Leader expressed humility (LEH) is an interpersonal, positive leader behavior that involves appreciating the strengths and contributions of others, recognizing one's own weaknesses, and being teachable. Investigating boundary conditions, our research juxtaposes LEH with followers' competitiveness, an indiscriminate need to compete and win at any cost. Employing social exchange theory, we theorize how follower competitiveness potentially impacts the positive effects of leader expressed humility on followers' affective trust in the leader and subsequent turnover. We examine our proposed moderated-mediation model with data from employees working in various German industries in two studies: a field study (Study 1) with four measurement points (time points 1–3 were separated by 1-month intervals and Time 4 followed 14 months after Time 2) and an experimental scenario study (Study 2). Results show (a) followers' competitiveness to weaken the effect of leaders' expressed humility on followers' affective trust in the leader as well as (b) indirect effects on followers' intended and actual, voluntary turnover. Notably, a consistent interaction pattern emerged across the two studies demonstrating that low (but not high) leader humility has divergent effects on followers as a function of followers' levels of competitiveness. From these results, we develop novel insights into the role of personality variables in social exchange processes and propose a minor extension of social exchange theory.

领导者表达的谦逊 (LEH) 是一种人际交往、积极的领导行为，包括欣赏他人的长处和贡献、承认自己的弱点以及受教。通过调查边界条件，我们的研究将 LEH 与追随者的竞争力并列，即不分青红皂白地需要不惜一切代价竞争和取胜。运用社会交换理论，我们理论化了追随者竞争力如何潜在地影响领导者表达谦逊对追随者对领导者的情感信任和随后的离职的积极影响。我们在两项研究中使用来自德国各个行业的员工的数据检查了我们提出的适度调解模型：具有四个测量点的实地研究（研究 1）（时间点 1-3 间隔 1 个月，时间 4 在时间 2 之后的 14 个月后进行）和实验情景研究（研究 2）。结果表明（a）追随者的竞争力削弱了领导者表达的谦逊对追随者对领导者的情感信任的影响，以及（b）对追随者的预期和实际自愿离职的间接影响。值得注意的是，在这两项研究中出现了一致的互动模式，表明低（但不高）领导者谦逊对追随者的影响是不同的，这是追随者竞争力水平的函数。根据这些结果，我们对人格变量在社会交换过程中的作用提出了新的见解，并提出了社会交换理论的一个小扩展。