Over the last decades, references to multimedia have become ubiquitous and present it as a tremendous technology. Today, when reflecting upon computer-based learning material, animation is definitively an educational resource that should be considered. This thesis addresses two issues: the effectiveness of multimedia animations towards comprehension in comparison to static graphics and how animations could support learning three-dimensional information. Additionally, the present work examines the intricate interplay between animation, learners' individual spatial abilities, and instructional design factors in the context of learning anatomy. A meta-analysis and two experimental studies have been set up to meet these challenges. The meta-analysis summarizes quantitatively the results of 55 experiments in order to assess whether animated displays are more conducive to learning compared to static graphics, and to which learning goals they would apply. The global results revealed a small but beneficial effect of animations as compared to static graphics for learning dynamic systems. Most of the experiments included in the meta-analysis dealt with conceptual knowledge. In many instructional domains, including mechanics and biology, animation is often used to learn three-dimensional information. However this function of the animation is rarely considered in the field of multimedia learning. Thus, two experimental studies were conducted and investigated the impact of animated visualization on learning 3D objects in the field of anatomy. The first experimental study investigated the animation effectiveness in learning functional anatomy with 3D rotating models of the structure and its movement by comparing animated versus static displays. The second experimental study investigated whether providing different types of orientation references, either internal embedded axes or an external avatar, could support the building of mental representations of 3D structures and improve subsequent judgment performance. Altogether, the meta-analysis and the two experimental studies conducted in this thesis provided new insights into the benefits of using animations in instructional materials. This work contributed to the understanding of how animation may support learning anatomy and the building of mental representations of 3D objects.