Embodying a Virtual Agent in a Self-Driving Car: A Survey-Based Study on User Perceptions of Trust, Likeability, and Anthropomorphism

Introduction

Virtual agents represent a shift toward more natural interactions with technology, for example, Siri, Google Assistant, Alexa, and Cortana. In everyday life, they enable quick access to web content and other functionalities through computers, mobile devices, and even our cars. Using virtual agents for in-car interactions may benefit drivers, enhancing cockpit features (e.g., music and navigation) with novel user interfaces (Weng et al., 2016). Recent implementations have come in various forms, such as mobile apps (e.g., Apple CarPlay and Google Assistant Driving Mode), in-car dedicated devices (e.g., Echo Auto, Chris, and Garmin Speak; Lugano, 2017), and proprietary personal agents from car manufacturers (e.g., Honda, BMW, Mercedes, and Volkswagen; Majji & Baskaran, 2021). With the rise of highly automated cars, new concepts of virtual agents (Ajitha & Nagra, 2021; Okamoto & Sano, 2017) are emerging with new roles. Beyond delivering complex messages about driving and road safety, particularly during handover procedures, these virtual agents embody the artificial intelligence of the automated system. In this context, the perception of trust toward such agents plays an important role in adopting this new technology.

Previous research showed that providing a visual appearance, specifically an anthropomorphic one, might be a way of ensuring trust toward these agents (Meng et al., 2021; Ekman et al., 2018; Waytz et al., 2014). Similar to human-to-human relationships, in which people tend to judge others’ social warmth, honesty, trustworthiness, and intellectual competence based on facial appearance or attire (Zebrowitz & Montepare, 2008; Willis & Todorov, 2006; Smith et al., 2018), human – virtual-agent interactions are greatly influenced by visual appearance. Research revealed that the visual appearance of an embodied virtual agent tends to have an impact on user first impressions (ter Stal et al., 2020), perceptions of competence, intelligence, trust, and acceptance. Several studies have shown that pedagogical agents’ visual attributes, including realism, gender, and ethnicity, significantly affect student self-efficacy and motivation (Baylor & Kim, 2004; Gulz & Haake, 2006; McDonnell et al., 2012; Ashby Plant et al., 2009).

Further, it appears that the appropriate appearance for a virtual agent may vary with the use case or context of use. For example, agents with realistic human-like looks tend to be preferred for health-related roles, whereas cartoon-like human looks are preferred for social interactions (Ring et al., 2014). Also, the level of realism in human-like representations encourages positive subjective user ratings (Yee et al., 2007). Zoomorphic agents tend to be associated with entertainment, education, and therapy-related roles, and agents with more mechanical looks are expected to carry out security-related tasks (Dingjun et al., 2010; Kalegina et al., 2018). Parmar et al. (2018) provided evidence that a virtual health agent designed with attire fitting the role (e.g., a white coat) was perceived to be more trustworthy, reassuring, and persuasive than an agent whose attire was not role appropriate (e.g., a casual outfit).