The following article by Barba (2012a) addresses Neuringer's proposal that variability is an operant dimension of behavior, that is, that variability can be reinforced, extinguished, and brought under stimulus control, just like any other response property. Barba confines his argument to methodological considerations: He points out that the…

In a previous issue of "The Behavior Analyst," the authors discussed the ambiguities that surround the distinction between positive and negative reinforcement. Seven distinguished behavior analysts commented on their article. The authors believe that this dialogue represented a constructive step toward clarification of an important concept within…