Rewarded placebo analgesia: A new mechanism of placebo effects based on operant conditioning
Rewarded placebo analgesia: A new mechanism of placebo effects based on operant conditioning
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DOI：
10.1002/ejp.1360
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发表时间：
2019-05-01
影响因子：
3.6
通讯作者：
Babel, Przemyslaw
中科院分区：
文献类型：
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作者：
Adamczyk, Waclaw M.;Wiercioch-Kuzianik, Karolina;Babel, Przemyslaw
背景安慰剂镇痛可以用两种学习过程来解释：经典条件反射和观察学习。第三个学习过程，操作性条件反射，以前没有被研究作为安慰剂效应的机制。我们的目的是通过操作性条件反射诱导安慰剂镇痛。方法三组受试者接受相同强度的皮肤电刺激，之前是橙子或蓝色刺激。在研究的条件反射阶段，实验组的参与者在一种颜色刺激（安慰剂）后的低疼痛反应和在另一种颜色刺激（非安慰剂）后的高疼痛反应得到奖励。此外，当他们的疼痛反应在安慰剂刺激后高而在非安慰剂刺激后低时，他们会受到惩罚。随机对照组以非权变的方式接受奖励和惩罚，以探讨权变的作用，即奖励/惩罚与疼痛反应之间的依赖关系。颜色控制组没有接受任何奖励或惩罚来控制非联想学习。疼痛强度等级被用作结果测量，疼痛等级的口头反馈被用作奖励/惩罚者。结果当停止奖励和惩罚时，只有实验组的参与者在安慰剂刺激后比在非安慰剂刺激后感受到更少的疼痛，即在该组中发现安慰剂镇痛。这种影响在研究过程中没有消失。结论操作性条件反射可诱导安慰剂镇痛，这是产生安慰剂效应的第三种机制。此外，疼痛反应和奖励/惩罚者之间的偶然性是通过操作性条件反射诱导安慰剂镇痛的关键。根据目前的安慰剂文献，安慰剂镇痛可以通过两个学习过程来解释：经典条件反射和观察学习。第三个学习过程，操作性条件反射，以前没有被研究作为安慰剂效应的机制。我们的研究表明，患者可以学习安慰剂镇痛作为操作性条件反射的结果，这表明随机对照试验可以通过控制强化来改善，这种强化可能在患者与例如医务人员互动时自发发生。
Background Placebo analgesia is explained by two learning processes: classical conditioning and observational learning. A third learning process, operant conditioning, has not previously been investigated as a mechanism of placebo effects. We aimed to induce placebo analgesia by operant conditioning. Methods Three groups of participants received electrocutaneous pain stimuli of the same intensity, preceded by either an orange or blue stimulus. In the conditioning phase of the study, participants from the experimental group were rewarded for low pain responses following one of the colour stimuli (placebo) and for high pain responses following the other colour stimuli (non-placebo). Moreover, they were punished when their pain responses were high following placebo stimuli and low following non-placebo stimuli. To investigate the role of contingency, that is dependent relation between rewards/punishers and pain responses, the random-control group received rewards and punishers in a non-contingent manner. The colour-control group did not receive any rewards or punishers to control for nonassociative learning. Pain intensity ratings were used as an outcome measure, and verbal feedback on pain ratings was used as rewards/punishers. Results When rewarding and punishment were stopped, only participants from the experimental group experienced less pain following the placebo than following the non-placebo stimuli; that is, placebo analgesia was found in this group. This effect was not extinguished during the study. Conclusions Placebo analgesia can be induced by operant conditioning, which should be considered a third mechanism for producing placebo effects. Moreover, the contingency between pain responses and rewards/punishers is crucial to induce placebo analgesia through operant conditioning. Significance According to the current placebo literature, placebo analgesia can be explained by two learning processes: classical conditioning and observational learning. A third learning process, operant conditioning, has not previously been investigated as a mechanism of placebo effects. Our study reveals that patients can learn placebo analgesia as a result of operant conditioning, suggesting that randomized controlled trials could be improved by controlling the reinforcement that might occur spontaneously when patients interact with, for example, medical personnel.