BEHAVIORAL VARIABILITY IS CONTROLLED BY DISCRIMINATIVE STIMULI

Previous research has demonstrated that behavioral variability can be modified by reinforcers contingent on it, but there has been no convin cing evidence of discriminative stimulus control over such variability . We therefore rewarded 20 rats for variable response sequences in the presence of one stimulus and provided equal rewards independently of sequence variability in the presence of a second stimulus. We found th at sequence variability was significantly higher during the first stim ulus than during the second, with the greatest difference occurring im mediately following onset of the stimuli. Removing the discriminative stimuli caused levels of variability to converge. These experiments pr ovide strong evidence that behavioral variability can be controlled by discriminative stimuli, which may be important for general theories o f operant behavior and their applications.