Human or robot? Exploring different avatar appearances to increase perceived security in shared automated vehicles

Journal on Multimodal User Interfaces (2024) 18:209–228 https://doi.org/10.1007/s12193-024-00436-x ORIGINAL PAPER Human or robot? Exploring different avatar appearances to increase perceived security in shared automated vehicles Martina Schuß1 · Luca Pizzoni1 · Andreas Riener1 Received: 31 January 2024 / Accepted: 21 July 2024 / Published online: 30 August 2024 © The Author(s) 2024 Abstract Shared Automated Vehicles (SAVs) promise to make automated mobility accessible to a wide range of people while reducing air pollution and improving traffic flow. In the future, these vehicles will operate with no human driver on board, which poses several challenges that might differ depending on the cultural context and make one-fits-all solutions demanding. A promising substitute for the driver could be Digital Companions (DCs), i.e. conversational agents presented on a screen inside the vehicles. We conducted interviews with Colombian participants and workshops with German and Korean participants and derived two design concepts of DCs as an alternative for the human driver on SAVs: a human-like and a robot-like. We compared these two concepts to a baseline without companion using a scenario-based online questionnaire with participants from Colombia (N = 57), Germany (N = 50), and Korea (N = 29) measuring anxiety, security, trust, risk, control, threat, and user experience. In comparison with the baseline, both DCs are statistically significantly perceived as more positively. While we found a preference for the human-like DC among all participants, this preference is higher among Colombians while Koreans show the highest openness towards the robot-like DC. Keywords Cross-cultural study · Conversational agent · Digital companion · Shared automated vehicles · Perceived security 1 Introduction The era of automated vehicles (AVs) is upon us, promising to revolutionize our mobility and transform the in-vehicle experience fundamentally. These vehicles, capable of automated operation through environmental sensing and responsive actions, hold the promise of reshaping transportation dynamics [1–3]. Among these innovations, shared automated vehicles (SAVs), employing AVs in a collective framework, emerge as an economically viable option, potentially making travel more affordable while curbing congestion, emissions, and the land footprint of parking spaces through higher capacity utilization in comparison to privately used vehicles [4, 5]. However, despite their manifold advantages, challenges persist, particularly regarding the absence of a human driver [6–8]– a source for a sense of security [9]. While current SAVs operate with onboard operators–at least in Europe– due to legal constraints, the future land- B 1 Martina Schuß scape envisions fully automated SAVs for public use. Yet, the acceptance of these vehicles may hinge on addressing the perceived insecurity stemming from the lack of a human driver. To bridge this gap, Schuß et al. [10] suggest a Conversational Agent (CA) functioning as a Digital Companion (DC) to emulate certain driver functions, although specifics remain open. Recognizing the cultural diversity in perceptions of automation trust and security needs, our study, rooted in a German institution, delves into contrasting cultural landscapes. We aim to explore how different countries, delineated by the Hofstede framework [11] and varying perceptions of security in public transportation (PT) systems, shape users’ views on SAV security needs and their expectations from a DC. Germany, statistically exhibiting high personal security in PT but lower perceived security [12], stands in contrast to South Korea, where extensive CCTV coverage creates a perceived high security in PT [12–14]. Additionally, we incorporate perspectives from regions where PT faces security challenges. For instance, Latin American PT users encounter safety concerns [15], particularly related to gender-based violence and personal safety, presenting a Technische Hochschule Ingolstadt, Ingolstadt, Germany 123 210 compelling basis for a cross-cultural comparison between Colombia, Germany, and Korea. Our work involves analyzing security needs with Colombian participants and conceptualizing a DC with German and Korean participants. Employing participatory design techniques in co-creation workshops, we developed both robotand human-like DCs to enhance perceived security in SAVs, and evaluate them in our main study including participants from Colombia, Germany, and Korea. 2 Related work 2.1 Advantages of shared automated vehicles Jeon et al. affirm that the primary perceived benefit of Automated Vehicles (AVs) is safety, attributed to the notion that 94% of vehicle accidents stem from human errors [16, 17]. AVs, equipped with collision avoidance systems and greater data access, hold promise in reducing accidents [18]. In the realm of automated PT, SAVs are poised to revolutionize shared mobility by addressing economics, wherein vehicles often remain empty 95% of the time, according to Sperling [19, 20]. Chen forecasts competitive pricing for SAVs compared to conventional shared mobility, potentially making AVs financially viable [4, 21, 22]. SAVs offer multifaceted benefits, including reduced vehicle ownership, traffic congestion, parking space demand, and emissions [4, 5]. However, their lack of a driver poses significant challenges, particularly concerning in-vehicle security. Studies indicate that personal security concerns might impede SAV adoption [23–25]. Notably, gender-based differences in security perceptions emerge, with women expressing higher levels of anxiety and fear regarding shared mobility [7, 26]. Proposed solutions to mitigate the absence of a driver include Digital Companions (DCs) to alleviate the feeling of being unobserved [10, 27]. These DCs could potentially improve in-vehicle security and crime prevention, as suggested by Sanguinetti et al. [26]. It is imperative to research the design of these DCs due to the critical role they could play in enhancing in-vehicle security and crime prevention, addressing the absence of a human driver and fostering a sense of safety among passengers. 2.2 Designing conversational agents and digital companions In the landscape of conversational agents (CAs), Niess et al. categorize Digital Companions (DCs) into active and passive types, emphasizing the contextual importance of their roles, thereby suggesting a shift in human-DC relationships [28]. Burmester et al. stress the significance of security, feed- 123 Journal on Multimodal User Interfaces (2024) 18:209–228 back, and memory for DCs in Shared Automated Vehicles (SAVs) operating as public transportation [29]. The absence of human drivers in SAVs presents challenges in service and social dynamics, considering the diverse roles typically fulfilled by human drivers in these vehicles [30, 31]. These roles span from psychologist to supervisor [31] underscoring the diverse requirements in (...truncated)