How to use non-linguistic utterances to convey emotion in child-robot interaction

Vocal affective displays are vital for achieving engaging and effective Human-Robot Interaction. The same can be said for linguistic interaction also, however, while emphasis may be placed upon linguistic interaction, there are also inherent risks: users are bound to a single language, and breakdowns are frequent due to current technical limitations. This work explores the potential of non-linguistic utterances. A recent study is briefly outlined in which school children were asked to rate a variety of non-linguistic utterances on an affective level using a facial gesture tool. Results suggest, for example, that utterance rhythm may be an influential independent factor, whilst the pitch contour of an utterance may have little importance. Also evidence for categorical perception of emotions is presented, an issue that may impact important areas of HRI away from vocal displays of affect.