達文西的畫作《蒙娜麗莎》能成為經典，很大程度是因為其捉不到的微笑，大家無論從那個角度去觀看，都會見到主角對自己微笑，但多年來都無人能拆解其箇中原因。

The study reveals how La Bella Principessa (right), painted by da Vinci before the Mona Lisa (left) in the late 15th Century, uses a clever trick to lure in the viewer. By expertly blending colours to exploit our peripheral vision, the shape of the subject's mouth appears to change according to view point, researchers found

但最近英國有研究指出，透過達文西的另一畫作《美麗公主》（La Bella Principessa），便可拆解出捉不到的微笑的奧秘。
若細心觀察《美麗公主》，大家會發現當你直視公主時，她的嘴角會微微朝下，但當望向畫的其他地方時，卻會在眼尾感覺到她在笑，嘴角是微微朝上。

《蒙娜麗莎》其實是運用了同樣原理，達文西巧妙地利用顏色，將觀眾對畫的外圍視覺減弱，焦點放在嘴上，令畫中的嘴隨觀眾的焦點改變。

When viewed directly, the slant of the mouth in the Mona Lisa (pictured) is distinctly downwards.  But as the eye moves elsewhere to examine other features, the mouth appears to take an upward turn, creating a smile that can only be seen indirectly

雪菲爾哈倫大學（Sheffield Hallam University ）以及新特蘭大學（Sunderland University）的專家表示這個方法叫暈塗法（Sfumato），很多畫家早曉這個技巧，但只有達文西運用得如此出神入化。專家再利用實驗解釋這個方法，他們安排實驗參加者，從遠處和近距離觀看兩幅畫，多數人都認為遠看的她們笑得較開心；其後研究員再將畫中主角的嘴或眼遮住，發現他們只是單憑畫中主角的嘴去判斷她們究竟是在笑，還是有其他表情。

 

The researchers asked volunteers to view digitally manipulated versions of three paintings - da Vinci's La Bella Principessa (top), Mona Lisa (middle) and Portrait of a Girl by Piero del Pollaiuolo (bottom). They changed the level of blur in the paintings to examine whether this changed the impression of a smile, as shown above

 

The researchers used masks on La Bella Principessa to examine whether it was just the mouth or the eyes as well that were involved in the illusion of her smile (as shown above). Their results suggest it is just the mouth that appears to be involved, despite claims by some that da Vinci made his paintings 'smile through their eyes'

 

 

來源：Daily Mail 英國《每日郵報》