The Effect Of Facial Parts And Perceptual Experience On The Fat Face Illusion

Fat face illusion is a visual illusion in face perception.Specifically,when two identical upright face pictures are aligned vertically,the bottom face looks slightly fatter than the top face.This illusion was first discovered and reported by Sun Yuhao et al.(2012).Previous studies have shown that the perception of the internal parts and the external parts(outside the face contour,the meaningful hair and ears,etc.)of a face have an important effect on the fat face illusion.But there are no researches to report that more finely analyzed(for example,with an insignificant,simple face contour as a baseline,systematically increasing the internal or external components of the face and examining under what conditions there will be a fat face illusion)or the expertise of face perception(With the increase in perceptual experience caused by the face of cognitive processing of fine)may have an effect on the fat face illusion.The purpose of this paper is to explore the above two issues,by systematically manipulating the inside and outside parts of the face and the facial perceptual experience of the subjects.The study one uses the experimental task of Sun Yuhao et al.(2012)(which allows the subjects to judge the relative fatness of two identical upright faces that are vertically aligned),examining the effect of the changes in the internal and external parts of the facial contour(meaningless closed contour)on the fat face illusion with two experiments.Experiment 1 was used to examine the subjects' perception of the facial fatness under the three conditions " blank"(no internal parts),"meaningless geometric figure " and "cartoon parts",using the internal parts of the facial contour as the independent variables.The results show that when the internal parts of the facial contour are "blank" or " meaningless geometric figure ",the subjects produced the fat face illusion.When the internal part of the facial contour is the cartoon part,the subjects produced the fat face illusion.Experiment 2 examined the subjects' perception of the facial fatness under the three conditions "blank"(no external parts),"ear","ear and hair",using the external parts of the facial contour as the independent variables.It was found that the subjects did not produce the fat face illusion when the external part of the facial contour was "blank"(no part).When the external part was "ear" or "ear and hair",the subjects had the fat face illusion.In summary,the results of the study show that the meaningless closed contour itself can not induce the fat face illusion,the similarity of the internal and external parts of the facial contours(meaningless closed contour)with the internal and the external features of the face,is an effective clue to induce the fat face illusion.Further,it suggests that the prerequisite of the fat face illusion is that the subjects perceive the current visual stimulation as a face,and the appearance of the fat face illusion depends on the topdown,concept-driven perceptual processing.The study two explores the effect of face perceptual experience on the fat face illusion.In experiment 3,the fat face illusion of adults induced by Asian adult faces(own age faces,subjects had more perceptual experience with such faces)and Asian children faces(other age faces,subjects had less perceptual experience with such faces)were examined.The results showed that there was a significant difference in the fat face illusion of Asian adult faces and Asian children faces: the intensity of the fat face illusion induced by other age faces(ie,children faces)was significantly weaker than that induced by own age faces(ie,adult faces),the age of face pictures has an effect on the strength of the fat face illusion.Experiment 4 examines the fat face illusion induced by Asian adult faces(own race faces,subjects had more perceptual experience with such faces)and Caucasian adult faces(other race faces,subjects had less perceptual experience with such faces).The results showed that there was a significant difference in the fat face illusion of Asian adult faces and Caucasian adult faces: the intensity of the fat face illusion induced by other race faces(ie,Caucasian adult faces)was significantly weaker than that induced by own race faces(Asian adult faces),the race of face pictures has an effect on the strength of the fat face illusion.In summary,the results of the study two show that persons' perceptual experiences of the faces have an effect on the strength of the fat face illusion.The results of the study one and study two suggest that:(1)the appearance of the fat face illusion depends on the top-down perceptual processing;(2)the perceptual experiences of faces that people contact with have an effect on the strength of the fat face illusion.