Howard Rachlin and Leonard Green examined how pigeons choose between immediate and delayed rewards, finding that their preference shifts with the delay (T) between choices. When given a choice between an immediate small reward and a delayed large one, pigeons usually prefer the immediate reward. However, when faced with a choice between a short delay followed by the immediate reward or a longer delay followed by the large reward, their preference depends on T. As T increases, pigeons increasingly prefer the larger delayed reward, reflecting a form of self-control. This reversal of preference is predicted by several models of reward choice. Commitment to a course of action is a form of self-control, as seen in examples like payroll savings, where individuals commit to saving a portion of their paycheck, even though they might prefer to spend it. This commitment is based on a reversal of preference over time. Similarly, a device developed by Azrin and Powell limits chain smoking by locking a cigarette case for 2 hours after it is closed, making the next cigarette less valuable until the first one is smoked. Commitment, as seen in these examples, is an active process of self-control. However, it can also be viewed as a simple choice between currently more valuable alternatives. The decision to commit is based on the expected reversal of preference over time. The matching law, which predicts that the ratio of values of two rewards is the product of the ratio of amounts and the inverse ratio of delays, explains these reversals. In an experiment, pigeons were exposed to contingencies similar to those described, with varying delays (T) between choices. The results showed that as T increased, pigeons increasingly preferred the larger delayed reward, consistent with the matching law. The experiment demonstrated that commitment involves a reversal of preference over time, and that this reversal is predicted by simple models of reward choice. The findings suggest that self-control and commitment are closely related, with commitment being a form of self-control that involves reversing preferences over time. The study highlights the importance of understanding how preferences change over time in the context of delayed rewards and the role of commitment in self-control.Howard Rachlin and Leonard Green examined how pigeons choose between immediate and delayed rewards, finding that their preference shifts with the delay (T) between choices. When given a choice between an immediate small reward and a delayed large one, pigeons usually prefer the immediate reward. However, when faced with a choice between a short delay followed by the immediate reward or a longer delay followed by the large reward, their preference depends on T. As T increases, pigeons increasingly prefer the larger delayed reward, reflecting a form of self-control. This reversal of preference is predicted by several models of reward choice. Commitment to a course of action is a form of self-control, as seen in examples like payroll savings, where individuals commit to saving a portion of their paycheck, even though they might prefer to spend it. This commitment is based on a reversal of preference over time. Similarly, a device developed by Azrin and Powell limits chain smoking by locking a cigarette case for 2 hours after it is closed, making the next cigarette less valuable until the first one is smoked. Commitment, as seen in these examples, is an active process of self-control. However, it can also be viewed as a simple choice between currently more valuable alternatives. The decision to commit is based on the expected reversal of preference over time. The matching law, which predicts that the ratio of values of two rewards is the product of the ratio of amounts and the inverse ratio of delays, explains these reversals. In an experiment, pigeons were exposed to contingencies similar to those described, with varying delays (T) between choices. The results showed that as T increased, pigeons increasingly preferred the larger delayed reward, consistent with the matching law. The experiment demonstrated that commitment involves a reversal of preference over time, and that this reversal is predicted by simple models of reward choice. The findings suggest that self-control and commitment are closely related, with commitment being a form of self-control that involves reversing preferences over time. The study highlights the importance of understanding how preferences change over time in the context of delayed rewards and the role of commitment in self-control.