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REVIEW 4 major objections 4 minor 27 references

Superstition in the Network: Deep Reinforcement Learning Plays Deceptive Games

T0 review · 4 major / 4 minor · reviewed 2026-08-14 · deepseek-v4-flash

Pith's one-line read A deep reinforcement learner, A2C, misses optimal play on nearly every level of four deceptive games and invents a superstitious ritual.

desk verdict A solid, modest empirical study of one A2C configuration on four hand-designed deceptive games, with a genuinely interesting superstition result, but the title and conclusion overgeneralize from A2C to deep RL as a class. read the letter →

arxiv 1908.04436 v1 pith:5OSDD2G6 submitted 2019-08-12 cs.LG cs.AIstat.ML

classification cs.LGcs.AIstat.ML
keywords deepreinforcementlearningA2Cdeceptivegamesrewardstructurecreditassignmentdelayedsuperstitioninlearnedpoliciesgeneralvideogameplaying
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper tries to establish that deep reinforcement learning can be reliably deceived by the reward structure of an environment, not just by sparse rewards or partial observability. To show this, the authors designed four small games—DeceptiCoins, WaferThinMints, Flower, and Invest—each built around a distinct way of tempting an agent away from optimal play, and trained a widely used model-free actor-critic algorithm, A2C, on pixels. They report that A2C fails to find the optimal policy in every game except one level of one game, and that watching the trained agents reveals the mechanism of failure. The paper also proposes an initial typology of deceptions: lack of hierarchical understanding, subverted generalization, delayed reward, and delayed gratification. If the claim is right, benchmark results on standard arcade games overstate how robust current reward-driven learning is.

What carries the argument

The load-bearing object is the deceptive game suite itself, combined with the A2C training protocol. Each of the four games is a minimal environment whose reward schedule punishes the very assumption a reward-driven learner must make: that immediate positive signals can be trusted as guides. DeceptiCoins uses an irreversible early choice, WaferThinMints makes the same item switch from positive to lethal, Flower makes fast collection destructive, and Invest makes the agent incur a penalty before a delayed payoff. The machinery does its work by making the failure visible and repeatable: the same superstitious corner-waiting behavior appears across independent training runs in Invest, and the Flower agent's performance declines as it gets better. Comparing these behaviors with forward-model planners isolates which failures come from the learning rule rather than from the games themselves.

What would settle it

Train A2C on DeceptiCoins level 3 for fifty million frames instead of five million. If it then consistently takes the higher-reward right-side path, the reported failure is a training-budget artifact rather than a robust deception. Likewise, give A2C a direct encoding of the avatar's fullness meter in WaferThinMints; if that alone yields safe mint collection, then that deception depends on the pixel-only representation rather than the reward structure itself.

Watch

Extended reading notes

Core claim

The central discovery is that a standard deep reinforcement learner, A2C, reliably misses the optimal policy in four deceptive games, and the way it fails is informative. In DeceptiCoins, the agent converges to a suboptimal path once the level is large enough; in WaferThinMints, it learns that mints are good but cannot master the rule that the tenth mint kills it, and the stochastic mint-placing waiter keeps the game from converging; in Flower, the agent's improving skill backfires because collecting seedlings prevents them from maturing, so its score drops as training progresses; and in Invest, it learns to invest only with the quickest-paying banker and then runs to a fixed corner to wait for the payout, an arbitrary ritual the authors call superstitious. The paper argues these four failure modes correspond to distinct deceptions—lack of hierarchical understanding, subverted generalization, delayed reward, and delayed gratification—and uses six planning agents that rely on a forward model as a comparison to show that model-free learning fails differently from planning with a forward model.

Load-bearing premise

The conclusion would collapse if a different deep RL configuration did not fail: the paper uses one algorithm—A2C with a fixed architecture, default hyperparameters, and five million training frames—and assumes the four games isolate the intended deceptions rather than confounding pixel observation or randomness.

Editorial extensions

If this is right

  • If one standard model-free deep RL algorithm can be reliably deceived by such simple reward structures, then strong performance on standard arcade benchmarks is not evidence that a method handles delayed or trap-like rewards.
  • The Flower result implies that training can make a reward-driven agent monotonically worse: improving its ability to collect flowers destroys the flowers' growth, so competence and score move in opposite directions.
  • The Invest result implies that deep RL policies can encode stable but causally false associations, since separate training runs produced the same arbitrary waiting-spot ritual.
  • Because planning agents with forward models fail on different games than the learning agent does, deceptive games can separate failures of credit assignment from failures of search or representation.
  • The proposed typology gives algorithm builders four concrete stressors—hierarchical abstraction, generalization under changing effects, delayed reward, and delayed gratification—to test before deploying an agent in an environment with adversarial or natural reward traps.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A natural extension is to test value-based methods and recurrent policies on the same four games; if they also fail, the result generalizes from actor-critic training to model-free deep RL broadly, while if they succeed it means the deception is specific to A2C's update rule or architecture.
  • The superstition in Invest suggests a cheap diagnostic for causal confusion: remove the spatial cue by making the waiting spot irrelevant, and see whether the learned policy collapses or adapts; this would test whether the policy truly depends on the spurious location.
  • The delayed-reward game could be made progressively harder by randomizing the investment payoff time, which would tell whether the agent can learn to wait at all or would simply develop longer and more elaborate superstitions.
  • In real deployments where rewards are naturally delayed—such as medical or financial decisions—this paper implies that a model-free agent trained on reward alone may lock onto accidental correlates and should be audited for behavior that has no causal link to outcomes.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 4 minor

Summary. The paper studies failure modes of deep reinforcement learning by introducing four 'deceptive games' implemented in the GVGAI framework: DeceptiCoins, WaferThinMints, Flower, and Invest. The authors train A2C (OpenAI Baselines, default Atari-style hyperparameters, five seeds, five million frames) on these games, evaluate each agent on 150 episodes, and compare the resulting average scores against six planning agents. They report that A2C converges to suboptimal policies in most of the games, including a 'superstitious' corner-waiting behavior in Invest, and propose an initial typology of deceptions: lack of hierarchical understanding, subverted generalization, delayed reward, and delayed gratification. The central qualitative claim is that deep reinforcement learners are easily deceived by reward structures that lead away from optimal policies.

Significance. If the empirical findings are supported, this is a useful contribution to the growing literature on failure modes of deep RL. The paper's strengths are its use of a consistent evaluation setup across four games, a comparison with six planning agents that differ in mechanism, and a concrete proposal of deception categories that could guide future benchmark design. The reported consistency across five training seeds is encouraging. However, the paper's central conclusion is broader than its evidence: only one algorithm (A2C) with one hyperparameter configuration is tested, the quantitative results lack variance measures and statistical tests, and the most distinctive behavioral claims are based on qualitative video inspection. These issues need to be addressed before the general claim about 'deep reinforcement learners' can be accepted.

major comments (4)
  1. [Conclusion / Abstract] The conclusion that 'deep reinforcement learners are easily deceived' is not supported by evidence from a single algorithm, A2C, with one default hyperparameter configuration (Methods: 'Instead of tuning the algorithms for the games, we designed the games for the algorithms'). The Discussion itself concedes that 'numerous modifications' of deep RL could potentially solve these games. Please either test at least one additional algorithm (e.g., DQN or PPO) under comparable conditions, or narrow the claim in the abstract and conclusion to 'this A2C configuration is easily deceived by these games.'
  2. [Table 1 / Comparison with planning algorithms] Table 1 reports average scores across evaluation runs, but no error bars, standard deviations, per-seed breakdowns, or statistical tests are provided for any algorithm. This makes it impossible to assess whether the A2C scores (e.g., DeceptiCoins level 2: 3.79 vs. optimal 5.0; Invest: 69.6 vs. Return42's 190.12) are reliable differences or within-run noise. Please report variance measures and clarify how the five independently trained A2C agents are aggregated into the single A2C row.
  3. [Invest / Results] The 'superstition' claim is load-bearing for the paper's title and discussion, but it rests entirely on qualitative video inspection. The text states that the agent 'runs to the far right corner and waits' and that the time to reach the corner 'correlates with the arrival of the delayed reward,' yet no quantitative evidence is provided. Please include position-over-time traces, waiting-time statistics, and, for all five seeds, a demonstration that the corner waiting is temporally correlated with reward payout. Without such data, the claim cannot be independently evaluated.
  4. [WaferThinMints / Results and Methods] The paper explicitly states that WaferThinMints 'did not converge' and 'might have benefited from more training time.' Interpreting this as evidence of deception is undercut by the acknowledged non-convergence: a truncated training run may fail for reasons unrelated to the game's reward structure. Please provide a convergence criterion, longer training results, or an explicit analysis of learning dynamics. Similarly, the Flower claim that 'the agent gets worse over time' is supported only by a training curve that is not shown; include the training curves with error bars for all seeds.
minor comments (4)
  1. [Methods / Reproducibility] The paper does not provide code, game descriptions, or evaluation scripts. Since the central evidence is empirical and behavioral, releasing the VGDL game files and the A2C evaluation code would substantially strengthen the work and allow replication.
  2. [Comparison with planning algorithms] The comparison between A2C and planning agents is described as 'apples and oranges,' but the paper does not specify how much computation the planning agents are allowed per episode. A sentence clarifying the total planning budget relative to the RL training budget would help readers interpret the comparison.
  3. [Deceptive Games / DeceptiCoins] The optimal scores for DeceptiCoins are not given explicitly. Reporting the maximum achievable score for each level would make Table 1 more interpretable, because the reader cannot tell whether a score of 2.0 out of a possible 5.0 represents a partial or total failure.
  4. [References] The reference to Anderson et al. 2018 is cited for the previous deceptive-games suite, but the current paper does not clearly state which games are new in this work and which were introduced previously. Please clarify the relationship.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the A2C results are fresh empirical observations, and the self-citation to prior deceptive-game work supplies inputs rather than the paper's conclusions.

full rationale

This paper does not contain a derivation chain in which a predicted quantity is equivalent to an input by construction. The central claim, that A2C fails to find optimal policies on the four games, is supported by new training runs with fixed OpenAI Baselines hyperparameters, five random seeds, and 150 evaluation episodes per agent; none of these results are fitted parameters renamed as predictions. The deceptive games themselves come from Anderson et al. 2018, which overlaps in authorship, but that citation supplies game implementations and design motivations, not the conclusion that A2C is deceived. The 'optimal strategy' definitions are author-specified experimental targets, not quantities derived from the algorithm, so defining failure relative to them is a measurement design rather than a circular reduction. The paper's own Discussion concedes that 'numerous modifications' of deep RL could potentially solve these games, which narrows the scope of the generalization but does not make the empirical finding circular. The only self-citations are normal provenance for the GVGAI setup and prior deceptive-game benchmarks, and they are not load-bearing evidence for the observed A2C behavior. Accordingly, the appropriate finding is no significant circularity.

Assumptions & free parameters 4 free parameters · 4 assumptions · 0 invented entities

The paper introduces no new physical or mathematical entities. Its central result rests on hand-designed game parameters and qualitative behavioral analysis, all of which are domain assumptions rather than derived equations.

free parameters (4)
  • WaferThinMints mint limit = 9
    Chosen by hand: collecting the 10th mint kills the agent. This threshold is central to the 'subverted generalization' trap.
  • Invest banker payoff schedules = Green: 3->5 after 30 ticks; Red: 7->15 after 60 ticks; Blue: 5->10 after 90 ticks
    Hand-selected delays and payouts create the delayed-reward credit assignment problem the paper studies.
  • DeceptiCoins level 3 size = not specified numerically in the paper
    The level was made large enough that random exploration does not find the higher-reward path, which is the basis for the 'lack of hierarchical understanding' failure.
  • Training duration = 5,000,000 frames
    Standardized after initial testing showed convergence within 2M frames; this choice affects whether observed failures are due to deception or under-training.
assumptions (4)
  • domain assumption A2C with Atari-style pixel inputs and default hyperparameters represents deep reinforcement learning broadly.
    The conclusion generalizes from one algorithm to 'deep reinforcement learners'; this enters in Methods and Conclusion.
  • domain assumption The four custom games are valid instantiations of the named deception categories and are not confounded by observation or stochasticity.
    The authors attribute failures to reward-structure deceptions without control games or ablations; this enters in the Deceptive Games section.
  • domain assumption Video-based qualitative analysis is sufficient to infer learned behavior such as superstition.
    The Invest superstition claim rests on watching replays and describing behavior, with no quantitative measure of position-reward correlation; this enters in the Invest results.
  • domain assumption Planning agents and A2C are comparable despite different resource budgets.
    Planning agents get a forward model and 40ms per action, while A2C gets 5M training frames; the authors acknowledge this is 'apples and oranges' in the Conclusion.

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Cite this review

Pith. "Pith review of Superstition in the Network: Deep Reinforcement Learning Plays Deceptive Games." pith.science (2026). https://pith.science/paper/5OSDD2G6

@misc{pith2026190804436,
  author       = {Pith},
  title        = {Pith review of: Superstition in the Network: Deep Reinforcement Learning Plays Deceptive Games},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/5OSDD2G6}},
  note         = {Machine review of arXiv:1908.04436}
}
read the original abstract

Deep reinforcement learning has learned to play many games well, but failed on others. To better characterize the modes and reasons of failure of deep reinforcement learners, we test the widely used Asynchronous Actor-Critic (A2C) algorithm on four deceptive games, which are specially designed to provide challenges to game-playing agents. These games are implemented in the General Video Game AI framework, which allows us to compare the behavior of reinforcement learning-based agents with planning agents based on tree search. We find that several of these games reliably deceive deep reinforcement learners, and that the resulting behavior highlights the shortcomings of the learning algorithm. The particular ways in which agents fail differ from how planning-based agents fail, further illuminating the character of these algorithms. We propose an initial typology of deceptions which could help us better understand pitfalls and failure modes of (deep) reinforcement learning.

Figures

Figures reproduced from arXiv: 1908.04436 by the authors.

Figure 2
Figure 2. The first level of WaferThinMints suboptimal strategy. By comparison, a randomly initialized agent is very likely to select the easy path, since it starts next to it, before being forced to move toward the exit. The training curve for level 3 shows a significant drop in performance at the beginning of training. The video footage suggests that the agent learns the concept of the gold coins and is attempting to collec… view at source ↗
Figure 4
Figure 4. Invest level 1 too good at collecting the flowers, and they no longer have a chance to grow, lowering the score. Watching agent replays further confirms this, the agent finds a circuit through all the flowers and then gets better at quickly moving through this circuit. The agent perfectly falls for the deceit and has no way back unless it ignores the immediate rewards. Invest (Inv) Game Invest is a game where agents… view at source ↗

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