"I'll have one of each": how separating rewards into (meaningless) categories increases motivation.

We propose that separating rewards into categories can increase motivation, even when those categories are meaningless. Across six experiments, people were more motivated to obtain one reward from one category and another reward from another category than they were to obtain two rewards from a pool that included all items from either reward category. As a result, they worked longer when potential rewards for their work were separated into meaningless categories. This categorization effect persisted regardless of whether the rewards were presented using a gain or loss frame. Using both moderation and mediation analyses, we found that categorizing rewards had these positive effects on motivation by increasing the degree to which people felt they would "miss out" if they did not obtain the second reward. We discuss implications for research on motivation and incentives.