A new psychology study suggests lip size can subtly shape how attractive a face is perceived, and that preferences can differ depending on the viewer’s gender. The research also indicates that recent visual exposure can shift what people see as appealing.
The work was led by Professor David Alais at the University of Sydney and used digitally altered images of faces that varied only in lip size. Participants were asked to rate attractiveness, allowing researchers to isolate lip size as a single factor.
Gender differences in lip preference
Across participants overall, ratings tended to favor thinner lips on male-presenting faces and fuller lips on female-presenting faces. When broken down by gender, women showed a stronger preference for fuller lips on female faces, while men more often preferred female faces with unaltered, natural-looking lip size.
The authors argue the pattern points to observer-dependent standards, meaning judgments are shaped not just by the face being viewed but also by who is doing the viewing. The findings were published in Proceedings of the Royal Society B.
How fast exposure can shift taste
The experiments also found an adaptation effect, where brief exposure to plumper or thinner lips changed what participants rated as attractive immediately afterward. After seeing fuller lips, people were more likely to rate fuller lips as attractive in subsequent faces, with a similar shift after exposure to thinner lips.
Notably, the effect appeared even when participants adapted to lips presented without the full face context, suggesting the brain may encode lip size as a distinct feature. Researchers say this kind of rapid recalibration has been observed in other areas of visual preference.
Implications for cosmetic trends and body image
With lip augmentation widely promoted through celebrity culture and social media, the study raises questions about how repeated exposure to enhanced features may reset perceived norms. Alais warned that this could contribute to a slide toward ever-plumper ideals, sometimes described as lip dysmorphia.
“Our research highlights the subjective nature of beauty and the powerful influence of social and cultural factors,” Alais said. The team says more research is needed to understand whether these short-term shifts accumulate into long-term changes in body image and aesthetic expectations.
In the study, 32 students, split evenly between women and men, rated 168 manipulated faces spanning seven lip sizes from thinner to fuller than a defined norm. Each image was shown briefly, designed to capture quick, instinctive judgments rather than slow deliberation.
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