Summary: New research shows that lip size has a noticeable effect on how people judge facial attractiveness, and those judgments vary by the observer’s gender and recent visual experience. Female participants tended to prefer fuller lips on female faces, while male participants generally preferred natural lip proportions. The study also found that recent exposure to altered lip sizes can change future attractiveness ratings, even when lips are seen in isolation. These findings suggest that trends such as lip augmentation can shift cultural beauty standards and may contribute to lip-focused body image concerns.
Researchers used digitally manipulated images to change lip size on faces that appeared male or female and asked participants to rate attractiveness. The results reveal both gender-specific preferences and a strong visual adaptation effect that can reshape what people find attractive after short-term exposure to altered lip sizes.
Key facts:
- Gendered judgments: Women in the study favored plumper lips on female faces, while men tended to prefer unaltered, natural lip sizes on female faces.
- Visual adaptation: Brief exposure to faces with plumper or thinner lips shifted subsequent attractiveness judgments toward the lip size seen during exposure.
- Independent encoding: Adaptation effects were observed even when participants viewed lips in isolation, indicating that lip size is processed as a distinct facial feature by the visual system.
Source: University of Sydney
Overview
A team led by Professor David Alais at the University of Sydney’s School of Psychology investigated how variations in lip size affect perceived facial attractiveness. The work examines the intersection of visual perception, social influences, and cosmetic trends, and suggests that the increasing popularity of lip-enhancing procedures could change collective tastes over time.
Participants viewed a large set of faces with lips digitally adjusted to be thinner or fuller than a defined norm and rated each image for attractiveness. The study measured immediate preferences and how exposure to altered lip sizes affected later judgments. Results demonstrate both an overall pattern and important differences when data are broken down by the gender of the observer and the gender appearance of the face.
The research is published in the Proceedings of the Royal Society B.
Main findings
- Overall pattern: Across all observers, male-appearing faces with slightly thinner lips and female-appearing faces with slightly fuller lips received the highest attractiveness ratings.
- Observer gender matters: Female observers showed a particularly strong preference for fuller lips on female faces. Male observers, by contrast, preferred female faces with natural, unaltered lip size. This indicates that judgments about attractiveness are influenced by the gender of the person making the judgment.
- Visual adaptation effect: Brief exposure to faces with exaggeratedly plump or thin lips biased later attractiveness ratings in the direction of the exposure. In other words, seeing fuller lips made participants more likely to rate fuller lips as attractive afterward, and the reverse was true for thinner lips.
- Lips considered independently: The adaptation effect persisted even when participants viewed lips in isolation rather than whole faces, implying that lip size is encoded separately from other facial features and can drive preference changes on its own.
Implications for body image
Professor Alais, an expert in visual perception and cognitive neuroscience, highlighted the potential real-world consequences of these findings. As cosmetic procedures such as lip fillers become more accessible and visible in media and social networks, they may recalibrate what people consider attractive.
The study suggests two important points: first, lip augmentation is likely to be most appealing to some women rather than men, and second, repeated exposure to enhanced lips can shift the perceived norm toward fuller lips. That shift could contribute to a form of “lip dysmorphia,” in which individuals feel dissatisfied with their natural lip size because their internal standard of attractiveness has been renormalized.
“These results emphasize the subjective nature of beauty and how social and cultural exposure can quickly alter visual preferences,” Professor Alais said. “Understanding these mechanisms is important as cosmetic interventions become increasingly common.”
Method and results in brief
Working with Associate Professor Jessica Taubert from the University of Queensland, Professor Alais recruited 32 student volunteers (16 female, 16 male). Participants viewed 168 images that varied across seven lip-size levels, from thinner to fuller than a baseline norm. Each image was displayed for 1.25 seconds, and observers rated relative attractiveness.
Overall, slightly fuller lips were rated more attractive for female-appearing faces and slightly thinner lips for male-appearing faces. When responses were examined by observer gender, women preferred fuller lips on female faces while men preferred natural lip sizes on female faces.
Next steps
Professor Alais noted that the results point to a complex interaction between cultural exposure and gendered preferences. He recommends further research to assess the long-term effects of cosmetic trends on body image and whether visual adaptation contributes to lasting body dysmorphic concerns.
About this beauty perception and psychology research news
Author: Marcus Strom
Source: University of Sydney
Contact: Marcus Strom – University of Sydney
Image: The image is credited to Neuroscience News
Original research: Open access. “Distortions of lip size bias perceived facial attractiveness” by David Alais et al., Proceedings of the Royal Society B Biological Sciences. DOI: 10.1098/rspb.2025.0202
Abstract
Distortions of lip size bias perceived facial attractiveness
Perceptions of facial attractiveness influence choices in social interaction, dating, hiring, and other decisions, but the visual mechanisms that determine attractiveness are not fully understood. While many models emphasize holistic face processing, people frequently attempt to alter specific features to increase attractiveness, such as through cosmetics or injectables. This study uses local feature manipulation—expanding or contracting lip size—to examine how such changes affect judgments of attractiveness for male- and female-appearing faces.
Results show that females prefer expanded lips when viewing female faces, while males prefer contracted lips when viewing male faces, indicating that distortions of lip size primarily influence attractiveness judgments for the observer’s own gender. Exposure to expanded or contracted lips also shifted peak attractiveness toward the adapted lip size. Because cosmetic procedures that increase lip size are common, these findings suggest that lip plumping will be more appealing to some women than men and that exposure to enhanced lips can renormalize attractiveness standards, potentially contributing to lip-focused body image concerns.