Robots and virtual agents need to adapt existing and learn novel behavior to function autonomously in our society. Robot learning is often in interaction with or in the vicinity of humans. As a result the learning process needs to be transparent to humans. Reinforcement Learning (RL) has been used successfully for robot task learning. However, this learning process is often not transparent to the users. This results in a lack of understanding of what the robot is trying to do and why. The lack of transparency will directly impact robot learning. The expression of emotion is used by humans and other animals to signal information about the internal state of the individual in a language-independent, and even species-independent way, also during learning and exploration. In this article we argue that simulation and subsequent expression of emotion should be used to make the learning process of robots more transparent. We propose that the TDRL Theory of Emotion gives sufficient structure on how to develop such an emotionally expressive learning robot. Finally, we argue that next to such a generic model of RL-based emotion simulation we need personalized emotion interpretation for robots to better cope with individual expressive differences of users.

Engagement is a concept of the utmost importance in human-computer interaction, not only for informing the design and implementation of interfaces, but also for enabling more sophisticated interfaces capable of adapting to users. While the notion of engagement is actively being studied in a diverse set of domains, the term has been used to refer to a number of related, but different concepts. In fact it has been referred to across different disciplines under different names and with different connotations in mind. Therefore, it can be quite difficult to understand what the meaning of engagement is and how one study relates to another one accordingly. Engagement has been studied not only in human-human, but also in human-agent interactions i.e., interactions with physical robots and embodied virtual agents. In this overview article we focus on different factors involved in engagement studies, distinguishing especially between those studies that address task and social engagement, involve children and adults, are conducted in a lab or aimed for long term interaction. We also present models for detecting engagement and for generating multimodal behaviors to show engagement.

In this article, a team of authors from the Geeks and Groupies workshop, in Leiden, the Netherlands, compare prototypical approaches to studying group interaction in social science and computer science disciplines, which we call workflows. To help social and computer science scholars understand and manage these differences, we organize workflow into three major stages: research design, data collection, and analysis. For each stage, we offer a brief overview on how scholars from each discipline work. We then compare those approaches and identify potential synergies and challenges. We conclude our article by discussing potential directions for more integrated and mutually beneficial collaboration that go beyond the producer–consumer model.