Understanding Gesture Expressivity through Muscle Sensing

Expressivity is a visceral capacity of the human body. To understand what makes a gesture expressive, we need to consider not only its spatial placement and orientation, but also its dynamics and the mechanisms enacting them. We start by defining gesture and gesture expressivity, and then present fundamental aspects of muscle activity and ways to capture information through electromyography (EMG) and mechanomyography (MMG). We present pilot studies that inspect the ability of users to control spatial and temporal variations of 2D shapes and that use muscle sensing to assess expressive information in gesture execution beyond space and time. This leads us to the design of a study that explores the notion of gesture power in terms of control and sensing. Results give insights to interaction designers to go beyond simplistic gestural interaction, towards the design of interactions that draw upon nuances of expressive gesture.