When do diagrams enhance learning? A framework for designing relevant representations

Although many studies demonstrate large learning gains when instruction includes diagrams, diagrams do not always lead to improved outcomes. How can instructional designers know whether a given diagram will enhance learning? We have developed a framework of three factors that influence the effectiveness of a diagram in a particular learning situation: the learning objective, the design of the visual representation and the cognitive processing of the learner. In a randomized-design study conducted in a college chemistry class, we found that instruction that included diagrams created with this framework led to enhanced performance on open-ended transfer items compared to traditional instruction, particularly for low-performing students. We propose that a concept-based cognitive theory of multimedia learning that includes a conceptual working memory component may explain why the efficacy of diagrams depends heavily on the prior knowledge of the learner as well as the conceptual information available in the representation.