Pain expression and decoding as intergroup phenomena.

Pain is a highly subjective sensory and emotional experience. Mirroring basic emotions (e.g., sadness, anger) - pain can be characterized by a prototypical expression (e.g., lowering of the eyebrows, squeezing of the eyes, wrinkling of the nose, raising of the upper lip, and opening of the mouth) and can be distinguished from a variety of other emotional expressions. However, the pain expression is uniquely powerful in communicating a need for help and eliciting empathy-related responses (e.g., neural responses), both of which are deeply intertwined with intergroup dynamics. We propose a framework for considering pain as an intergroup expression, including an illustration of how intergroup contexts impact pain facial expression, decoding, and observer action which reciprocally inform one-another. The current work reviews existing work on observers' decoding facial expressions of pain (via neural responses, recognition performance, authenticity detection, and expression intensity judgments) and expressors' expression of pain-with a focus on understanding the role of intergroup dynamics in the decoding and expression of pain through the face. Through this review, we identify new directions for advancing work at the intersection of pain science and intergroup relations.