Explanation Augmented Feedback in Human-in-the-Loop Reinforcement Learning

Human-in-the-loop Reinforcement Learning (HRL) aims to integrate human guidance with Reinforcement Learning (RL) algorithms to improve sample efficiency and performance. The usual human guidance in HRL is binary evaluative "good" or "bad" signal for queried states and actions. However, this suffers from the problems of weak supervision and poor efficiency in leveraging human feedback. To address this, we present EXPAND (Explanation Augmented Feedback) which allows for explanatory information to be given as saliency maps from the human in addition to the binary feedback. EXPAND employs a state perturbation approach based on the state salient information to augment the feedback, reducing the number of human feedback signals required. We choose two domains to evaluate this approach, Taxi and Atari-Pong. We demonstrate the effectiveness of our method on three metrics, environment sample efficiency, human feedback sample efficiency, and agent gaze. We show that our method outperforms our baselines. Finally, we present an ablation study to confirm our hypothesis that augmenting binary feedback with state salient information gives a boost in performance.