Evolutionary theory hypothesises that specific expressive behaviours were selected over the course of human evolution because they had adaptive value in social relationships. This hypothesis suggest that the evolution and future of affective computing is, indeed, an ongoing wondrous journey where machines (computers) meet humans, and where key issues and themes of affective communication, such as context, emotion colouring, multimodality, back-channelling, intensity, duration, continuity, and sustainability, evolve over the course of time, and over the course of that encounter. The authors and readers of this book thus become a part of this wondrous journey.
– Hatice Gunes, Imperial College London, UK and University of Technology Sydney, Australia