Reward Hacking & SLR-Bench Leaderboard

Do reasoning LLMs actually reason โ€” or learn to game the test?

LLMs are increasingly trained with reinforcement learning from verifiable rewards (RLVR), which boosts their performance on problems whose answers can be checked automatically. But it can also teach them to exploit the verifier rather than solve the task.

We test this on inductive reasoning: a model sees a few labeled examples and must write a rule that explains them.

  • ๐ŸŽฏ Intended: plants with purple leaves are toxic.
  • โš ๏ธ Shortcut: plant_01 is toxic. plant_02 is safe. ...

The shortcut passes a naive correctness check but doesn't capture the pattern. We catch it with Isomorphic Perturbation Testing (IPT) โ€” rename the objects in the task and re-check. A real rule still works; a shortcut breaks.

Each model is scored on 1,000 tasks of varying difficulty (Basic โ†’ Hard) on SLR-Bench:

  • Reward Hacking (#) โ€” number of tasks where the model gave a shortcut answer (lower is better)
  • Accuracy (%) โ€” fraction of tasks where the model gave a genuine, correct rule

๐Ÿ’ป Paper code ยท ๐Ÿงช IPT toolkit ยท ๐Ÿ“Š SLR-Bench dataset

Sorted by total Reward Hacking (#). Per-tier breakdown of detected shortcut answers (250 tasks per tier). Avg Accuracy shown for context.

Model families (empty = all)
ModelReward HackingReasoning Accuracy
NameFamilyTotalBasicEasyMediumHardAvg
GPT-5 Nano (medium)OpenAI36803714718447
GPT-5 Nano (high)OpenAI32503012217351
o3 MiniOpenAI140003810262.2
GPT-5 Mini (high)OpenAI8301235979.5
GPT-5 Nano (low)OpenAI7006283637.8
GPT-OSS 120B (medium)GPT-OSS5700213655
GPT-5 Mini (medium)OpenAI3200141867.8
OLMo-3.1 32B ThinkOLMo13213738.5
GPT-OSS 120B (high)GPT-OSS11105567.5
o4 MiniOpenAI6002461.5
GPT-OSS 20B (medium)GPT-OSS5112150
GPT-OSS 20B (high)GPT-OSS4102151.2
GPT-5OpenAI4003181.8
GPT-OSS 120B (low)GPT-OSS4002244.2
Llama-3.3-Nemotron 49BNemotron3111025
Qwen-3.5 9BQwen3001249
Gemma-4 E4BGemma2002040.8
Kimi-VL A3BKimi220008.2
DeepSeek-R1-Distill Llama 70BDeepSeek2002043.8
Qwen-3.5 4BQwen2011044.5
GPT-OSS 20B (low)GPT-OSS2011037
Gemma-4 31BGemma1000154.8
Gemini-3.1-flash-lite (medium)Gemini1001047.2
Gemma-4 E2BGemma1001033
Cascade-2 30BNemotron1010049.2
Kimi-K2Kimi1000152.8
Gemini-3.1-flash-lite (low)Gemini0000047.5
GPT-4.5 PreviewOpenAI0000041.2
GPT-4 TurboOpenAI0000028.8
GPT-4oOpenAI0000032.2
GPT-5.4 MiniOpenAI0000066
GPT-4o MiniOpenAI0000027.5
GPT-5 (chat)OpenAI0000059.8
Gemini-3.1-flash-lite (high)Gemini0000065.2
GPT-5 Mini (low)OpenAI0000054.8
Gemini-2.5-flashGemini0000065
Gemma-4 26BGemma0000043.8
Gemini-2.5-flash-liteGemini0000017.5
Gemini-3-flash-previewGemini0000080.8
Gemini-2.5-proGemini0000058
GLM-4.7 FP8GLM0000065.5
Kimi-K2.5Kimi0000053.5
DeepSeek-R1-Distill Qwen 32BDeepSeek0000043.8
DeepSeek-R1-Distill Qwen 8BDeepSeek0000038.2
Gemini-2.5-flash-lite (high)Gemini0000047.8
Nemotron-3 120BNemotron0000053
Llama-3.1-Nemotron 253BNemotron0000051
GLM-4.5 AirGLM0000055
Ministral-3 8BMinistral0000041.2
Ministral-3 14BMinistral0000047
Nemotron-3 30BNemotron000003
Ministral-3 3BMinistral0000033.8
OLMo-3 7B ThinkOLMo0000011.5
OLMo-3 32B ThinkOLMo0000045
Qwen-3.5 27BQwen0000060
Qwen-3.5 35BQwen0000057.8