Instrumental behavior in humans is sensitive to the correlation between response rate and reward rate

Recent theories of instrumental conditioning postulate that the correlation between responses and outcome rates is a critical factor in instrumental free-operant performance and goal-directed control. However, it is still not clear whether human performance can be sensitive to such variable. Using a novel within-subject design, participants were trained under ratio and interval contingencies of reinforcement matching both outcome probability and outcome rates. The impact of rate correlation on performance was evident in the higher performance observed under ratio contingencies for both types of matching. Moreover, there was no difference in performance between two classes of interval schedules with similar correlational properties but different reward probabilities. The result discussed in terms of a recent dual-system model of instrumental behavior.