A recent paper on arXiv cs.CL introduces Concept-Targeted Attribution (CTA), a framework designed to explain how internal concept representations arise within a prompt. Unlike traditional transcoder attribution graphs that focus on next-token probability, CTA trains attribution graphs specifically for linear probe directions. This approach aims to reveal probe-specific circuits that illuminate the internal computations behind a concept's emergence, independent of its expression in the generated token.
Key Points
- Concept-Targeted Attribution (CTA) trains attribution graphs relative to a linear probe direction.
- This method explains why an internal concept representation arises in a prompt.
- CTA operates independently of whether the concept is expressed in the generated token.
- Cross-Layer Transcoders demonstrate that probe-targeted graphs contain predictive structure.
- Local features identify sparse components driving per-prompt classification.
- Causal ablations indicate that probe-targeted and logit-targeted graphs capture distinct functional mechanisms.
- Removing probe-relevant features reduces internal concept scores while largely preserving generated tokens.
Context
According to the authors, transcoder attribution graphs typically explain why a model assigns high probability to a particular next token. CTA shifts this focus by training attribution graphs with respect to a linear probe direction. This allows for the identification of probe-specific circuits that explain the emergence of internal concept representations. The framework uses Cross-Layer Transcoders to show that these probe-targeted graphs possess predictive structure, with graph-level features forecasting probe accuracy across four widely studied concept categories.
Why It Matters
This research provides a method for understanding the internal computations that enable linear probes to function. For researchers, it offers a way to connect probe performance to interpretable circuit structures, moving beyond simply knowing if a probe works to understanding how it works. This can inform the development of more transparent and reliable AI systems.
What To Do
- Review the paper's methodology for training attribution graphs with respect to linear probe directions.
- Note the findings from causal ablations regarding the distinct mechanisms captured by probe-targeted versus logit-targeted graphs.
- Consider how the Concept-Targeted Attribution framework could be applied to analyze internal concept representations in other model architectures.
