If you are trying to persuade someone, expressing your opinion with certainty intuitively seems like a good strategy to maximize your influence. However, Karmarkar and Tormala (2010) found that the effectiveness of this tactic depends on expertise. In three experiments, Karmarkar and Tormala found support for an incongruity hypothesis, whereby non-expert sources can gain interest and influence by expressing certainty, while expert sources can increase persuasion by expressing uncertainty. In this Registered Report, we conducted a high-powered ( = 1018) direct replication of Experiment 2 by Karmarkar and Tormala (2010). In a consumer behaviour context, the original study examined whether source expertise moderated the positive effect of source certainty on the persuasive impact of a restaurant recommendation. The present replication failed to find support for the incongruity hypothesis, = 0.00 [0.00, 0.02]: expressing certainty had a positive but non-significant effect for non-experts, = 0.10 [−0.10, 0.34], and a positive effect for experts, = 0.28 [0.03, 0.52]. Instead, the results supported the competing hypothesis that expressed certainty would have a positive effect on persuasion, irrespective of source expertise, = 0.18 [0.01, 0.36]. Extending the original work, we (1) controlled for the reason given for (un)certainty, and (2) examined need for closure as a potential individual difference moderator. The results indicated robust support for the confidence heuristic = 0.25, [0.12, 0.37], but neither reason for (un)certainty nor need for closure moderated the effect as hypothesized. All materials, data, and code are available on: .

中文翻译：

---

不确定性、专业知识和说服力：复制和扩展


如果你想说服某人，直观地表达你的观点似乎是最大化你的影响力的好策略。然而，Karmarkar 和 Tormala (2010) 发现这种策略的有效性取决于专业知识。在三个实验中，卡马卡和托马拉发现了对不协调假设的支持，即非专家来源可以通过表达确定性来获得兴趣和影响力，而专家来源可以通过表达不确定性来增加说服力。在这份注册报告中，我们对 Karmarkar 和 Tormala (2010) 的实验 2 进行了高效 (= 1018) 直接复制。在消费者行为背景下，最初的研究考察了来源专业知识是否调节了来源确定性对餐厅推荐的说服力的积极影响。目前的复制未能找到对不一致假设的支持，= 0.00 [0.00, 0.02]：表达确定性对非专家有积极但不显着的影响，= 0.10 [−0.10, 0.34]，对专家有积极影响, = 0.28 [0.03, 0.52]。相反，结果支持了相互竞争的假设，即无论来源专业知识如何，表达的确定性都会对说服力产生积极影响，= 0.18 [0.01, 0.36]。扩展原始工作，我们（1）控制了给出的（不确定）确定性的原因，并且（2）检查了作为潜在个体差异调节器的封闭的需要。结果表明对置信启发式 = 0.25, [0.12, 0.37] 的有力支持，但无论是（不确定）的原因还是关闭的需要都没有像假设的那样调节效果。所有材料、数据和代码均可在以下位置获取： 。