Campbell R
Cortex. 1979 Dec;15(4):571-9. doi: 10.1016/s0010-9452(79)80046-5.
Asymmetries in the expression of a posed smile and in a relaxed facial expression were observed in 24 left-handers. Neither writing position nor familial sinistrality predicted the variance of the results. Left-handers were found to smile more with their left than right side of face; an asymmetry which had previously been observed in right-handers. If anything, left-handers' smiles were more asymmetric, though in the same direction, than right-handers. When relaxed, however, the left-handers' face was judged more unhappy on its right than left side--a reversal of the direction of asymmetry previously noted in right-handers' relaxed expressions. No single neurological or psychological theory accounts for these results; it is suggested that hand preference may exert a myotonic effect which is reflected in judgements of relaxed facial expressions.
在24名左利手者中观察到了 posed 微笑和放松面部表情表达上的不对称。书写姿势和家族性左利手都无法预测结果的差异。发现左利手者用左脸比右脸笑得更多；这种不对称先前在右利手者中也有观察到。如果有什么不同的话，左利手者的微笑比右利手者更不对称，尽管方向相同。然而，当处于放松状态时，左利手者的右脸被判定比左脸更显不悦——这与先前在右利手者放松表情中所观察到的不对称方向相反。没有单一的神经学或心理学理论能够解释这些结果；有人提出，用手偏好可能会产生一种强直性效应，这种效应反映在对放松面部表情的判断中。
