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arxiv: 2607.00937 · v1 · pith:MNYS74RDnew · submitted 2026-07-01 · 💻 cs.CL

Persona Non Grata: LLM Persona-Driven Generations in MCQA are Unstable in Distinct Dimensions

Pith reviewed 2026-07-02 13:04 UTC · model grok-4.3

classification 💻 cs.CL
keywords persona-driven generationsMCQAinstability metricsLLM consistencyprompt formatmodel familiesquestion domainstask accuracy
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The pith

LLM persona-driven generations in multiple-choice question answering exhibit instability across performance, outcome, and question correctness that varies by model family, size, domain, and prompt format.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper develops three metrics to track distinct kinds of instability when large language models adopt personas while answering multiple-choice questions. Evaluation across models and tasks shows that instability is not uniform: it differs reliably between model families and sizes, rises for math and commonsense items, and responds more to task prompt format than to temperature. Because persona-driven generations are already common in research and applications, these patterns indicate that reliability cannot be assumed and that the most effective persona can change with small experimental choices.

Core claim

Persona-driven generations in MCQA are unstable in three distinct dimensions measured by performance stability, outcome stability, and question correctness stability. This instability varies consistently between model families and model sizes, is greater for math and commonsense questions, is more strongly affected by task prompt format than by other hyperparameters such as temperature, correlates with lower task accuracy, and produces different best and worst personas under different experimental settings.

What carries the argument

Three metrics—performance stability, outcome stability, and question correctness stability—that quantify separate dimensions of how persona assignments alter LLM predictions on multiple-choice items.

If this is right

  • Math and commonsense questions produce greater instability than other domains.
  • Task prompt format drives more prediction instability than temperature.
  • Higher instability is associated with lower overall task accuracy.
  • Different hyperparameter settings yield different rankings of best and worst personas for the same task.
  • Hyperparameter instability must be checked when selecting personas for MCQA.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Users of persona methods in MCQA should test multiple prompt formats rather than relying on a single setting.
  • The stability metrics could be applied to non-MCQA tasks to check whether domain effects generalize.
  • Model choice for persona applications should weigh family-level and size-level consistency differences.

Load-bearing premise

The three metrics capture the relevant dimensions of instability without missing major failure modes or depending too heavily on arbitrary persona definitions and question selections.

What would settle it

A replication that finds prompt format does not increase instability more than temperature, or that math and commonsense questions do not show reliably higher instability than other domains under the same metrics, would falsify the central patterns.

Figures

Figures reproduced from arXiv: 2607.00937 by C\'esar Guerra-Solano, Xiang Lorraine Li.

Figure 1
Figure 1. Figure 1: Depicting instability in non-text-heavy persona-driven generations (PDGs). Given different, al￾though still reasonable, experiment configurations, rep￾resented by different settings for the task prompt format (TPF) hyperparameter, an LLM’s persona-driven perfor￾mance on a multiple-choice evaluation differs greatly. teacher. Explain [...]") or more specific task com￾pletion (e.g. "You are a hiring manager. … view at source ↗
Figure 2
Figure 2. Figure 2: A figure depicting how instability metrics are calculated based on PDGs for our dataset. Across runs in [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: A figure depicting the delta hyperparameter instability of temperature (Temp.), persona prompt format [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Depicting the delta hyperparameter instability [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Depicting the delta hyperparameter instability of Temp., PPF, and TPF compared to the baseline. "Dataset" [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: An example of different experimental out [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: A figure depicting the delta hyperparameter [PITH_FULL_IMAGE:figures/full_fig_p015_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Instability results stratified by instability metric, by dataset category, by persona sub-category. [PITH_FULL_IMAGE:figures/full_fig_p017_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: All classifier performances when trained across 48 experimental settings, additionally stratified by specific [PITH_FULL_IMAGE:figures/full_fig_p017_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Comparing instability results across different formulations of [PITH_FULL_IMAGE:figures/full_fig_p019_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Hyperparameter instability results per metric, per model, stratified by dataset category and persona [PITH_FULL_IMAGE:figures/full_fig_p023_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: All inter-persona performance distributions between the "unstable" and "stable" experiment settings, as [PITH_FULL_IMAGE:figures/full_fig_p023_12.png] view at source ↗
read the original abstract

Persona-driven generations (PDGs) have seen prolific use in research and industry applications, where a large language model (LLM) takes on a 'persona' while completing some task. While persona expressed through free-form text (like dialogue) has substantial work investigating stability or consistency, relatively, persona expressed in non-text-heavy outputs (like in multiple-choice question answering, or MCQA) is often overlooked. We work to address this gap, seeking to understand the instability of LLM PDGs in MCQA tasks. We develop three metrics investigating the performance, outcome, and question correctness stability, evaluating three distinct dimensions. Using these metrics, we find that instability varies consistently between model families and model size, and across question domains, with math/commonsense questions leading to greater instability. We also find task prompt format introduces more prediction instability than other hyperparameters, like temperature. Finally, we find that instability is related to task accuracy, and using our instability metrics, find different experimental settings that result in different best and worst personas for tasks, despite their similarity. This reveals the importance of checking hyperparameter instability in PDGs.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The manuscript empirically studies instability in LLM persona-driven generations (PDGs) for MCQA tasks. It defines three metrics capturing performance stability, outcome stability, and question-correctness stability, then reports that instability varies consistently by model family and size, is higher for math/commonsense domains than others, is more affected by task prompt format than by temperature, correlates with task accuracy, and produces different best/worst personas across experimental settings.

Significance. If the central claims hold after robustness verification, the work usefully distinguishes three dimensions of PDG instability and supplies concrete evidence that prompt format dominates other hyperparameters. This could inform more reliable use of personas in MCQA applications. The explicit comparison of instability across domains and the observation that optimal personas shift with settings are practical contributions, though the lack of checks on metric sensitivity to arbitrary persona and question choices limits immediate generalizability.

major comments (1)
  1. [§3 and §4] §3 (Metrics) and §4 (Experiments): the three stability metrics are defined and applied without any reported sensitivity analysis to persona phrasing, number of personas per category, or question sampling criteria. Because the claims of consistent patterns across model families, sizes, and domains (math/commonsense showing greater instability) rest on these metrics reflecting intrinsic properties rather than sampling artifacts, this is a load-bearing gap.
minor comments (2)
  1. [Abstract] Abstract: quantitative results, error bars, dataset sizes, and exclusion criteria are omitted, making it hard to gauge the strength of the reported patterns on first reading.
  2. [Experimental Setup] Ensure all model versions, exact prompt templates, and the full list of personas are provided in an appendix or repository to support reproducibility.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their constructive comments on our work. The major concern identifies a gap in sensitivity analysis for the stability metrics. We address this point directly below and agree that additional verification will improve the manuscript.

read point-by-point responses
  1. Referee: [§3 and §4] §3 (Metrics) and §4 (Experiments): the three stability metrics are defined and applied without any reported sensitivity analysis to persona phrasing, number of personas per category, or question sampling criteria. Because the claims of consistent patterns across model families, sizes, and domains (math/commonsense showing greater instability) rest on these metrics reflecting intrinsic properties rather than sampling artifacts, this is a load-bearing gap.

    Authors: We agree that the manuscript does not report sensitivity analyses varying persona phrasing, the number of personas per category, or question sampling criteria. The experiments used fixed but diverse persona sets and question samples drawn from established benchmarks, and the observed patterns (e.g., higher instability in math/commonsense domains, prompt format effects) were consistent across multiple model families and sizes. This provides indirect support that the metrics capture systematic differences rather than artifacts. Nevertheless, we recognize that explicit checks would strengthen the claims against sampling concerns. In the revised version we will add a dedicated subsection to §4 that reports results from (i) rephrased persona prompts, (ii) different numbers of personas per category, and (iii) alternative question sampling procedures, confirming that the main patterns remain stable. revision: yes

Circularity Check

0 steps flagged

No significant circularity; empirical metrics and observations are self-contained

full rationale

This is an empirical study that defines three stability metrics (performance, outcome, question-correctness) explicitly at the outset and reports observed patterns across model families, sizes, domains, and hyperparameters. No equations, derivations, or predictions are present that reduce results to fitted inputs by construction, and no self-citation chains or uniqueness theorems are invoked as load-bearing premises. The central claims rest on direct measurement rather than any self-referential reduction, satisfying the criteria for a non-circular empirical analysis.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Central claim rests on empirical observations from LLM experiments; no free parameters, invented entities, or non-standard axioms are introduced.

axioms (1)
  • domain assumption LLMs respond to persona instructions in free-form text prompts
    Foundational setup for all persona-driven generation experiments.

pith-pipeline@v0.9.1-grok · 5729 in / 1098 out tokens · 24118 ms · 2026-07-02T13:04:16.989782+00:00 · methodology

discussion (0)

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Reference graph

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