From experimental music technology to clinical tool Alexander Refsum Jensenius Abstract Human body motion is integral to all parts of musical experience, from performance to perception. But how is it possible to study body motion in a systematic manner? This article presents a set of video-based visualisation techniques developed for the analysis of music-related body motion, including motion images, motion-history images and motiongrams. It includes examples of how these techniques have been used in studies of music and dance performances, and how they, quite unexpectedly, have become useful in laboratory experiments on ADHD and clinical studies of CP. Finally, it includes reflections regarding what music researchers can contribute to the study of human motion and behaviour in general. Introduction In the early 2000s, I started experimenting with live video in interactive music/dance performances. At that time, laptop computers were barely fast enough to handle the simple manipulation of live video feeds and were nowhere near the advanced realtime analysis that is possible today. Never would I have imagined that the video analysis tools I originally developed for these experimental music performances would be tested in clinical practice at hospitals on three continents a decade later. In this article, I will tell the story about how my software moved from the stage to the hospital, how this has shaped its related methods and tools, and how the experience has helped me as a music researcher and as a research musician. It was during my PhD research on music-related body motion that the Musical Gestures Toolbox came to life (Jensenius et al. 2005; Jensenius 2007). The main goal of my research at this stage was to understand more about the body motion of both performers (such as musicians and dancers) and perceivers (people experiencing music), and specifically about the ways in which such motion was related to the sound of the music to which they moved or which they created. The human body has always been integral to all aspects of musicking, from performance to perception. The concept of 1