Trust in decision-making authorities dictates the form of the interactive relationship between outcome fairness and procedural fairness.

Reactions to decisions are shaped by both outcome and procedural fairness. Moreover, outcome and procedural fairness interact to influence beliefs and behaviors. However, different types of "process/outcome" interaction effects have emerged. Many studies have shown that people react particularly negatively when they receive unfair or unfavorable outcomes accompanied by unfair procedures (the "low-low" interactive pattern). However, others find that people react especially positively when they receive fair or favorable outcomes accompanied by fair procedures (the "high-high" interactive pattern). We propose that trust in decision-making authorities dictates the form of the process/outcome interaction. Across three studies, when trust was high, the "low-low" interactive pattern emerged. When trust was low, the "high-high" interactive pattern emerged. The findings suggest that when people's experience of outcome and procedural fairness diverged from how they expected to be treated, they reacted in the direction of their experiences; otherwise, their reactions were consistent with their expectations.