Towards Understanding Chain-of-Thought Prompting: An Empirical Study of What Matters
Written for the Research library (claude-opus-5-5) from the paper text. Original — aclanthology.org/2023.acl-long.153.pdf
Summary
Chain-of-Thought (CoT) prompting helps large language models solve multi-step problems, but it is unclear which properties of the demonstrated rationales cause the gains. The authors split a rationale into two parts. Bridging objects are the numbers and equations, or the entities, that the model must pass through. Language templates are the surrounding text that guides the model toward them. They then run controlled ablations that alter these parts of the demonstrations. The tests cover arithmetic reasoning (GSM8K) and multi-hop factual QA (Bamboogle), mainly with InstructGPT text-davinci-002. Answers are scored by final-answer metrics and by recall/F1 of the intermediate bridging objects. The main finding is surprising: hand-written demonstrations with logically invalid reasoning still keep roughly 80–90% of CoT's performance, and the model's own reasoning stays coherent. What matters more is that rationales are relevant to the query and that their steps come in the right order. The authors read this as evidence that demonstrations mostly set an output format, while the reasoning ability itself largely comes from pretraining. This has consequences for how few-shot reasoning benchmarks should be interpreted.
Key points
- Data: 800 of the 1319 GSM8K test problems were uniformly sampled for budget reasons, plus all 125 Bamboogle test questions. The demonstrations are exemplars taken from two earlier works, Press et al. (2022) as well as Wei et al. (2022), with only light edits.
- Models and decoding: The main backbone is InstructGPT-175B (text-davinci-002), run with greedy decoding. The appendix adds text-davinci-003, PaLM and Flan-PaLM. Plain GPT-3 175B without instruction tuning gained little from CoT.
- Evaluation:
- Extrinsic: Answer Accuracy on GSM8K and Answer F1 on Bamboogle.
- Intrinsic: Inter. Recall/F1 over the derived bridging objects. For GSM8K these come from the annotated reasoning steps; for Bamboogle they were annotated manually.
- Invalid-reasoning ablation: Premise steps copied from the query were kept, while the later derivation steps were rewritten so they no longer logically support the answer. Performance still reached over 80–90% of standard CoT across the metrics.
- Limitations: Template-heavy symbolic tasks (e.g., Last letter concatenation, Coin flip) were not ablated. The invalid rationales were written by hand rather than generated systematically.
Cited by
- Towards Reasoning Era: A Survey of Long Chain-of-Thought for Reasoning Large Language Models
- Large Language Models Can Self-Improve
- Towards Reasoning in Large Language Models: A Survey
- Large Language Models Can Be Easily Distracted by Irrelevant Context
- To CoT or not to CoT? Chain-of-thought helps mainly on math and symbolic reasoning
- Language Models Don't Always Say What They Think: Unfaithful Explanations in Chain-of-Thought Prompting
- Larger language models do in-context learning differently
- Large Language Models are Better Reasoners with Self-Verification
- MAmmoTH: Building Math Generalist Models through Hybrid Instruction Tuning
- Explainability for Large Language Models: A Survey
Cite
@inproceedings{wang2023understanding,
title = {{Towards Understanding Chain-of-Thought Prompting: An Empirical Study of What Matters}},
author = {Wang, Boshi and Min, Sewon and Deng, Xiang and Shen, Jiaming and Wu, You and Zettlemoyer, Luke and Sun, Huan},
booktitle = {Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)},
year = {2023},
doi = {10.18653/v1/2023.acl-long.153},
url = {https://doi.org/10.18653/v1/2023.acl-long.153}
}References
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