Department of Psychotherapy and Psychosomatics, Medical Faculty, Technische Universität Dresden, Germany; Department of Pediatrics, Ev.-Luth. Diakonissenanstalt zu Flensburg, Germany.
Institute of Basic Medical Sciences, Department of Behavioural Medicine, Faculty of Medicine, University of Oslo, Norway.
Neuroscience. 2021 Jun 1;464:44-52. doi: 10.1016/j.neuroscience.2020.12.024. Epub 2020 Dec 29.
Slow stroking touch activates C-tactile (CT) fibres in the human skin and is typically described as pleasant. Over a longer duration of stroking, affective habituation sets in, indicated by a reduction in rated pleasantness. However, it is not clear whether the group level effect is represented on an individual level. We analyse the stability of individual ratings of slow stroking touch and their relationship to behavioural and physiological measures. Forty-eight participants (23 women) were repeatedly stroked with a velocity maximally activating CT fibres. The perceived pleasantness was rated on a visual analogue scale. In order to examine the stability of pleasantness ratings, the experiment was repeated after a couple of days. During the experiment, electrocardiogram (ECG) and facial-electromyography (EMG) data were recorded. On the group-level, previous results of affective habituation to touch were replicated and stable across sessions. On the individual level, however, less than half of the participants showed a significant reduction of pleasantness in the course of the experiment. Moreover, the remaining participants showed either no change, random rating behaviour or even an increase in pleasantness ratings during the course of the experiment. The individual response patterns were variable across sessions but stable above the chance level. Furthermore, the response patterns could not be explicitly associated with any of the behavioural or physiological measures. Our findings indicate a lack of group-to-individual generalizability for affective habituation to touch. The variability of rating patterns over time indicates that they are not conclusively determined by stable individual characteristics. Future research investigating touch should favour a more individual approach to the more commonly applied group analysis.
缓慢轻抚触感会激活人类皮肤中的 C 纤维（CT），通常被描述为愉悦。在较长时间的轻抚后，会出现情感适应，表现为愉悦感评分降低。然而，目前尚不清楚这种群体水平的效应是否在个体水平上得到体现。我们分析了个体对缓慢轻抚触感的评分稳定性及其与行为和生理测量的关系。48 名参与者（23 名女性）被以最大程度激活 CT 纤维的速度反复轻抚。他们使用视觉模拟量表对感知到的愉悦感进行评分。为了检验愉悦感评分的稳定性，实验在几天后重复进行。在实验过程中，记录了心电图（ECG）和面部肌电图（EMG）数据。在群体水平上，先前的触觉情感适应研究结果得到了重复验证，并且在各次实验中具有稳定性。然而，在个体水平上，不到一半的参与者在实验过程中表现出愉悦感明显降低。此外，其余参与者的表现要么是没有变化，要么是随机的评分行为，甚至在实验过程中表现出愉悦感评分增加。个体反应模式在各次实验中变化不定，但稳定高于随机水平。此外，这些反应模式无法明确与任何行为或生理测量相关联。我们的研究结果表明，触觉情感适应的群体到个体的可推广性较差。评分模式随时间的变化表明，它们不是由稳定的个体特征决定的。未来的触觉研究应更倾向于采用个体方法，而不是通常应用的群体分析方法。
