Decoding face identity: A reverse-correlation approach using deep learning

Face recognition is crucial for social interactions. Traditional approaches primarily rely on subjective judgment, utilizing a pre-selected set of facial features based on literature or intuition to identify critical facial features for face recognition. In this study, we adopted a reverse-correlation approach, aligning responses of a deep convolutional neural network (DCNN) with its internal representations to objectively identify facial features pivotal for face recognition. Specifically, we trained a DCNN, namely VGG-FD, to possess human-like capability in discriminating facial identities. A representational similarity analysis (RSA) was employed to characterize VGG-FD's performance metrics, which was subsequently reverse-correlated with its representations in layers capable of discriminating facial identities. Our analysis revealed a higher likelihood of face pairs being perceived as different identities when their representations significantly differed in areas such as the eyes, eyebrows, or central facial region, suggesting the significance of the eyes as facial parts and the central facial region as an integral of face configuration in face recognition. In summary, our study leveraged DCNNs to identify critical facial features for face discrimination in a hypothesis-neutral, data-driven manner, hereby advocating for the adoption of this new paradigm to explore critical facial features across various face recognition tasks.