Communicating Assertiveness in Robotic Storytellers

Social robots have been used to perform the role of storytellers in areas like education and pediatric rehabilitation. With the use of this technology, it is possible to setup different voices, simulate emotional states and even personalities for the same robot. However, finding the best setting that might define a trait for a storyteller robot, is not an easy task. What elements should be manipulated? Should it have a personality? If yes, which one? In this work, we try to answer these questions by studying several setups that will allow us to create an assertive social robot to act as a storyteller. We evaluate the assertiveness impression by manipulating three robot characteristics: posture, pitch, and speech rate. A within-subject study was conducted with 37 participants watching eight videos in which a social robot tells a short story. In each video, the robot presents a different setup, and the participant reports the level of assertiveness of that robot. We found a significant difference between the setups of pitch and posture as well as an acceptable assertive robot’s configuration using a combination of those three characteristics.