CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain.
Óptica del Penedes Optometry Center, Zaragoza, Spain.
Ophthalmic Physiol Opt. 2022 Nov;42(6):1390-1398. doi: 10.1111/opo.13036. Epub 2022 Aug 12.
There is scientific evidence that an individual's beliefs and/or expectations play a role in the behavioural and physiological response to a given treatment. This study aimed to assess whether the dynamics of the accommodative response and stereoacuity are sensitive to experimentally induced placebo and nocebo effects.
Nineteen healthy university students performed three experimental sessions (placebo, nocebo and control) in randomised order, with the dynamics of the accommodative response (magnitude and variability), stereoacuity and subjective measures being assessed in all sessions. For the experimental manipulation, participants ingested an inert capsule that was alleged to have positive (white capsule, placebo condition) or negative (yellow capsule, nocebo conditions) effects on the human physiology. In the control condition, participants did not ingest a capsule.
The data revealed that the variability of accommodation was sensitive to experimentally induced placebo and nocebo effects, showing a more stable accommodative response for the placebo compared with the nocebo condition (corrected p-value = 0.04, Cohen's d = 0.60). In addition, better stereoacuity was found with the placebo, compared with the nocebo (corrected p-value = 0.01, Cohen's d = 0.69) and control (corrected p-value = 0.03, Cohen's d = 0.59) conditions. Successful experimental manipulation was confirmed by the analysis of subjective perceptions.
These findings provide evidence that manipulating expectations about the efficacy of an inert treatment affect the dynamics of the accommodative response (variability of accommodation) and stereoacuity. The results have important applications in both clinical and research outcomes, where individuals´ beliefs/expectations could modulate the visual function.
有科学证据表明，个体的信念和/或期望在对给定治疗的行为和生理反应中起作用。本研究旨在评估调节反应和立体锐度的动力学是否对实验诱导的安慰剂和反安慰剂效应敏感。
19 名健康的大学生以随机顺序进行了三个实验（安慰剂、反安慰剂和对照），在所有实验中评估调节反应（幅度和可变性）、立体锐度和主观测量的动态。对于实验操作，参与者服用了据称对人体生理学具有积极（白色胶囊，安慰剂条件）或消极（黄色胶囊，反安慰剂条件）影响的惰性胶囊。在对照条件下，参与者未服用胶囊。
数据显示，调节的可变性对实验诱导的安慰剂和反安慰剂效应敏感，与反安慰剂条件相比，安慰剂条件下的调节反应更稳定（校正后的 p 值=0.04，Cohen's d=0.60）。此外，与反安慰剂（校正后的 p 值=0.01，Cohen's d=0.69）和对照（校正后的 p 值=0.03，Cohen's d=0.59）条件相比，安慰剂条件下的立体锐度更好。通过主观感知分析证实了成功的实验操作。
这些发现提供了证据，证明操纵对惰性治疗效果的期望会影响调节反应（调节可变性）和立体锐度的动力学。这些结果在临床和研究结果中都有重要的应用，其中个体的信念/期望可以调节视觉功能。
