Behavior and usability analysis for multimodal user interfaces

Multimodal interfaces offer ever-changing tasks and challenges for designers to accommodate newer technologies, and as these technologies become more accessible, newer application scenarios emerge. Prototype development and user evaluation are important steps in the creation of solutions to these challenges. Furthermore, playful interactions and games are shown to be important settings to study social signals of interaction people. Research in multimodal analysis brings together people with diverse skills and specializations on the integration of tools in different modalities, to collect and annotate data, and to exchange ideas and skills, and this special issue is a reflection of that collective effort.