In problem-based learning, the development of self-directed learning skills is encouraged through confronting students with (professional) problems. However, several other elements of a problem-based curriculum, such as general teaching objectives, lectures and tutors, may have an impact on students' actual learning activities. The present study focuses on the extent to which various elements of a problem-based curriculum influence students' decisions on what to study. First, interviews were conducted to obtain qualitative data about what actually takes place when students initiate learning activities during self-study. Based on the findings of these interviews, a questionnaire was developed, consisting of statements describing elements of the learning process and their influence on student learning. Elements included in the questionnaire were: the discussion in the tutorial group, content tested, course objectives, lectures, the tutor and reference literature. The students reported that all these elements may have an impact on decisions on what to study. Moreover, first-year students tend to rely more on the literature cited in the references list and content covered in lectures and tests than students in the other three curriculum years. In general, the influence of these elements showed a decrease over the four curriculum years. The influence of the discussion in the tutorial group, on the contrary, tended to increase over the four curriculum years. These findings suggest that students in a problem-based curriculum become more accomplished self-directed learners over the four curriculum years, even although they are provided with many clues which may play a role in their decisions on what to study.