  While recent advances have boosted LM proficiency in linguistic benchmarks,
LMs consistently struggle to reason correctly on complex tasks like
mathematics. We turn to Reinforcement Learning from Human Feedback (RLHF) as a
method with which to shape model reasoning processes. In particular, we explore
two reward schemes, outcome-supervised reward models (ORMs) and
process-supervised reward models (PRMs), to optimize for logical reasoning. Our
results show that the fine-grained reward provided by PRM-based methods
enhances accuracy on simple mathematical reasoning (GSM8K) while, unexpectedly,
reducing performance in complex tasks (MATH). Furthermore, we show the critical
role reward aggregation functions play in model performance. Providing
promising avenues for future research, our study underscores the need for
further exploration into fine-grained reward modeling for more reliable
language models.
