Getting Priorities Right: Intrinsic Motivation with Multi-Objective Reinforcement Learning

Intrinsic motivation is a common method to facilitate exploration in reinforcement learning agents. Curiosity is thereby supposed to aid the learning of a primary goal. However, indulging in curiosity may also stand in conflict with more urgent or essential objectives such as self-sustenance. This paper addresses the problem of balancing curiosity, and correctly prioritising other needs in a reinforcement learning context. We demonstrate the use of the multi-objective reinforcement learning framework C-MORE to integrate curiosity, and compare results to a standard linear reinforcement learning integration. Results clearly demonstrate that curiosity can be modelled with the priority-objective reinforcement learning paradigm. In particular, C-MORE is found to explore robustly while maintaining self-sustenance objectives, whereas the linear approach is found to over-explore and take unnecessary risks. The findings demonstrate a significant weakness of the common linear integration method for intrinsic motivation, and the need to acknowledge the potential conflicts between curiosity and other objectives in a multi-objective framework.