The Sound Makes the Greeting: Interpersonal Functions of Intonation in Human-Robot Interaction

In this paper, we study the effects of different ways of producing greetings in human-robot interaction. We first generated computer utterances of verbal greetings, whose intonation contours, we then manipulated using Praat. Each utterance was matched with a video of a robot waving a greeting at the observer. Altogether, the experiment uses two lexical items (hello vs. hi), three robots and four different intonation contours. The videos were distributed over different questionnaires so that each participant only got to see each robot once. The results reveal that native speakers of English rate the robots significantly different concerning friendliness, assertiveness, and engagement depending on the intonation contours. However, these effects differ for the different lexical items, and the apparently non-conventional hi with rising intonation contour was in fact rated as most engaging.