Variability as a subject matter in a science of behavior: Reply to commentaries

Abstract

In my article I claimed that studies of operant variability that use a lag n or threshold procedure and measure the obtained variability through the change in U value fail to provide direct evidence that variability is an operant dimension of behavior. To do so, I adopted Catania's (1973) concept of the operant, which takes the increase in the overlap between an R distribution and an S distribution as the behavioral process that demonstrates an operant relation. This increase in overlap can be measured only if the reinforcement criterion and the measure of the effect of differential reinforcement are both defined on the same response property. Because the cited studies of operant variability defined their reinforcement criterion on a sequence property P and measured the effect of differential reinforcement on another sequence property P′, their results cannot provide direct evidence that an operant relation was established.