Experimental analysis of variability in operant behavior

Variability is not necessarily a fixed property of behavior, as implied by the term inherent variability, but can be considered a dependent variable amenable to analysis and control. Experiments demonstrate that behavioral variability can both be expanded and contracted. Expansion of variability is needed for shaping where experimental methods select for “novelty” among the variations in behavior. Contraction of variability happens when the same contingency applies for a long time and each response becomes very efficient and varies very little from one episode to the next. Experiments will illustrate these issues. In one experiment with rats, initial expansion and then gradual contraction of variability is shown within a session during acquisition of “complex” operants. In a second experiment, expansion and contraction of variability are brought under stimulus control. These experimental paradigms are useful for studies of variability in behavioral repertoires.