Quantifying Aleatoric Uncertainty of In-Context Learning for Robust Measure of LLM Prediction Confidence
Pith reviewed 2026-07-01 09:04 UTC · model grok-4.3
The pith
Self-function vectors enable direct estimation of aleatoric uncertainty in LLM in-context learning predictions.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Self-function vectors, constructed upon Bayesian views and the mechanistic interpretability of ICL, leverage internal model representations to model the latent concept learned during in-context prompting, thereby enabling a direct estimation of aleatoric uncertainty within a Bayesian framework.
What carries the argument
Self-function vectors that model the latent concept from in-context prompting using internal representations to estimate aleatoric uncertainty.
If this is right
- Aleatoric uncertainty in ICL predictions can be quantified separately from epistemic uncertainty.
- Uncertainty measurement becomes more reliable than methods that depend on brittle input or decoding manipulations.
- The method supports practical uses such as hallucination detection.
- The evaluation protocol isolates aleatoric uncertainty through controlled data manipulations on both synthetic and real datasets.
Where Pith is reading between the lines
- The connection between internal representations and uncertainty may extend to other prompting techniques beyond standard ICL.
- Improved aleatoric estimation could help distinguish data-inherent noise from model knowledge gaps in deployed systems.
- This framing suggests new ways to combine mechanistic analysis with quantitative uncertainty tools for few-shot reliability.
Load-bearing premise
Self-function vectors built upon Bayesian views and mechanistic interpretability of ICL can model the latent concept learned during in-context prompting to enable direct aleatoric uncertainty estimation.
What would settle it
A controlled experiment in which the method fails to report higher aleatoric uncertainty when label noise or input perturbations are systematically added to the demonstrations while holding model behavior fixed.
Figures
read the original abstract
In-Context Learning (ICL) allows LLMs to adapt to new tasks from a few demonstrations, but its reliability remains a concern: predictions are highly sensitive to both prompt design and the model's ability to understand the context, obscuring whether failures arise from data properties or model limitations. Uncertainty decomposition-separating aleatoric from epistemic sources-is particularly crucial in this setting, yet existing methods, designed for standard generation tasks, fail to capture the unique dynamics of ICL. To address this, we introduce a concept of self-function vectors, built upon Bayesian views and the mechanistic interpretability of ICL. These vectors leverage internal model representations to model the latent concept learned during in-context prompting, thereby enabling a direct estimation of aleatoric uncertainty within a Bayesian framework and circumventing the reliance on brittle input or decoding manipulations. Given the lack of established benchmarks and suitable evaluation protocols, we also propose the first and rigorous evaluation protocol, in which data is manipulated in controlled ways so as to quantify aleatoric uncertainty precisely and separately from epistemic uncertainty. With this new evaluation framework, initially grounded in synthetic tasks for conceptual development and subsequently extended to real-world datasets, we show that our proposed methodology can measure uncertainty of LLM predictions made under ICL more reliably than existing alternative methods. Moreover, we show it can be used as a practical tool for trustworthy-related applications, such as hallucination detection. Our findings pave a new direction for connecting the quantitative view of uncertainty with the mechanistic understanding of model behavior.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript introduces self-function vectors, constructed from internal LLM representations via Bayesian and mechanistic interpretability views of in-context learning (ICL), to enable direct estimation of aleatoric uncertainty in ICL predictions. It also proposes a new evaluation protocol using controlled data manipulations to isolate aleatoric uncertainty, reports superior performance over baselines on synthetic tasks and real-world datasets, and demonstrates utility for hallucination detection.
Significance. If the self-function vectors provably isolate aleatoric uncertainty without entanglement from epistemic sources, the work would meaningfully connect quantitative uncertainty estimation to ICL mechanics and supply a needed benchmark protocol. The protocol itself is a constructive contribution for future studies even if the vector method requires refinement.
major comments (2)
- [§3] §3: The definition of self-function vectors from internal activations provides no explicit invariance argument or derivation showing separation from epistemic factors (e.g., prompt sensitivity, model scale). Because the evaluation manipulations alter the same activations used to build the vectors, it is unclear whether reported gains reflect true aleatoric isolation or an artifact of incomplete separation.
- [Evaluation protocol] Evaluation protocol (synthetic and real-data sections): The claim that controlled manipulations quantify aleatoric uncertainty 'precisely and separately' from epistemic uncertainty lacks a formal argument or ablation demonstrating that the manipulations leave model parameters and prompt sensitivity unchanged while only varying data-inherent noise.
minor comments (2)
- [Abstract and §2] Abstract and §2: Include at least one key equation defining the self-function vector construction to allow readers to assess its Bayesian grounding without waiting for the full derivation.
- [Related-work section] Related-work section: Explicitly compare the proposed vectors against prior ICL uncertainty methods that also use internal states (e.g., attention or activation-based probes) to clarify novelty.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback, which identifies areas where additional formal justification would strengthen the manuscript. We respond to each major comment below.
read point-by-point responses
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Referee: [§3] §3: The definition of self-function vectors from internal activations provides no explicit invariance argument or derivation showing separation from epistemic factors (e.g., prompt sensitivity, model scale). Because the evaluation manipulations alter the same activations used to build the vectors, it is unclear whether reported gains reflect true aleatoric isolation or an artifact of incomplete separation.
Authors: We agree that the current manuscript lacks an explicit invariance argument or derivation. The self-function vectors are constructed from internal activations to capture the latent concept under a Bayesian view of ICL, with the intent that averaging over in-context examples isolates data-inherent (aleatoric) variation while epistemic factors are reflected in model-scale or prompt variations. However, this separation is not formally derived. In revision we will add a subsection deriving the invariance properties under the stated Bayesian and mechanistic assumptions, and include new ablations that vary prompt phrasing and model scale while holding data noise fixed, to test whether the uncertainty estimates remain stable. revision: yes
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Referee: [Evaluation protocol] Evaluation protocol (synthetic and real-data sections): The claim that controlled manipulations quantify aleatoric uncertainty 'precisely and separately' from epistemic uncertainty lacks a formal argument or ablation demonstrating that the manipulations leave model parameters and prompt sensitivity unchanged while only varying data-inherent noise.
Authors: The protocol manipulates only the data (e.g., controlled label or input noise) while keeping the model, task definition, and prompt template fixed, with the goal of varying only aleatoric sources. We acknowledge that the manuscript provides neither a formal argument nor targeted ablations confirming that model parameters and prompt sensitivity remain unchanged. In the revision we will add (i) a formal statement of the assumptions under which the manipulations affect only data-inherent noise and (ii) an ablation that measures prompt sensitivity and cross-model consistency before and after each manipulation, reporting that the aleatoric estimates track the introduced noise level independently of these factors. revision: yes
Circularity Check
No circularity: derivation chain not exhibited in text
full rationale
The provided abstract and reader summary contain no equations, no explicit derivation steps, and no self-citations that could be inspected for reduction to inputs. Self-function vectors are described at a high level as built on Bayesian views and ICL interpretability to estimate aleatoric uncertainty, but without any mathematical construction shown, no self-definitional, fitted-input, or self-citation load-bearing pattern can be identified. The evaluation protocol is presented as a new contribution rather than a renaming or smuggling of prior results. The paper is therefore self-contained against external benchmarks on the basis of the given text; a score of 0 is the appropriate default when no load-bearing step reduces by construction.
Axiom & Free-Parameter Ledger
invented entities (1)
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self-function vectors
no independent evidence
Reference graph
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