Human behavioural responses to robot head gaze during robot-to-human handovers

A robot that can fluently hand over objects to people can be useful in many applications. In an effort to develop a fluent robot-to-human handover system, this work investigates people's behavioural responses to a robot that hands over objects to them while using different types of gaze cues. In our previous work, we found empirical evidence that the use of a robot's head gaze can affect a person's timing of reaching towards the offered object. In this paper, we investigate this effect further by exploring the manner in which human's reaching and gaze behaviours are affected by a robot's head gaze. We conducted a video-based investigation of 97 naïve participants' behavioural responses to robot-to-human handovers. Through a frame-by-frame analysis, we recorded a detailed timeline of the robot's and human's gaze and reaching behaviours. Results confirm the finding from our previous study that the robot's head gaze can significantly impact the timing of human receiver's reaching behaviour during handovers. In addition, our results demonstrate that the robot's head gaze affects human's gaze behaviour during handovers, and this effect explains some unexpected findings in our previous work.