A real-life illusion of assimilation in the human face: eye size illusion caused by eyebrows and eye shadow

Abstract

Does an assimilative illusion like the Delboeuf illusion occur in the human face? We investigated factors that might influence the perceived size of the eyes in a realistic face. Experiment 1 manipulated the position of the eyebrows (high or low), the presence/absence of eye shadow, and the viewing distance (0.6 m or 5 m), then measured the perceived eye size using a psychophysical method. The results showed that low eyebrows (i.e., closer to the eyes) make the eyes appear larger, suggesting that the assimilation of eyes into the eyebrows is stronger when the eye-eyebrow distance is shorter. The results also demonstrated that the application of eye shadow also makes the eyes look larger. Moreover, the effect of eye shadow is more pronounced when viewed from a distance. In order to investigate the mechanism of the eye size illusion demonstrated in Experiment 1, Experiment 2 measured the magnitude of the Delboeuf illusion at a viewing distance of 0.6 m or 5 m, with or without gray gradation simulating the eye shadow that was used in Experiment 1. The experiment demonstrated that the Delboeuf illusion is modulated by viewing distance and gradation in the same way as the eye size illusion. These results suggest that the eye size illusion induced by the eyebrows and the Delboeuf illusion involve the same mechanism, and that eye shadow causes the assimilation of the eyes into itself and enhances assimilation between the eyes and the eyebrows.

Makeup changes the apparent size of facial features.

“…We predicted that the eyes and mouth would look larger with makeup. Indeed, the eyes were perceived as larger with makeup than without across all three studies, corroborating recent work by Morikawa et al (2015).…”

“…Despite the widely held belief that makeup makes the eyes and lips look larger, the idea has received almost no scientific evaluation. Recently, Morikawa and colleagues used psychophysical methods to test whether the eyes appear larger when wearing eyeshadow (Morikawa, Matsushita, Tomita, & Yamanami, 2015). They found that faces wearing eyeshadow appear to have larger eyes, and that the effect is moderated by the distance between the eyes and the eyebrows, as well as by the viewing distance from the face.…”

Differential effects of makeup on perceived age

“…Aspects of facial contrast are sexually dimorphic, being greater in female than male faces (Jones et al ., ; Russell, ; Russell, Kramer, & Jones, ), while other aspects decline with age and are used as cues for perceiving age and health from the face (Porcheron, Mauger, & Russell, ; Porcheron et al ., ; Russell et al ., , ). Theorists have proposed that facial feature size mediates the effect of makeup on attractiveness (Bruce & Young, ; Morris, , ; Perrett, ; Zebrowitz, ), and recent work has shown that makeup does indeed make the eyes and eyebrows appear larger (Morikawa, Matsushita, Tomita, & Yamanami, ). Makeup can also make the nose appear smaller, through the use of contouring, but typically does not make the lips appear any larger (Jones, Porcheron, & Russell, in press).…”

Chen’s Double Eyelid Fold Ratio

“…Third, the eye size illusion is also induced by the distance between the eyebrow and eye and may involve a different type of assimilation illusion. 24 The shortened distance between the eyebrow and eye is reported to increase the illusion of a larger eye. 25 Hence, the visually perceived dimension and aesthetics of the eye are further influenced by the relative proportions of the eyebrow–eye anatomical unit.…”