An unpleasant context (bitter aftertaste) is able to reduce the late positive potential (LPP) elicited by affective pictures. This study attempted to influence this context with a placebo. Sixty-eight women were randomly assigned to three groups: Water, Bitter/No-Placebo, Bitter/Placebo. Participants in the 'bitter groups' first rinsed their mouth with wormwood tea that caused a bitter aftertaste. Subsequently, the placebo group received sham light therapy on the tongue to 'reduce the sensitivity of the taste buds'. All groups viewed disgusting and non-disgusting pictures while their electroencephalogram was recorded. The Bitter/Placebo group reported reduced bitterness and disgust for the aftertaste after the sham treatment. The LPP reduction (300-600 ms after picture onset) associated with the bitter aftertaste (as shown by the Bitter/No-Placebo group) was attenuated due to the placebo treatment. This is the first EEG study to demonstrate that a context-targeting placebo is able to change automatic attention allocation.

中文翻译：

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安慰剂可以改变情感环境：与事件相关的潜在研究

令人不快的环境（苦涩的回味）能够减少由情感图片引起的晚期正电位（LPP）。这项研究试图用安慰剂来影响这种情况。68 名女性被随机分配到三组：水、苦味/无安慰剂、苦味/安慰剂。“苦味组”的参与者首先用艾草茶漱口，这会产生苦涩的余味。随后，安慰剂组在舌头上接受了假光疗法，以“降低味蕾的敏感性”。所有组在记录脑电图的同时观看恶心和非恶心的图片。苦味/安慰剂组报告了在假处理后苦味和对余味的厌恶减少。由于安慰剂治疗，与苦味回味（如苦味/无安慰剂组所示）相关的 LPP 减少（图片开始后 300-600 毫秒）减弱。这是第一项证明上下文靶向安慰剂能够改变自动注意力分配的脑电图研究。