Purpose Service robots can offer benefits to consumers (e.g. convenience, flexibility, availability, efficiency) and service providers (e.g. cost savings), but a lack of trust hinders consumer adoption. To enhance trust, firms add human-like features to robots; yet, anthropomorphism theory is ambiguous about their appropriate implementation. This study therefore aims to investigate what is more effective for fostering trust: appearance features that are more human-like or social functioning features that are more human-like. Design/methodology/approach In an experimental field study, a humanoid service robot displayed gaze cues in the form of changing eye colour in one condition and static eye colour in the other. Thus, the robot was more human-like in its social functioning in one condition (displaying gaze cues, but not in the way that humans do) and more human-like in its appearance in the other (static eye colour, but no gaze cues). Self-reported data from 114 participants revealing their perceptions of trust, anthropomorphism, interaction comfort, enjoyment and intention to use were analysed using partial least squares path modelling. Findings Interaction comfort moderates the effect of gaze cues on anthropomorphism, insofar as gaze cues increase anthropomorphism when comfort is low and decrease it when comfort is high. Anthropomorphism drives trust, intention to use and enjoyment. Research limitations/implications To extend human–robot interaction literature, the findings provide novel theoretical understanding of anthropomorphism directed towards humanoid robots. Practical implications By investigating which features influence trust, this study gives managers insights into reasons for selecting or optimizing humanoid robots for service interactions. Originality/value This study examines the difference between appearance and social functioning features as drivers of anthropomorphism and trust, which can benefit research on self-service technology adoption.

PurposeConversational agents (chatbots, avatars and robots) are increasingly substituting human employees in service encounters. Their presence offers many potential benefits, but customers are reluctant to engage with them. A possible explanation is that conversational agents do not make optimal use of communicative behaviors that enhance relational outcomes. The purpose of this paper is to identify which human-like communicative behaviors used by conversational agents have positive effects on relational outcomes and which additional behaviors could be investigated in future research.Design/methodology/approachThis paper presents a systematic review of 61 articles that investigated the effects of communicative behaviors used by conversational agents on relational outcomes. A taxonomy is created of all behaviors investigated in these studies, and a research agenda is constructed on the basis of an analysis of their effects and a comparison with the literature on human-to-human service encounters.FindingsThe communicative behaviors can be classified along two dimensions: modality (verbal, nonverbal, appearance) and footing (similarity, responsiveness). Regarding the research agenda, it is noteworthy that some categories of behaviors show mixed results and some behaviors that are effective in human-to-human interactions have not yet been investigated in conversational agents.Practical implicationsBy identifying potentially effective communicative behaviors in conversational agents, this study assists managers in optimizing encounters between conversational agents and customers.Originality/valueThis is the first study that develops a taxonomy of communicative behaviors in conversational agents and uses it to identify avenues for future research.

Conversational agents are increasingly used to substitute or augment human service employees. Due to their ability to use human-like communicative behaviors, these agents are theorized to establish social connections with customers. However, the existing literature is ambiguous on how conversational agents should verbally communicate with customers and whether they should be adaptive to customers' verbal behavior. The current study aims to address these gaps, by focusing on the effects of the conversational agent's communication style on the perceived social connection. Two experiments were conducted in which a virtual agent in a hedonic service (Experiment 1) or a utilitarian service (Experiment 2) was manipulated to adapt either a static task-or a social-oriented communication style or mimic the communication style used by the customer in the previous turn. Guided by marketing and human-computer interaction literature, measures for engagement and rapport were used to reveal customers' perceived social connection. Resultsshow that for the hedonic service, rapport was significantly affected by the presence of social cues in the agent's communication style (whether statically or mimicked), while engagement was significantly affected by mimicry. For the utilitarian service, only social cues significantly affected rapport. These findings enrich the Computers As Social Actors paradigm and provide clear guidelines for practitioners.