The role of personal values in opinion formation regarding a high-stakes continually evolving topic: The Hamas–Israel hostage deal negotiations.

= 7,248; four preregistered, one longitudinal) participated during the Hamas-Israel war, as hostage deal negotiations dominated public discourse. Universalism values predicted deal support, while power and tradition values predicted opposition. Values predicted opinions independently of demographics and empathy, with universalism significant even beyond political ideology. Opinion certainty was higher when values fit the opinion (e.g., high universalism coupled with support) than when they did not. A longitudinal design supported values' role in several ways. First, values measured before the first deal predicted opinions a year later. Second, low value coherence predicted change in opinion over time. Third, values predicted shifts in opinion over time. Finally, the fit between values and opinion predicted opinion stability through increased certainty. Although limited to a single sociopolitical context and lacking Palestinian perspectives, findings offer strong evidence that personal values may shape moral judgment under uncertainty and help individuals navigate evolving, emotionally charged dilemmas. The study offers new contributions by assessing values in relation to high-stakes (not hypothetical) dilemmas, tracking opinion change over a moving target (an evolving hostage deal), and demonstrating how value-opinion fit predicts opinion certainty and consequentially long-term stability. (PsycInfo Database Record (c) 2026 APA, all rights reserved).