In an experiment, we tested whether anthropomorphism would reduce psychological stress associated with human-robot interactions (HRI). Participants anticipated (vs. did not anticipate) an interaction with a humanlike versus machinelike robot type, and their electrodermal activity (EDA), a physiological indicator of psychological stress, was measured. Results indicate that anticipating an HRI increased psychological stress independent of robot type.

The topic of motivation is a crucial issue for various human-robot interaction (HRI) scenarios. Interactional aspects of motivation can be studied in human-human interaction (HHI) and build the basis for modeling a robot's interactional conduct. Using an ethnographic approach we explored the factors relevant in the formation of motivation-relevant processes in an indoor-cycling activity. We propose an interactive, action-based motivation model for HRI that has been implemented in an autonomous robot system and tested during a long-term HRI study. The model is based on micro-analyses of human indoor cycling courses and resulted in an adaption of specific dialog patterns for HRI. A qualitative evaluation - accompanied by a quantitative analysis - demonstrated that the transfer of interaction patterns from HHI to HRI was successful with participants benefitting from the interaction experience (e.g., performance, subjective feeling of being motivated).

We present the design process, realization and evaluation of a robot system for nteractive object learning. The system-oriented evaluation, in particular, addresses an open problem for the evaluation of systems, where overall user satisfaction depends not only on the performance of the parts, but also on their combination, and on user behavior. Based on the PARADISE method known from spoken dialog systems, we have defined and applied internal and external metrics for fine-grained and largely automatable identification of such relationships. Through evaluation with n=28 subjects, indicator functions explaining up to 55% of variation in several satisfaction metrics were found. Furthermore, we demonstrate that the system's interaction style reduces the need for instruction and successfully recovers partial failures.

Regarding the future usage of social robots in workplace scenarios, we addressed the question of potential mere robotic presence effects on human performance. Applying the experimental social facilitation paradigm in social robotics, we compared task performance of 106 participants on easy and complex cognitive and motoric tasks across three presence groups (alone vs. human present vs. robot present). Results revealed significant evidence for the predicted social facilitation effects for both human and robotic presence compared to an alone condition. Implications of these findings are discussed with regard to the consideration of the interaction of robotic presence and task difficulty in modeling robotic assistance systems.

Users draw on four sources to judge a robot's competence: (1) the robot's voice, (2) physical appearance of and (3) the interaction experience with the robot but also (4) the relationship between the robot's physical appearance and its conduct. Furthermore, most approaches in social robotics have an outcome-oriented focus and thus use questionnaires to measure a global evaluation of the robot after interaction took place. The present research takes a process-oriented approach to explore the factors relevant in the formation of users' attitudes toward the robot. To do so, an ethnographic approach (Conversation Analysis) was employed to analyze the micro-coordination between user and robot. We report initial findings from a study in which a robot took the role of a fitness instructor. Our results emphasize that the participant judges step-by-step the robot's capabilities and differentiates its competence on two levels regarding to the robot's role: a robot as a (1) social/interactional co-participant and as a (2) fitness instructor.