Introduction to the affect-based human behavior understanding special issue

Computer analysis of human behavior has been receiving a lot of attention in the past few years. The main drive behind this interest is the widespread penetration of computer-based systems and Internet applications that increasingly enter the domain of social relations. This requires more responsive systems, capable of adapting to the rich behavior patterns exhibited by interacting humans. The present special issue grew out of the First International Workshop on Human Behavior Understanding (HBU'10, held as a satellite to ICPR 2010), which demonstrated that two major areas of present research focus in this domain were activity recognition and affect sensing. This special issue deals with the latter. The editors received 17 submissions to this special issue, and only a few were extended papers from the original workshop. The applications tackled in this set of papers covered a broad area, dealing with human-human interactions (including interviews, meetings, social gatherings, and social games), human-virtual agent interactions (for application interfaces, as well as for tutoring and coaching scenarios), and improved multimedia applications. The affective content was analyzed by visual inspection of facial cues, evaluation of affective gestures, nonverbal speech and voice cues, timing of interactions, proximity and body language of interacting parties, and physiological signals. The four selected papers in this issue represent the spectrum of affect-based human behavior analysis very well, in the variety of their settings, as well as in the modalities they consider.