Evaluation of Rapport in Human-Agent Interactions with a VR Trainer after a 6-week Exergame Training for Senior Users with Hypertension.
Authors: Buchem Ilona , Stamm Oskar , Vorwerg Susan , Kruschel Kai , Hildebrand Kristain 
Published: June 2022

Human interactions with the trainer during physical training can be highly engaging and motivating [1] and are based on rapport as a dynamic structure of mutual attentiveness and coordination [2]. Human-Agent interaction in virtual reality (VR) aims to establish interaction patterns and rapport with virtual agents similar to real life. Research shows that users react towards virtual agents similar to real people [3] and that rapport is established similar to human rapport [4]. Therefore, rapport with virtual trainers in exergames is used to enhance an engaging and motivating user experience.In this paper we report on the results from an evaluation study on perceptions and interactions with the virtual trainer “Anna” after a 6-week exergame training for senior patients with hypertension. The human-like “Anna” is the key element of interaction design in a gamified series of exergames developed in the bewARe project. Anna was developed as a realistic, full body, female figure (silhouette) to motivate participation in the VR training. The primary goal of our research was to evaluate to what extent senior users can establish rapport with the virtual trainer as a factor contributing to positive user experience and training outcomes. The evaluation was conducted with 23 participants aged 65 and older with diagnosed hypertension. The virtual trainer Anna facilitated user participation in both exergames by giving instructions, modeling movements and providing feedback during the exergames in the HTC Vive Pro Headset. We used the 15-item rapport scale by [5] to measure rapport. The study also applied further research instruments to explore perceptions of the virtual trainer such as the trait list with 9 items describing selected features of the virtual trainer, and the bipolar uncanniness questionnaire with 40 adjectives used to assess possible Uncanny Valley effects described by [6]. The results of the rapport scale indicate that the design of the virtual trainer was effective for establishing rapport especially in terms of building a relationship with the virtual trainer and enhancing the engagement of senior users to participate in the VR training. However, the design was less effective in creating a positive perception of the trainer as a warm, caring and respectful agent. The overall median of the rapport scale was 6 (Min:1,Max:8). The results of the evaluation of the trait list revealed that voice quality, speech pauses and bodily movements were rated highest, followed by head and hand movements. The lowest values were researched for face expression. In the Uncanny Valley questionnaire, the median value for the humannes scale was 1 (Min:-3,Max:3), for the attractiveness 1 (Min:0,Max:3) and for the eeriness 0 (Min:-1,Max:0). Furthermore, the paper explores the relationships between the rapport scores and the perception of senior trainees of selected characteristics of the virtual agent and the uncanniness scale. Finally, given the diverse results from the study, the paper discusses possible design options for enhanced rapport and motivational effects of a virtual trainer based on the analysis of literature in related areas.References1. Ghosh, P., Satyawadi, R., Prasad Joshi, J., Ranjan, R. & Singh, P.: Towards more effective training programmes: a study of trainer attributes, In: Industrial and Commercial Training, vol. 44, pp. 194-202 (2012).2. Tickle-Degnen, L. & Rosenthal, R.: The Nature of Rapport and Its Nonverbal Correlates. In: Psychological Inquiry, vol. 1, pp. 285-293 (1990).3. Garau, M., Slater, M., Pertaub, D. P. & Razzaque, S. The responses of people to virtual humans in an immersive virtual environment. Presence. 14, pp. 104–116 (2005).4. Huang, L., Morency, L., & Gratch, J.: Virtual Rapport 2.0. In: Vilhjálmsson H. H., Kopp S., Marsella S., Thórisson K.R. (eds.) Intelligent Virtual Agents. IVA 2011. Lecture Notes in Computer Science, vol. 6895, pp. 68--79. Springer, Berlin, Heidelberg (2011).5. Gratch J., Wang N., Gerten J., Fast E. & Duffy R.: Creating Rapport with Virtual Agents. In: Pelachaud C., Martin JC., André E., Chollet G., Karpouzis K., Pelé D. (eds) Intelligent Virtual Agents. IVA 2007. Lecture Notes in Computer Science, vol 4722. Springer, Berlin, Heidelberg, (2007).6. Ho, C., & MacDorman, K.F.: Revisiting the uncanny valley theory: Developing and validating an alternative to the Godspeed indices. Comput. Hum. Behav., 26, pp. 1508-1518 (2010).