Surrogate Medical Choices Elevate Decision Thresholds and Tighten Gaze-Choice Coupling

Surrogate medical choices often favor life preservation over comfort, although the mechanisms underlying this tendency remain incompletely understood. We propose a prudence-implementation cascade in which assuming a surrogate role elevates decision thresholds and strengthens the coupling between attention and choice during evidence accumulation. In a within-subject eye-tracking experiment, participants chose between two-attribute treatment options contrasting expected survival with weekly burden for themselves versus an unfamiliar other. Under other-framing, comfort-favoring choices decreased and response times increased. Diffusion modeling indicated greater boundary separation, whereas non-decision time remained stable to slightly lower, consistent with strategic caution rather than generalized task difficulty. Eye-tracking analyses revealed a small but reliable attentional shift toward longevity-related information together with stronger gaze-choice coupling, such that momentary attention more strongly predicted choice outcomes. Brief exit interviews further converged on accountability-driven prudence and a preference for explicit survival evidence, complementing the quantitative findings. Collectively, the findings identify a coherent process signature of surrogate decision-making characterized by elevated thresholds, attentional prioritization of survival-related information, and stronger perception-action coupling. The results further suggest communication implications for preference-concordant care, including transparent presentation of treatment trade-offs and explicit clarification of patient values.