Shanghai Key Laboratory of Mental Health and Psychological Crisis Intervention, School of Psychology and Cognitive Science, East China Normal University, Shanghai, China.
Fralin Biomedical Research Institute, Virginia Tech, Roanoke, Virginia, United States of America.
PLoS Biol. 2024 Oct 8;22(10):e3002818. doi: 10.1371/journal.pbio.3002818. eCollection 2024 Oct.
Expectations shape our perception, profoundly influencing how we interpret the world. Positive expectations about sensory stimuli can alleviate distress and reduce pain (e.g., placebo effect), while negative expectations may heighten anxiety and exacerbate pain (e.g., nocebo effect). To investigate the impact of the (an)hedonic aspect of expectations on subjective experiences, we measured neurobehavioral responses to the taste of hot sauce among participants with heterogeneous taste preferences. By identifying participants who "liked" versus those who strongly "disliked" spicy flavors and by providing contextual cues about the spiciness of the sauce to be tasted, we dissociated the effects of positive and negative expectations from sensory stimuli (i.e., visual and gustatory stimuli), which were the same across all participants. Our results indicate that positive expectations lead to modulations in the intensity of subjective experience. These modulations were accompanied by increased activity in brain regions previously linked to information integration and the placebo effect, including the anterior insula, dorsolateral prefrontal cortex, and dorsal anterior cingulate cortex, as well as a predefined "pleasure signature." In contrast, negative expectations decreased hedonic experience and increased neural activity in the previously validated "Neurological Pain Signature" network. These findings demonstrate that hedonic aspects of one's expectations asymmetrically shape how the brain processes sensory input and associated behavioral reports of one's subjective experiences of intensity, pleasure, and pain. Our results suggest a dissociable impact of hedonic information: positive expectations facilitate higher-level information integration and reward processing, while negative expectations prime lower-level nociceptive and affective processes. This study demonstrates the powerful role of hedonic expectations in shaping subjective reality and suggests potential avenues for consumer and therapeutic interventions targeting expectation-driven neural processes.
期望塑造了我们的感知，深刻地影响着我们对世界的解释。对感官刺激的积极期望可以减轻痛苦和减少疼痛（例如，安慰剂效应），而消极期望可能会增加焦虑并加剧疼痛（例如，反安慰剂效应）。为了研究期望的愉悦方面对主观体验的影响，我们测量了具有不同味觉偏好的参与者对辣椒酱味道的神经行为反应。通过识别出“喜欢”和“强烈不喜欢”辣口味的参与者，并为要品尝的酱汁提供关于辣度的上下文线索，我们将积极和消极期望的影响与感官刺激（即视觉和味觉刺激）区分开来，这些刺激在所有参与者中都是相同的。我们的结果表明，积极的期望会导致主观体验强度的调节。这些调节伴随着与信息整合和安慰剂效应相关的大脑区域活动的增加，包括前岛叶、背外侧前额叶皮层和背侧前扣带皮层，以及预先定义的“愉悦特征”。相比之下，消极的期望会降低愉悦体验，并增加先前验证的“神经疼痛特征”网络中的神经活动。这些发现表明，期望的愉悦方面不对称地塑造了大脑如何处理感官输入以及相关的行为报告，这些报告涉及到强度、愉悦和疼痛的主观体验。我们的结果表明，愉悦信息具有可分离的影响：积极的期望促进了更高层次的信息整合和奖励处理，而消极的期望则启动了更低层次的伤害感受和情感过程。这项研究证明了愉悦期望在塑造主观现实方面的强大作用，并为针对期望驱动的神经过程的消费者和治疗干预提供了潜在途径。
