The Effects of Anthropomorphism and Non-verbal Social Behaviour in Virtual Assistants

The adoption of virtual assistants is growing at a rapid pace. However, these assistants are not optimised to simulate key social aspects of human conversational environments. Humans are intellectually biased toward social activity when facing anthropomorphic agents or when presented with subtle social cues. In this paper, we test whether humans respond the same way to assistants in guided tasks, when in different forms of embodiment and social behaviour. In a within-subject study (N=30), we asked subjects to engage in dialogue with a smart speaker and a social robot. We observed shifting of interactive behaviour, as shown in behavioural and subjective measures. Our findings indicate that it is not always favourable for agents to be anthropomorphised or to communicate with nonverbal cues. We found a trade-off between task performance and perceived sociability when controlling for anthropomorphism and social behaviour.