論文

第1 回・第2 回「ジェンダーと 教育を考える会」の記録 ―小平麻衣子先生と共に話し合うことから― より

感情という現象には表情や心拍数の変化などの身体反応が随伴する．このうち，自律神経系に関連する指標に，顔面皮膚血流（以下，顔血流）がある．顔血流は顔温度変化と顔色変化に関わる点で，従来の自律神経指標と異なる特徴をもつ．感情における顔血流の変動は，顔領域内で必ずしも一様な反応性を持たず，前額，頬，鼻などで特異的な変動パタンを有する場合がある．加えて，これまでは30秒程度以上の反応動態を解析することが多く，感情に関連する場面において5秒程度の急峻な反応の検討を進めることは，関連する精神疾患のメカニズム理解や臨床的介入に対する有益な示唆をもたらす可能性がある．

Facial skin blood flow (SkBF) has attracted attention as an autonomic indicator because it influences facial colour, which informs others of emotional states, and facial temperature related to social anxiety. Previous studies have examined the facial SkBF in people experiencing emotions; however, facial SkBF changes in the observers of emotions are poorly understood. Our study clarified facial SkBF changes related to observing others’ emotions by comparing the changes with other physiological indices. Thirty healthy participants (24 females; mean age: 22.17) observed six types of facial expressions (neutral, angry, and embarrassed expressions with and without facial blushing) and rated the emotional intensity of the other person. We measured their facial SkBF, finger SkBF, and cardiac RR interval as they made their observations. Facial SkBF generally decreased in relation to observing emotional faces (angry and embarrassed faces) and significantly decreased for angry expressions with blushing. None of the participants noticed blushing of facial stimuli. For the RR interval and finger SkBF, there was no variation depending on the observed facial expressions, although there was a general increase related to observation. These results indicated that facial SkBF is sensitive and reactive to emotional faces—especially angry faces with blushing— compared with other autonomic indices. The facial SkBF changes were not related to either RR interval changes or the intensity rating, suggesting that facial SkBF changes may be caused by vasoconstriction and have potential functions for our emotions. The decrease in facial SkBF may have a role in calming observers by preventing them from adopting the same emotional state as a person with intense anger. These findings clarify daily facial SkBF fluctuations and their relationship with our emotional processing in interpersonal situations.