Commit to Change, or Change Your Commitment? Dynamic Demand for Goal Difficulty

In two studies—an online experiment using a real effort task and a field study of weight loss among Weight Watchers members—we investigate how demand for difficult goals changes over time in the presence or absence of goal-contingent incentives. To facilitate motivation and self-control in an effortful task, people may choose aggressive goals. However, because individuals in incentive conditions only earn bonus payments when they achieve their goals, they simultaneously have an economic incentive to select (and potentially modify over time) performance and weight loss targets that can be easily reached.

In Study 1, we recruited online workers to complete three trials of a computerized effort task and asked them to set performance goals for each trial. Some workers were offered bonus incentives that were contingent upon goal achievement, thus allowing these participants to ensure incentive collection by choosing an easy goal or to put their incentive at risk by selecting a difficult goal. Other workers were offered equivalently-sized incentives that were independent from goal achievement, whereas yet other workers received no bonus incentives. We found that the provision of goal-contingent incentives reduced demand for difficult goals relative to conditions in which no incentives were offered or in which incentives were not contingent upon goal achievement. That is, people behaved rationally in selecting goals when incentives were made contingent upon goal achievement in a context where participants likely had little intrinsic motivation regarding the task itself (a typing task). These differences in goal selection among the conditions persisted over multiple trials, even as participants selected more difficult goals on later trials overall.

In Study 2, we partnered with Weight Watchers to conduct a field experiment and to determine how contingent incentives influence the selection of weight goals over a six-month period. 191 Weight Watchers members were randomly assigned to either a control condition of daily weigh-ins and daily feedback, or to an incentive condition with daily weigh-ins, daily feedback, and a daily financial incentive of $2.80 for meeting a weight loss goal. Participants selected weight loss goals each month. Despite having an economic incentive to choose the most modest goal possible, nearly 90% of incentivized participants picked an initial goal that was more challenging than the minimum needed. However, as people gained experience with goal-setting procedures and their own patterns of weight change over time, those offered monetary incentives were more likely to shift to less aggressive goals.

Across both studies, we find substantial initial demand for goals that are more ambitious than strictly required, regardless of incentive provision. In the absence of goal-contingent incentives, this demand for difficult goals remains high over time. However, when considering commitment devices in which monetary gains are foregone if goals are not met, people are responsive to the likelihood of goal achievement and demonstrate dynamic demand over iterated trials.