Abstract

Two experiments evaluated history effects on induced and operant variability. College students typed
three-digit sequences on a computer keyboard. Sequence variability was induced (by no reinforcement or
variation- independent reinforcement) or reinforced (by variation- or repetition-dependent reinforcement).
Conditions with induced and operant variability were presented according to a reverse between-groups de-
sign. In Experiment 1, we examined transitions from the variation or repetition contingencies to no reinforce-
ment, and vice versa. In Experiment 2, the variation or repetition contingencies were followed or preceded
by variation-independent reinforcement. The results showed that (1) a history of no reinforcement impaired
operant variability learning; (2) induced variability levels were higher and lower after a history of reinforce-
ment for variation and repetition, respectively; (3) repetition was more easily disrupted by no reinforcement
and independent reinforcement than was variation; and (4) response variability and stability were a function
of past and current reinforcement conditions. These results indicate that reinforcement history influences both
induced and operant variability levels