequences. Reinforcement of variations facilitates the acquisition of sometimes hard to learn novel responses. Creativity and problem solving depend on operant variability (Neuringer, 2002). Individuals with autism spectrum disorder tend to respond less variably than neurotypical individuals, which can result in difficulties to adapt. Miller and Neuringer (2000) demonstrated that direct reinforcement of variability may help to modify some of the behavioral stereotypes that are characteristic of autism.
With lag reinforcement schedules, a response is reinforced if it differs from previous responses. Lag schedules of reinforcement can be used for increasing response variability in both research and applied settings. Lag reinforcement schedules sometimes referred to as lag x variability schedule, where x represents the number of previous responses the current response must differ from to be reinforced (Lee et al., 2002).
The current (target) behavior must be different than previous X behaviors in order to access reinforcement. This schedule is a means to increase variability within a response class. The number of other responses is defined by the parameter of the lag schedule. For instance: For a Lag 1, the current response most differs from the response preceding it, For a Lag 2 the current response differs from the previous 2 responses, and so on. With Lag infinity, the individual is reinforced for a response that differs from all prior responses.
Esch, Esch, & Love (2009) used a Lag 1 schedule of reinforcement to increase vocal variability of 2 non-vocal verbal children with autism and low vocal variability. The results show a systematic increase in the variability of vocal responses. In this study, a vocal response that was topographically different from the previous trial was praised and preferred items were delivered. If no vocal response occurred after two presentations of the model or the previous vocal response was repeated, reinforcement was withheld.
Do you have any students that demonstrate low response variability? What are some behaviors that you could use lag schedules to teach?
Esch J.W, Esch B.E, Love J.R. Increasing vocal variability in children with autism using a lag schedule of reinforcement. The Analysis of Verbal Behavior. 2009;25:73–78.
Lee R, McComas J.J, Jawor J. The effects of differential and lag reinforcement schedules on varied verbal responding by individuals with autism. Journal of Applied Behavior Analysis. 2002;35:391–402.
Miller, N., & Neuringer, A. (2000). Reinforcing variability in adolescents with autism. Journal of Applied Behavior Analysis, 33, 151-165