On the Role of Beliefs and Trust for the Intention to Use Service Robots: An Integrated Trustworthiness Beliefs Model for Robot Acceptance

International Journal of Social Robotics https://doi.org/10.1007/s12369-022-00952-4 On the Role of Beliefs and Trust for the Intention to Use Service Robots: An Integrated Trustworthiness Beliefs Model for Robot Acceptance Johannes Kraus1 · Linda Miller1 Martin Baumann1 · Marielène Klumpp1 · Franziska Babel1 · David Scholz2 · Julia Merger1 · Accepted: 21 November 2022 © The Author(s) 2023 Abstract With the increasing abilities of robots, the prediction of user decisions needs to go beyond the usability perspective, for example, by integrating distinctive beliefs and trust. In an online study (N = 400), first, the relationship between general trust in service robots and trust in a specific robot was investigated, supporting the role of general trust as a starting point for trust formation. On this basis, it was explored—both for general acceptance of service robots and acceptance of a specific robot—if technology acceptance models can be meaningfully complemented by specific beliefs from the theory of planned behavior (TPB) and trust literature to enhance understanding of robot adoption. First, models integrating all belief groups were fitted, providing essential variance predictions at both levels (general and specific) and a mediation of beliefs via trust to the intention to use. The omission of the performance expectancy and reliability belief was compensated for by more distinctive beliefs. In the final model (TB-RAM), effort expectancy and competence predicted trust at the general level. For a specific robot, competence and social influence predicted trust. Moreover, the effect of social influence on trust was moderated by the robot’s application area (public > private), supporting situation-specific belief relevance in robot adoption. Taken together, in line with the TPB, these findings support a mediation cascade from beliefs via trust to the intention to use. Furthermore, an incorporation of distinctive instead of broad beliefs is promising for increasing the explanatory and practical value of acceptance modeling. Keywords Trust in robots · Acceptance modeling · Intention to use · Beliefs · Theory of planned behavior · UTAUT 1 Introduction Service robots are rapidly advancing to the edge of broad social dissemination in domains of public and private everyday life. This ‘new breed’ of robots is more than automated technology. They interact in social settings, react and adapt to people and situations, and thus are subject to emotional and social responses on the side of their human interaction partners [1, 2]. In this, different users commonly perceive robots differently (e.g., based on their robot-related attitudes; [3–7]) and while certain users might accept and use Johannes Kraus and Linda Miller have equally contributed to this work. B Johannes Kraus 1 Department of Human Factors, Ulm University, Ulm, Germany 2 Cognitive Psychology Lab, University of Koblenz-Landau, Mainz, Germany a robot, others might reject it. Also, different application areas—e.g., in private households vs. public spaces—and levels of autonomy place additional demands on users and human–robot interaction (HRI) design. Therefore, understanding the psychological processes of how people perceive these new technical agents, build up attitudes and expectations, and arrive at decisions in interacting with robots is meaningful to predict decision-making and acceptance in HRI. This, in turn, provides a meaningful basis to inform acceptable, efficient, safe, and human-centered design of robot appearance and interaction strategies (e.g., [8–10]), as well as dissemination strategies at a societal level. The prediction of users’ intentions to interact with and to use technology has been a research focus for many years with essentially two predominant traditions: the technology acceptance models (the different versions of the technology acceptance model, TAM; e.g., [11–14]) and frameworks incorporating trust as a main antecedent of technologyrelated behavior (e.g., [15, 16]). While these two perspectives 123 International Journal of Social Robotics share a common underlying theoretical tradition, they are typically discussed separately. A theoretical integration of the two perspectives is promising for better understanding the psychological processes associated with HRI and to facilitate a positive integration. The shared underlying theoretical approach are attitude-to-behavior models, which theoretically substantiated the study of the cascade from beliefs over attitudes to behavioral intentions—particularly in the theory of reasoned action (TRA; [17]) and the theory of planned behavior (TPB; [18]) as an advancement of the former. The TPB focuses on psychological variables affecting an intended behavior [17, 19]. The basic assumption is that behavior is essentially influenced by the intention to perform that behavior. This intention is assumed to build on the three core constructs of the TPB—social norm, attitude towards the behavior, and perceived behavioral control—which, in turn, are based on associated beliefs. The TPB was transferred to the domain of technology acceptance by the TAM and its various advancements. The Unified Theory of Acceptance and Use of Technology (UTAUT) is a recent and widely used derivation of the TAM tradition. However, it is the result of a scientific process over several decades, in which theorizing developed away from the original idea of attitude-based behavior prediction in the sense of the TPB. Presently, only a partially coherent conglomerate of technology acceptance models exists that are not well integrated in terms of modeled constructs, underlying definitions, and measurement of constructs. Especially, at this point, there is no systematic investigation of the belief structure that underlies the adoption of robots. If constructs are not welldefined and theoretically integrated, acceptance models like the UTAUT provide only restricted value for understanding the psychological foundation of decisions in HRI (see also [20]). This hinders deriving meaningful design implications, reliable prediction of user behavior, and cumulative improvements of the scientific understanding of technology acceptance. A promising direction here is replacing overlapping, atheoretical beliefs with more distinct and theoretically founded ones and integrating these in the beliefs-attitudes cascade from the TPB to predict the intention to use. Thereby, a meaningful extension is the inclusion of trust as a mediator. 1.1 Goal and Contribution of this Research Against this background, this research aims at an integration of beliefs from different theoretical streams (TAM, UTAUT, trust) into the original theoretical structure of the TPB. In doing so, the general assumption of attitude-based definitions of trust in automation (e.g., [15]) that trust mediates the relationship between beliefs about technology and the intention to use is empirically tested. As a first step in un (...truncated)