Methods · Training Data Attribution

Influence Functions (Gradient-Based Attribution)

Survey sections: §11.2 Gradient-Based Attribution: Understanding Data Influence Through Perturbations · §11.2.1 Core Idea: Parameter Response to Training Data · §11.2.2 Proximal Bregman Response and the Generalised Gauss–Newton · §11.2.3 Addressing the Computational and Memory Bottlenecks of GGN · §11.2.6 Illustrative Example · §11.2.7 Recent Extensions and Limitations

Influence functions estimate how a model’s parameters and predictions would change if a training sample were slightly upweighted (Koh & Liang, 2017; Grosse et al., 2023).

Assumptions and requirements

Empirical results show that the original form of influence functions introduced above performs poorly in practice. This is due to multiple assumptions that rarely hold in practice.
One classical approach is called the proximal Bregman response function (PBRF) (Bae et al., 2022). It targets model parameters which minimise the new training objective while staying close to the original parameters.
Although K-FAC approximates the FIM rather than the GGN, these matrices are equivalent for common loss functions under suitable probabilistic assumptions.

Evaluation considerations

Influence functions identify training documents that impacted the translation, even without exact verbatim matches. This demonstrates that gradient-based methods can capture influences beyond what verbatim methods can reveal.
Bae et al. (2022) confirmed empirically that such influence estimates align well with the actual PBRF.

Intended applications

Training data attribution (TDA) shifts the focus from model internals to training data, searching for training samples that strongly shaped the model behaviour.
TDA applications include, but are not limited to, identifying influential training samples, detecting train–test leakage, and diagnosing model failures without retraining (Liu et al., 2025a; Park et al., 2023; Grosse et al., 2023).
Although TDA is not generally a mechanistic method under this survey’s criteria, it can complement mechanistic interpretability in many ways. For example, by revealing how specific training samples shape malicious behaviour, TDA can enable effective training data filtering to prevent unwanted behaviours or even their internal mechanisms from forming during the training of next-generation models.

Limitations

(2026) introduced Concept Influence to enable attribution at the level of semantic concepts represented by model internals such as sparse autoencoder features. This brings TDA closer to the mechanistic goal of understanding how training data shapes specific internal computations. However, fundamental technical challenges persist, including approximation errors that compound over the training trajectory, variability across training runs caused by randomness like data ordering, and memory and computational bottlenecks of scaling to frontier models.
Token-level filtering is motivated by data attribution, but it remains unclear whether methods such as influence functions (Section 11) can reliably identify the relevant data.

Related methods

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Key papers

Cited in §11.2.

Also discussed in: §1.2 Survey Scope · §11 Training Data Attribution · §11.2.6 Observation · §11.2.7 Summary · §10.4.2 Open Questions

Other methods in Training Data Attribution

Verbatim Data Attribution: OLMoTrace · Kronecker-Factored Approximate Curvature (K-FAC) · Eigenvalue-Corrected K-FAC (EK-FAC) and ASTRA · TRAK (Tracing with the Randomly-projected After Kernel) · TracIn