Kunz M, Lautenbacher S
Physiological Psychology, Otto-Friedrich University Bamberg, Germany; Biological Psychology, Ludwig Maximilian University, Munich, Germany.
Eur J Pain. 2014 Jul;18(6):813-23. doi: 10.1002/j.1532-2149.2013.00421.x. Epub 2013 Oct 31.
There is general agreement that facial activity during pain conveys pain-specific information but is nevertheless characterized by substantial inter-individual differences. With the present study we aim to investigate whether these differences represent idiosyncratic variations or whether they can be clustered into distinct facial activity patterns.
Facial actions during heat pain were assessed in two samples of pain-free individuals (n = 128; n = 112) and were later analysed using the Facial Action Coding System. Hierarchical cluster analyses were used to look for combinations of single facial actions in episodes of pain. The stability/replicability of facial activity patterns was determined across samples as well as across different basic social situations.
Cluster analyses revealed four distinct activity patterns during pain, which stably occurred across samples and situations: (I) narrowed eyes with furrowed brows and wrinkled nose; (II) opened mouth with narrowed eyes; (III) raised eyebrows; and (IV) furrowed brows with narrowed eyes. In addition, a considerable number of participants were facially completely unresponsive during pain induction (stoic cluster). These activity patterns seem to be reaction stereotypies in the majority of individuals (in nearly two-thirds), whereas a minority displayed varying clusters across situations.
These findings suggest that there is no uniform set of facial actions but instead there are at least four different facial activity patterns occurring during pain that are composed of different configurations of facial actions. Raising awareness about these different 'faces of pain' might hold the potential of improving the detection and, thereby, the communication of pain.
人们普遍认为，疼痛时的面部活动传达了特定于疼痛的信息，但个体之间仍存在很大差异。在本研究中，我们旨在调查这些差异是代表个体特异的变化，还是可以聚类为不同的面部活动模式。
在两组无痛个体样本（n = 128；n = 112）中评估热痛期间的面部动作，随后使用面部动作编码系统进行分析。分层聚类分析用于寻找疼痛发作时单个面部动作的组合。面部活动模式的稳定性/可重复性在不同样本以及不同基本社交情境中进行了测定。
聚类分析揭示了疼痛期间四种不同的活动模式，这些模式在不同样本和情境中稳定出现：（I）眼睛眯起、眉头紧皱且鼻子起皱；（II）嘴巴张开且眼睛眯起；（III）眉毛上扬；（IV）眉头紧皱且眼睛眯起。此外，相当数量的参与者在疼痛诱导期间面部完全无反应（坚忍型聚类）。这些活动模式在大多数个体中（近三分之二）似乎是反应定式，而少数个体在不同情境中表现出不同的聚类模式。
这些发现表明，不存在统一的面部动作组合，而是在疼痛期间至少有四种不同的面部活动模式，它们由不同的面部动作配置组成。提高对这些不同“疼痛表情”的认识可能具有改善疼痛检测以及进而改善疼痛交流的潜力。
