Can learners play a role in their assessment?

Yes learners can play the role to assessment his or her performance.

It is really vital to include learners in their assessment, as some schools and some approaches to education like Reggio Emilia and Te Whariki curriculum do that.
This has shown many benefits for both the teacher and learner, for example, it leads to motivation for life-long learning for both due to the dialogue that goes between teacher-learner and the reflection that they do together.