Learning to vary and varying to learn.

We compared two sources of behavior variability: decreased levels of reinforcement and reinforcement contingent on variability itself. In Experiment 1, four groups of rats were reinforced for different levels of response-sequence variability: one group was reinforced for low variability, two groups were reinforced for intermediate levels, and one group was reinforced for very high variability. All of the groups experienced three different reinforcement frequencies for meeting their respective variability contingencies. Results showed that reinforcement contingencies controlled response variability more than did reinforcement frequencies. Experiment 2 showed that only those animals concurrently reinforced for high variability acquired a difficult-to-learn sequence; animals reinforced for low variability learned little or not at all. Variability was therefore controlled mainly by reinforcement contingencies, and learning increased as a function of levels of baseline variability. Knowledge of these relationships may be helpful to those who attempt to condition operant responses.