User expectations impact the evaluation of new interactive systems. Elevated expectations may enhance the perceived effectiveness of interfaces in user studies, similar to a placebo effect observed in medical studies. To showcase the placebo effect, we executed a user study with 18 participants who conducted a reaction time test with two different computer screen refresh rates. Participants saw a stated screen refresh rate before every condition, which corresponded to the true refresh rate only in half of the conditions and was lower or higher in the other half. Results revealed successful priming, as participants believed in superior or inferior performance based on the narrative despite using the opposite refresh rate. Post-experiment questionnaires confirmed participants still held onto the initial narrative. Interestingly, the objective performance remained unchanged between both refresh rates. We discuss how study narratives can influence subjective measures and suggest strategies to mitigate placebo effects in user-centered study designs.

翻译：用户期望会影响对新型交互系统的评估。在用户研究中，提升的期望可能会增强界面的感知有效性，类似于医学研究中的安慰剂效应。为展示安慰剂效应，我们进行了一项用户研究，18名参与者分别在两种不同计算机屏幕刷新率下完成反应时间测试。参与者在每种条件前都会看到标明的屏幕刷新率，仅在一半的条件中该标明值与实际刷新率一致，另一半则偏高或偏低。结果表明启动效应成功实现：尽管实际采用了相反的刷新率，参与者仍基于说明信息相信自身表现更优或更差。实验后问卷证实参与者仍固守初始说明。值得注意的是，两种刷新率下的客观表现并未改变。我们讨论了研究说明如何影响主观测量指标，并提出了在用户中心研究设计中缓解安慰剂效应的策略。