Expressivity in Interaction: a Framework for Design

Expressivity is frequently recurring as a term in HCI, but it is often approached from different perspectives. Affective computing prompted research into emotional expressivity, and with technology becoming more ubiquitous and tangible, the opportunities for expressive behaviors towards systems as well as the expressivity of systems increases. By analyzing exemplar research-through-design cases and a literature survey on the use of expressivity in interaction, we discuss how different perspectives and concepts contribute to understand expressivity in interaction. We integrate these perspectives and make them operational for interaction design by creating a framework including design considerations such as freedom of interaction, action-perception loops, multimodality, subtlety, ambiguity, skill development and temporal form. The framework is a result of a mixed-method approach including a review of existing definitions and scholarly artefacts, and a systematic literature review to identify design cases including an analysis of these design cases. We finally illustrate how the framework has been used to inform the design of a shape-changing soft-robotic interface. As a result, we contribute an integrated framework on how to design for expressivity in interaction.