Moral Concern Is a Response Regime: A Preregistered Cross-Model Test of Persona Framing in Large Language Models
Four large language models from four providers judged the same 20 ambiguous scenarios under a neutral frame and six loaded personas, across 11,200 main trials. The prediction came from Motivated Violation Construction (MVC), a theory of human moral cognition on which a loaded actor identity can move ambiguous behaviour into the violation category. A registered test-retest gate fixed the confirmatory panel, and semantically inert stimuli tested for frame-driven responding with no behaviour to classify. The models occupied sharply different operating ranges. Two classified almost every scenario as concerning under the neutral frame, leaving little headroom for the predicted increase, and one failed the correlation-based stability gate under near-ceiling responding. Across the retained three-model panel, none of four MVC predictions was supported, and the registered adjudication favoured valence priming over construction. On inert stimuli, three models almost never expressed concern, while one did so on roughly a third of trials and more often under loaded personas. The transfer test was therefore not supported. Whether that is also a refutation turns on detectability, which differed sharply across the retained panel. The durable result is a measurement result. Baseline, headroom, retest behaviour, sensitivity to prompt position and wording, refusal and missingness, and false entry on inert stimuli all differed by model. We call that configuration a model’s response regime, and it meant the same forced question carried different information in each system. A shared prompt is not a shared instrument, and a forced moral verdict measures the regime before it measures anything moral.