Perhaps the most famous theory, the study of body movement, was suggested by Professor Ray Birdwhistell. He believes that physical appearance is often culturally programmed. In other words, we learn our looks — we are not born with them.
A baby has generally informed face features. A baby, according to Birdwhistell, learns where to set the eyebrows by looking at those around — the family and friends. This helps explain why the people of some areas of the US look so much alike.
New Englanders or Southerners have certain common face features that cannot be explained by genetics (遗传学) . The exact shape of the mouth is not set at birth. It is learned after. In fact, the final mouth shape is not formed until well after new teeth are set. For many people, this can be well into their childhood. A husband and wife who have lived together for a long time often come to look somewhat alike. We learn our looks from those around us .
This is perhaps why in a single country there are areas where people smile more than those in other areas. In the US, for example, the south is the part of the country where people smile most frequently. In New Zealand they smile less, and in the western part of New York people are considered unfriendly, partly because people in Madison Avenue smile less than people on Peachtree Street in Atlanta, Georgia. People in largely populated areas also smile and greet each other in public less than people in small towns do.

　　也许，有关肢体动作研究的最著名理论是由雷伊·伯德威斯泰尔教授提出来的。他认为，人的外表常常是由文化所设定的，换言之，我们的外表是习得的——而未与生俱来的。

　　婴儿的面部特征通常会受外界影响。根据伯德威斯泰尔的理论，婴儿通过观察周围的人——家人和朋友——学习眉头如何动作。这有助于解释，为什么在美国某些地方的人看上去那么相似。

　　新英格兰地区或者南部地区的人们面部特征有某些无法用遗传学解释的相似之处。完全一致的口型并非先天所致，而系后天习得。事实上，口部的最终定型要到新齿全部长出后才能完成。对许多人而言，这一过程一直到童年时期才结束。夫妻共同生活久了，经常看上去有些相像。我们从周围人那里习得了自己的相貌。

　　这也许可能解释，为什么在同一个国家内，有些地方的人会比其他地方的人微笑得更多。以美国为例，南方人微笑得最多，新西兰人（注：这里可以有误，估计应该是New England新英格兰）则少些，而纽约西区的人们被认为不友善，部分是因为麦迪逊大街上的人们比佐治亚州亚特兰大市桃树街上的人们微笑的少。在人口密集地区生活的人们，在公众场合相互微笑致意，要少于在小城镇里生活的人们。