Swaddle J P, Cuthill I C
Behavioural Biology Group, School of Biological Sciences, University of Bristol, U.K.
Proc Biol Sci. 1995 Jul 22;261(1360):111-6. doi: 10.1098/rspb.1995.0124.
It has been postulated that levels of fluctuating asymmetry in human faces may be negatively related to components of fitness such as parasite-resistance; hence potential mates with low levels of asymmetry may appear more attractive. However, previous investigations of the relationship between asymmetry and facial attractiveness have confounded manipulations of asymmetry with facial 'averageness' and mean trait size. In this experiment we performed a manipulation that altered asymmetry within a face without altering the mean size of facial features. These faces were then rated on attractiveness. Contrary to what was predicted, faces that were made more symmetrical were perceived as being less attractive. These results do not support the hypothesis that attractiveness is related to low levels of fluctuating asymmetry. The observed positive relationship between asymmetry and facial attractiveness may be because certain facial features (including those contributing to attractiveness) in fact show directional asymmetry or antisymmetry. Our manipulations thus render naturally asymmetric features symmetrical. This may make symmetric faces less attractive because of the reduction of natural directional asymmetries, perhaps making the faces appear unemotional. The role of fluctuating asymmetries alone in assessments of facial beauty is still unknown, although this experiment suggests fluctuating asymmetry is relatively unimportant compared with directional asymmetry.
据推测，人类面部波动不对称的程度可能与诸如抗寄生虫能力等健康因素呈负相关；因此，不对称程度低的潜在配偶可能看起来更有吸引力。然而，先前关于不对称与面部吸引力之间关系的研究将不对称的操纵与面部“平均性”和平均特征大小混淆了。在本实验中，我们进行了一项操纵，改变面部内部的不对称性，而不改变面部特征的平均大小。然后对这些面部的吸引力进行评分。与预测相反，变得更对称的面部被认为吸引力较低。这些结果不支持吸引力与低水平波动不对称相关的假设。观察到的不对称与面部吸引力之间的正相关关系可能是因为某些面部特征（包括那些有助于吸引力的特征）实际上表现出定向不对称或反对称。因此，我们的操纵使自然不对称的特征变得对称。这可能会使对称面部的吸引力降低，因为自然定向不对称性的减少，也许会使面部显得没有情感。仅波动不对称在面部美评估中的作用仍然未知，尽管本实验表明，与定向不对称相比，波动不对称相对不太重要。
