A composite face effect for vertically divided faces

The composite face effect (CFE) provides evidence for holistic face processing by demonstrating that when halves of different faces are aligned to resemble a single face, recognition of the component identities is disrupted. However, if the face halves are misaligned, the component identities become easier to recognise. While the horizontal CFE - wherein the top and bottom halves of the face are aligned - has been extensively studied, the existence of a vertical CFE - involving the combination of left-right face halves - remains unclear. This study investigated the vertical CFE using composite stimuli created by pairing familiar and unfamiliar faces. Participants made familiarity judgements for aligned and misaligned vertical and horizontal composites. Familiarity judgements were made more accurately and with faster response times with misaligned compared to aligned composites. The magnitude of the vertical CFE was comparable to the horizontal CFE and was unaffected by identity priming or which half of the face was attended. However, the size of the CFE was reduced when attention was not directed to a specific face half. These findings suggest that both the vertical and horizontal CFE reflect a common mechanism for integrating facial information across the visual field, underscoring holistic processing as a fundamental process in face recognition.