The role of self-face on face recognition

Facial recognition provides information about biological and social characteristics such as gender, species, age, familiarity and emotional state. Facial morphometry is the most important component of an individual's facial identity and facial width to height ratio (fWHR) is the most important facial morphometric feature. In addition to providing quantitative information on facial morphology, fWHR has been shown in many studies to affect face perception through perceived social traits. The other-race effect (ORE), also known as the cross-race effect, involves recognizing and remembering faces of own race more quickly and successfully. In contrast, people show a decreased performance in recognizing and remembering faces of other races. The aim of the first study was to show how the level of fWHR for perceived faces and the participant's own face is a variable that affects face recognition performance, and how this effect varies for face stimuli of other races. On the other hand, humans process their own faces in a shorter time than other faces. Specific ERP potentials such as N170, N250, and P300 are observed for this mechanism. In this study, we will investigate how the "self-other classification mechanism" is affected when an individual's own face morphology is gradually transformed to the other face (0% = self, 25%, 50%, 75%, 100% = other) by creating composite faces. In addition to the behavioral measurement, the P100, N170, N250, N400, and P300 ERP components, which are related to the face recognition mechanism measured by EEG, will be measured to reveal how neural connections are affected by the gradual change of face morphology. As a result of the first study, it was found that the face recognition performance differed according to race and fWHR levels and that these variables interacted with each other. In the participants' own racial group, faces with average (Medium-Low, Medium-High) fWHR levels were recognized most accurately by the participants, while in the other racial group, faces belonging to the extreme fWHR groups (Low-High) were recognized most accurately by the participants. In addition, participants' fWHR levels were found to be correlated with their performance in recognizing perceived faces' fWHR levels. As a result, we may be using the average face space for faces with which we have experience, whereas for faces of other races, we may be evaluating them on distinctive features because we are not familiar with them and they do not have any affinity with us. In the second study, differences were found between composite face levels in N170 and P300 ERP components. In the analyses conducted on the N170 components, when the main effect of composite was analyzed, the highest N170 amplitude appeared in the "100% = other" condition, while the lowest N170 wave amplitude was shown in the "0% = own" condition. It was also observed that the wave amplitude gradually decreased from the 100% composite condition to the 0% composite condition. In the P300 component, participants showed a much higher P300 potential in the own face condition compared to the other conditions. In conclusion, the face-specific N170 component was linearly affected by the gradual morphometric change of the face.