Deep Reinforcement Learning and The Tale of Two Temporal Difference Errors

Fuente: arXiv
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Main Authors: Rojas, Juan Sebastian, Lee, Chi-Guhn
Format: Preprint
Published: 2026
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author Rojas, Juan Sebastian
Lee, Chi-Guhn
author_facet Rojas, Juan Sebastian
Lee, Chi-Guhn
contents The temporal difference (TD) error was first formalized in Sutton (1988), where it was first characterized as the difference between temporally successive predictions, and later, in that same work, formulated as the difference between a bootstrapped target and a prediction. Since then, these two interpretations of the TD error have been used interchangeably in the literature, with the latter eventually being adopted as the standard critic loss in deep reinforcement learning (RL) architectures. In this work, we show that these two interpretations of the TD error are not always equivalent. In particular, we show that increasingly-nonlinear deep RL architectures can cause these interpretations of the TD error to yield increasingly different numerical values. Then, building on this insight, we show how choosing one interpretation of the TD error over the other can affect the performance of deep RL algorithms that utilize the TD error to compute other quantities, such as with deep differential (i.e., average-reward) RL methods. All in all, our results show that the default interpretation of the TD error as the difference between a bootstrapped target and a prediction does not always hold in deep RL settings.
format Preprint
id arxiv_https___arxiv_org_abs_2603_21921
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Deep Reinforcement Learning and The Tale of Two Temporal Difference Errors
Rojas, Juan Sebastian
Lee, Chi-Guhn
Machine Learning
Artificial Intelligence
The temporal difference (TD) error was first formalized in Sutton (1988), where it was first characterized as the difference between temporally successive predictions, and later, in that same work, formulated as the difference between a bootstrapped target and a prediction. Since then, these two interpretations of the TD error have been used interchangeably in the literature, with the latter eventually being adopted as the standard critic loss in deep reinforcement learning (RL) architectures. In this work, we show that these two interpretations of the TD error are not always equivalent. In particular, we show that increasingly-nonlinear deep RL architectures can cause these interpretations of the TD error to yield increasingly different numerical values. Then, building on this insight, we show how choosing one interpretation of the TD error over the other can affect the performance of deep RL algorithms that utilize the TD error to compute other quantities, such as with deep differential (i.e., average-reward) RL methods. All in all, our results show that the default interpretation of the TD error as the difference between a bootstrapped target and a prediction does not always hold in deep RL settings.
title Deep Reinforcement Learning and The Tale of Two Temporal Difference Errors
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2603.21921