What Type of Facial Information Underlies Holistic Face Processing?

Holistic face processing is often referred to as the inability to selectively attend to part of faces without interference from irrelevant facial parts. While extensive research seeks for the origin of holistic face processing in perceiver-based properties (e.g., expertise), the present study aimed to pinpoint face-based visual information that may support this hallmark indicator of face processing. Specifically, we used the composite face task, a standard task of holistic processing, to investigate whether facial surface information (e.g., texture) or facial shape information underlies holistic face processing, since both sources of information have been shown to support face recognition. In Experiment 1, participants performed two composite face tasks, one for normal faces (i.e., shape + surface information) and one for shape-only faces (i.e., without facial surface information). We found that facial shape information alone is as sufficient to elicit holistic processing as normal faces, indicating that facial surface information is not necessary for holistic processing. In Experiment 2, we tested whether facial surface information alone is sufficient to observe holistic face processing. We chose to control facial shape information instead of removing it by having all test faces to share exactly the same facial shape, while exhibiting different facial surface information. Participants performed two composite face tasks, one for normal faces and one for same-shape faces. We found a composite face effect in normal faces but not in same-shape faces, indicating that holistic processing is mediated predominantly by facial shape rather than surface information. Together, these results indicate that facial shape, but not surface information, underlies holistic face processing