The Research Of The Relationship Between The Face Part Similarity And The Overall Similarity

The judgment of similarities is the base of cognitive activity, it is involved in many cognitive activity, such as memory, category, decision-making, problem-solving and inference. Previous researches related on similarity judgment assumed that the category standard in classification is clear. However, the mental activity is fuzzy; it proposed that the judgment of similarity is considered to be one kind of fuzzy judgments. Compare with the method of traditional evaluation, the multistage evaluation method was more practical, and it is frequently adopted to measure the similarity judgment. The present study used such method of multistage evaluation method, to investigate the weight conferred on the different parts of the human face.The observation on face is the most reliable way to recognize individuals. Even it is an unfamiliar face, we can get information about the individual such as age, sex, status and mood. Previous researches about similarity judgement pay less attention to the relationship of face part similarity and overall face similarity. Faces belong to natural category, and natural category has the characteristics of family resemblance. Furthermore, previous studies constructed the family resemblance structure in the follow way:each exemplar had one dimension that differed from the prototype; the dimensions which differed from the prototype were different. It is hardly to find the exemplar in the natural categories that have only two values in one dimension. In contrast, there are many values about the size of eyes and mouth, as well as the shape of the nose. Thus, we used the Morph deformation software to construct family resemblance and explored the relationship between the face part similarity and the overall face similarity.Study1investigated the relationship between the face part similarity and the overall face similarity. Three experiments were included. Experiment1investigated the similarity judgment of face part exemplar and the face part prototype, and explored the membership of the part exemplar to the part prototype; Experiment2investigated the similarity judgment of face part exemplar and the corresponding part in the prototype. Especially, we explored how the other parts in the prototype influenced the similarity judgment of target part by comparing the membership of part exemplar to the part prototype and the membership to the corresponding part in the face prototype;Experiment3investigated the similarity of face exemplar(which consisted of different parts whose membership to the prototype was different) and face prototype, and investigated the weight conferred on the different parts of the human face in the similarity judgment. In study2, we used the eye tracking methods by analyzing the eye movement data in the similarity judgment, to investigate how different parts influenced the face similarity judgment, and how the other parts influenced the target part in the similarity judgment. In experiment4, we analyzed the fixation to the part in the prototype when participants were asked to judge the similarity of the part and the corresponding part in the prototype, to investigate how the other parts influenced the similarity judgment of the target part; Experiment5investigated how different face parts worked in the face similarity judgment by analyzing the fixation to the part in the prototype when participants were asked to judge the similarity of the face exemplar and the face prototype.To summarize, the findings of the two studies are as follows:(1)The similarity of the part exemplar to the prototype could be measured by the membership degree, the relationship between the membership of the exemplar to the part prototype and the deformation percentage of the part is a cubic function, and the relationship between the membership of the exemplar to the corresponding part in the face prototype and the deformation percentage of the part is a cubic function as well;(2)The membership of the ear, face outline, and the eye exemplar to the corresponding part in the face prototype were lower than the membership which belonged to the part prototype, but the membership of the mouth exemplar to the face prototype was higher than the part prototype, it is more obvious in the middle and the late stage;(3)In the face-face similarity judgment, the weight of four different face parts varied to some extent:the highest was the face outline with0.550, which was significant higher than the other parts, then the mouth was in the middle (0.250), and ears and eyes were at the lowest(about0.100);(4)Compare with the "very dissimilar" condition, total fixation time is significantly longer when the judgement between the exemplar and the prototype was "very similar" or "similar".Following conclusions are made:(1)The relationship of the physical similarity and psychological similarity of the face part is a cubic function;(2)The other parts of the face influence the similarity judgment of the target part exemplars’membership to the corresponding part in the face prototype, other face parts in the face prototype decreased the membership of the ear, face outline, and the eye exemplar, but increased the membership of the mouth exemplar to the face prototype; it is more obvious in the middle and late stage;(3)Different parts of the face played different roles on the face similarity judgment. Compared with ears and eyes, the face outline and mouth were of more importance;(4)Compare with the "very dissimilar" condition, the process was more complicated when the judgement between the exemplar and the prototype was "very similar" or "similar".