People tend to perceive others' prosocial behavior as valuable and genuine when it is costly. Given that money (vs. time) is relatively scarcer for lower-class (vs. upper-class) people, we propose that the effect of target social class on others' prosocial intentions would vary across the donation and volunteering contexts. Specifically, we hypothesized that people would exhibit greater motivation to engage in prosocial behaviors when observing donation from lower-class targets than from those of upper-class, whereas the opposite would be the case for volunteering. The results across four studies (N = 984; Study 3 preregistered) supported our predictions. The predicted interaction effect between target social class and the type of prosocial behaviors emerged not only in participants' prosocial intentions (Studies 1–3), but also in their behavioral intentions (Study 4). Furthermore, the present research showed that perceived resource scarcity (Studies 2–4), self-reflection (Study 3), and genuineness (Study 4) served as significant mediators for the interaction effect between target social class and types of prosocial behaviors on participants' prosocial intentions.

人们倾向于认为他人的亲社会行为是有价值的和真诚的，但代价高昂。鉴于金钱（相对于时间）对于下层阶级（相对于上层阶级）的人来说相对稀缺，我们建议目标社会阶层对他人亲社会意图的影响在捐赠和志愿服务背景下会有所不同。具体来说，我们假设人们在观察来自下层目标的捐赠时会比来自上层目标的人表现出更大的参与亲社会行为的动机，而志愿服务的情况恰恰相反。四项研究的结果 ( N = 984; 研究 3 预注册）支持我们的预测。目标社会阶层与亲社会行为类型之间的预期交互作用不仅出现在参与者的亲社会意图（研究 1-3）中，而且出现在他们的行为意图中（研究 4）。此外，本研究表明，感知资源稀缺（研究 2-4）、自我反省（研究 3）和真实性（研究 4）是目标社会阶层与参与者亲社会行为类型之间相互作用的重要中介因素' 亲社会的意图。