The Interplay of Paralinguistic Cues and Expressions of Certainty in Human-Human and Human-Agent Interactions

There is limited understanding of how paralinguistic cues relate to expressions of certainty in human-agent vs. human-human interactions. We collected data through two phases: (1) we analyzed the pronunciation of phrases from participants across different interaction scenarios and with different certainty levels to establish what cues people use to express certainty; and (2) through an online survey, we presented participants with recordings of humans and agents uttering phrases across different scenarios, and asked participants to identify the certainty level of each recording. We found that it is easier for people to express and recognize low certainty consistently, vs. high certainty, in both human-human and human-agent interactions. Additionally, people tend to rate utterances from agents with lower certainty than humans, even when using the same cues. We contribute design recommendations for agents using paralinguistic cues to express varying levels of certainty across different interaction contexts.