This work constitutes a contribution to the emergence of a common writing for French Sign Language in a graphical or even a typographical framework. In this article we present ThirdEye, an interactive visualisation tool designed for movement analysis. As a research tool, ThirdEye’s main objective is to help study the importance of movement in the production of meaning within the context of sign language. In this paper, we will show why and how this device was conceived and how it can help to shed light on the relationships between sign language and writing.