A Mechanistic Analysis of a Transformer Trained on a Symbolic Multi-Step Reasoning Task

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Hauptverfasser: Brinkmann, Jannik, Sheshadri, Abhay, Levoso, Victor, Swoboda, Paul, Bartelt, Christian
Format: Preprint
Veröffentlicht: 2024
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author Brinkmann, Jannik
Sheshadri, Abhay
Levoso, Victor
Swoboda, Paul
Bartelt, Christian
author_facet Brinkmann, Jannik
Sheshadri, Abhay
Levoso, Victor
Swoboda, Paul
Bartelt, Christian
contents Transformers demonstrate impressive performance on a range of reasoning benchmarks. To evaluate the degree to which these abilities are a result of actual reasoning, existing work has focused on developing sophisticated benchmarks for behavioral studies. However, these studies do not provide insights into the internal mechanisms driving the observed capabilities. To improve our understanding of the internal mechanisms of transformers, we present a comprehensive mechanistic analysis of a transformer trained on a synthetic reasoning task. We identify a set of interpretable mechanisms the model uses to solve the task, and validate our findings using correlational and causal evidence. Our results suggest that it implements a depth-bounded recurrent mechanisms that operates in parallel and stores intermediate results in selected token positions. We anticipate that the motifs we identified in our synthetic setting can provide valuable insights into the broader operating principles of transformers and thus provide a basis for understanding more complex models.
format Preprint
id arxiv_https___arxiv_org_abs_2402_11917
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Mechanistic Analysis of a Transformer Trained on a Symbolic Multi-Step Reasoning Task
Brinkmann, Jannik
Sheshadri, Abhay
Levoso, Victor
Swoboda, Paul
Bartelt, Christian
Machine Learning
Transformers demonstrate impressive performance on a range of reasoning benchmarks. To evaluate the degree to which these abilities are a result of actual reasoning, existing work has focused on developing sophisticated benchmarks for behavioral studies. However, these studies do not provide insights into the internal mechanisms driving the observed capabilities. To improve our understanding of the internal mechanisms of transformers, we present a comprehensive mechanistic analysis of a transformer trained on a synthetic reasoning task. We identify a set of interpretable mechanisms the model uses to solve the task, and validate our findings using correlational and causal evidence. Our results suggest that it implements a depth-bounded recurrent mechanisms that operates in parallel and stores intermediate results in selected token positions. We anticipate that the motifs we identified in our synthetic setting can provide valuable insights into the broader operating principles of transformers and thus provide a basis for understanding more complex models.
title A Mechanistic Analysis of a Transformer Trained on a Symbolic Multi-Step Reasoning Task
topic Machine Learning
url https://arxiv.org/abs/2402.11917