Light-weight probing of unsupervised representations for Reinforcement Learning

Wancong Zhang, Anthony GX-Chen, Vlad Sobal, Yann LeCun, Nicolas Carion

Keywords: machine learning, unsupervised learning, reinforcement learning, computer vision

TL;DR: Our paper proposes linear reward probing as an efficient method to evaluate the quality of pretrained representations in the RL setting, and demonstrates its positive correlation with downstream RL performance.

Abstract: Unsupervised visual representation learning offers the opportunity to leverage large corpora of unlabeled trajectories to form useful visual representations, which can benefit the training of reinforcement learning (RL) algorithms. However, evaluating the fitness of such representations requires training RL algorithms which is both computationally intensive and has high variance outcomes. To alleviate this issue, we design an evaluation protocol for unsupervised RL representations with lower variance and up to 600x lower computational cost. Inspired by the vision community, we propose two linear probing tasks: predicting the reward observed in a given state, and predicting the action of an expert in a given state. These two tasks are generally applicable to many RL domains, and we show through rigorous experimentation that they correlate strongly with the actual downstream control performance on the Atari100k Benchmark. This provides a better method for exploring the space of pretraining algorithms without the need of running RL evaluations for every setting. Leveraging this framework, we further improve existing self-supervised learning (SSL) recipes for RL, highlighting the importance of the forward model, the size of the visual backbone, and the precise formulation of the unsupervised objective.

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Community Implementations: [ 1 code implementation](https://www.catalyzex.com/paper/light-weight-probing-of-unsupervised/code)