In conservation projects in and around protected areas (PAs), a suite of policy instruments are used to promote conservation behavior in local people. Few studies have related psychological research on motivational values to conservation in PAs. We conducted a systematic review of 120 peer-reviewed articles to assess the relative frequencies of policy instruments that aimed to foster intrinsic versus extrinsic motivations to conserve. We examined how the type of motivation engendered by the instrument (i.e., intrinsic or extrinsic motivation and based on the description of how the project was designed and implemented) influenced the ecological, economic, and social success of the project. We assessed the success of the project in only the case studies that included a quantitative or qualitative analysis of success. Projects designed to foster at least one intrinsically motivating instrument were 3 times more likely to meet socioeconomic or ecological goals. Although certain types of instruments such as payments or fines tended to be based on extrinsic motivators more often than education or monitoring programs, several successful projects involving payments or fines were linked to intrinsic motivation in the local community. Thus, our results suggest that rather than debating the relative merits of specific types of policy instruments, conservationists may have more success by focusing on how different motivators, suited to specific contexts, can better empower local communities to conserve. Broadly, our results suggest the current emphasis on social justice and well-being of local communities is a positive step toward protecting the world's remaining biodiversity.
