Designing and evaluating the affectivity of the robot body has become a frontier topic in Human-Robot Interaction (HRI), with previous studies emphasizing the importance of robot embodiment for human-robot communication. In particular, there is growing interest in how the tactile, haptic materiality of the robot influences and mediates users’ affective and emotional states. Indeed, the sheer physicality of robotic systems is a crucial factor in the morphology of the robotic platform, and therefore in the robot's appearance to the user. How do the tactile properties of materials subtly influence user interaction? Why do certain morphologies prompt more empathetic interactions than others? How is nonverbal communication affected through the coordination of movements of the torso, head, and appendages to provide more naturalistic-seeming interaction? What is the role of nonverbal communication in the production of artificial empathy? And how do such factors encourage trust and foster confidence for nonexpert users to interact in the first place? This recognition of machinic corporeality has been of practical interest to designers and engineers working across a range of robot forms and functions.

The objective of this special issue is to further this discussion, to consider theoretical, ethical, empirical, and methodological questions related to the design of robotic bodies in the context of affective HRI, and thus foster cross currents among engineering, design, social science, and artistic communities. It originally emerged as a set of conceptual and practical questions from a workshop at the 2020 ACM/IEEE International Conference on Human-Robot Interaction (HRI’20) in Cambridge, UK, co-organized by two of the editors [3]. The workshop, like so many other events, was canceled because of the restrictions of the COVID-19 pandemic. Consequently, we tried to pursue a longer-term exchange of engineering, design, and conceptual considerations through the publication of this special issue. Building out from the more practically minded exchanges of an in-person workshop, here was an opportunity to invite more wide-ranging contributions to consider questions related to the design of robotic bodies in the context of affective HRI. The issue could thus explore topics bridging embodiment and affect, including touch, materials, and physical form from the points of view of artists, designers, engineers, and social scientists alike.