Most present-day voice-based assistants require that users utter a wake-up word to signify that they are addressing the assistant. While this may be acceptable for one-shot requests such as “Turn on the lights”, it becomes tiresome when one is engaged in an extended interaction with such an assistant. To support the goal of developing low-complexity, low-cost alternatives to a wake-up word, we present the results of two studies in which users engage with an assistant that infers whether it is being addressed from the user’s head orientation. In the first experiment, we collected informal user feedback regarding a relatively simple application of head orientation as a substitute for a wake-up word. We discuss that feedback and how it influenced the design of a second prototype assistant designed to correct many of the issues identified in the first experiment. The most promising insight was that users were willing to adapt to the interface, leading us to hypothesize that it would be beneficial to provide visual feedback about the assistant’s belief about the user’s attentional state. In a second experiment conducted using the improved assistant, we collected more formal user feedback on likability and usability and used it to establish that, with high confidence, head orientation combined with visual feedback is preferable to the traditional wake-up word approach. We describe the visual feedback mechanisms and quantify their usefulness in the second experiment.
In Human-Computer Interaction–INTERACT, vol. 2019. 2019.