Exploratory user study on verbalization of explanations*

This work presents an exploratory user study of verbalization of explanations of a robot collaborating with a human to increase its understandability. Levels of explanation (LOEs) were developed to address two aspects of understandability, namely what and why. Based on these aspects, we defined two parameters, verbosity and justification and developed three different LOEs-high, medium and low. User studies were conducted to evaluate the influence of these different LOEs on performance and user interaction in a collaborative gear assembly task. Trends revealed that verbalization of explanation can increase the robot's understandability. Only the trust measure resulted in a statistically significant difference between medium and low LOE.