Unveiling the "Less is More" paradox: How experience and cognitive filling drive attractiveness in occluded faces.

The "Less is More" phenomenon, the intriguing elevation of facial attractiveness under conditions of limited visual information (e.g., masked faces), has garnered significant attention since the COVID-19 pandemic. This study delves into the influence of experience on this phenomenon and its underlying cognitive mechanisms through three experiments. Experiment 1 examined attractiveness ratings of occluded, predicted and complete faces with four occlusion types before and after the pandemic onset. Experiment 2 investigated how participants mentally complete faces occluded by sunglasses by selecting from high-, low-attractiveness, and average eye representations. Experiment 3 explored the impact of familiarity. Participants first familiarized themselves with half of the faces, then rated the attractiveness of the occluded and predicted versions of all familiar and unfamiliar faces, and finally chose the original complete face from a set of foils (high-attractiveness, low-attractiveness, and average face) . Across all experiments, the inherent attractiveness of the complete faces was manipulated. Our findings reveal a clear effect of experience on the "Less is More" effect: it was amplified post-pandemic (Experiment 1), more pronounced for unfamiliar faces (Experiment 3), and consistently stronger for initially low-attractiveness faces. Selection patterns in Experiments 2 and 3, with average faces chosen most often for unfamiliar faces, support the Average/Typical Filling hypothesis. However, familiar faces elicited a preference for the original features, suggesting a memory-driven process. These results revealed a dynamic interplay between prior experience and visual constraints in shaping facial attractiveness perception.Statement of significance: The ubiquitous adoption of face masks during the COVID-19 pandemic, a global reality that suddenly obscured portions of the face, provided an unprecedented lens through which to examine the fundamental principles of facial attractiveness perception. The intriguing "Less is More" effect, where masked faces often appeared more appealing, directly inspired our investigation into how the human brain processes incomplete visual information and the role of experience in shaping these judgments. By systematically analyzing attractiveness ratings across diverse occlusion types before and after the pandemic and by exploring the cognitive "filling-in" mechanisms for both familiar and unfamiliar individuals, our work transcends a mere description of the "mask effect". Instead, it delves into the core processes underlying attractiveness evaluation when visual input is limited. Our findings reveal that the "Less is More" effect was amplified by increased real-world exposure to masked faces, and that our mental reconstructions of occluded faces diverge based on familiarity. Importantly, our results also identify specific occlusion types that most effectively enhance perceived attractiveness. This "use-inspired basic research," born from a tangible global event, not only illuminates the psychological impact of the pandemic but also yields fundamental insights into the adaptable nature of attractiveness perception under conditions of limited visual information, with potential relevance for understanding aesthetic preferences in various real-world contexts, including virtual interactions and artistic design.