In a context of learning, visualization of learners’ processes and states can provide an intuitive understanding of learning processes and learning states. As a result, learners and teachers are able to take appropriate steps to improve learning. Physiological data such as electrodermal activity and cardiac response are adopted as a non-invasive method to detect stress and emotion, providing awareness and feedback to learners. However, there is little research on sensor data visualization considering human-computer interfaces and user experience. This paper summarizes the state of emotion visualization in a learning context and discusses limitations of previous studies on learners’ experience. Design considerations based on emotion visualization are compared to design principles for user interfaces and user experience, which shows the shortcomings of current approaches to emotion visualization. We show the importance of combining design and learning considerations for emotion visualization and intervention. The paper concludes with remarks on future work.