We investigated students' knowledge and beliefs about the impact of using three-dimensional (3D) multimedia presentations. Students listened to a lecture about the ventricular system, which was presented alone (Experiment 1 only) or with a 3D or a 2D video illustrating the system. Afterwards, students judged how well they would perform on a criterion test. In Experiment 1, students judged that the 3D presentation would be superior to listening to the lecture alone (d = 0.81). Mean judgments were higher for the 3D than 2D presentation (d = 0.24), but this difference was not significant, so we estimated the effect size again. In Experiment 2, judgments were significantly higher after the 3D than 2D presentations (d = 0.40). Test performance was not significantly greater after the 3D than 2D presentations. A survey study again revealed that students believe 3D presentations are superior, and most students reported preferring them to 2D presentations.