Journal of the experimental analysis of behavior
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Five pigeons were trained on concurrent variable-interval schedules in a switching-key procedure. The overall rate of reinforcement was constant in all conditions, and the ratios of reinforcers obtainable on the two alternatives were varied over seven levels. Each condition remained in effect for 65 sessions, and the last 50 sessions of data from each condition were analyzed. ⋯ A longer term effect of reinforcement was also evident, which changed as a function of the reinforcer ratio arranged. More local analyses showed regularities at a reinforcer-by-reinforcer level and large transient movements in preference toward the just-reinforced alternative immediately following reinforcers, followed by a return to stable levels that were related to the reinforcer ratio in effect. The present data suggest that the variables that control choice have both short- and long-term effects and that the short-term effects increased when the reinforcer ratios arranged were more extreme.