The author of this article proposes that students will be more motivated to learn, not just perform well, if giving more choice in the assessment process (see quotes below).
Education theorists sometimes distinguish between two orientations that students take toward learning: mastery or performance. Performance-oriented learners want to do well on tests, essays, or other assessments. Mastery-oriented learners want to grasp the material for its own sake, because they find it interesting, relevant, or beautiful. Plenty of research suggests that a mastery orientation creates deeper and longer learning.
That same research suggests that we can help orient students toward mastery by giving them choices. As biologist James Zull has written in The Art of Changing the Brain, “one important rule for helping people learn is to help the learner feel she is in control.” Likewise, the authors of How Learning Works: 7 Research-Based Principles for Smart Teaching, argue that mastery arises when we “allow students to choose among options and make choices that are consistent with their goals and the activities that they value.”