Virtually any sustained, effortful activity can be motivated by factors internal to the activity (e.g., scientists pursuing discoveries) or instrumental to it (e.g., scientists pursuing promotions or status). Research in economics and psychology suggests that instrumental motives (often called “extrinsic motives”) undermine the positive impact of internal motives (often called “intrinsic motives”). However, despite 40 y of research, mostly using laboratory-based manipulations, the effect of instrumental motives on the impact of internal motives remains controversial, and naturalistic, long-term tests of its existence are lacking. We show that holding both internal and instrumental motives for attending West Point harms outcomes associated with persistence and performance quality in a sample of over 10,000 cadets over periods spanning up to 14 y.
Although people often assume that multiple motives for doing something will be more powerful and effective than a single motive, research suggests that different types of motives for the same action sometimes compete. More specifically, research suggests that instrumental motives, which are extrinsic to the activities at hand, can weaken internal motives, which are intrinsic to the activities at hand. We tested whether holding both instrumental and internal motives yields negative outcomes in a field context in which various motives occur naturally and long-term educational and career outcomes are at stake. We assessed the impact of the motives of over 10,000 West Point cadets over the period of a decade on whether they would become commissioned officers, extend their officer service beyond the minimum required period, and be selected for early career promotions. For each outcome, motivation internal to military service itself predicted positive outcomes; a relationship that was negatively affected when instrumental motives were also in evidence. These results suggest that holding multiple motives damages persistence and performance in educational and occupational contexts over long periods of time.