Double-Eyelid Eye Size Illusion Brought by Eyeliner of Different Thicknesses and the Sense of Incongruity on the Illusion as an Effect
Eyeliner is one of the makeup methods that enhances the attractiveness of female by an optical illusion that makes eyes appear larger. Eyeliner has no fixed shape, and its thickness and length can be freely adjusted. In this study, we experimentally verified the relationship between thickness of eyeliner and the amount of the illusion. In addition, by examining the sense of incongruity of the eyeliner, we clarified the optimal thickness of eyeliner as makeup to make eyes appear larger. The results showed that the thicker eyeliner, the larger eyes were perceived to be. Furthermore, excessive thickness of eyeliner increased the sense of incongruity and reduced the illusion effect.