Men appear to devote more visual attention to the chest region of other men than women do, according to new research in Evolutionary Psychological Science. The study sheds new light on how shoulder-to-hip ratio influences perceptions of attractiveness.

“Men and women have sexually dimorphic physical characteristic and both men and women rate female faces bearing feminine features, such as full lips and small chin, more attractive than female faces with masculine traits,” said Farid Pazhoohi, a psychologist based at the University of British Columbia and the corresponding author of the new study.

“Similarly, individuals prefer female-typical body features such as low waist to hip ratios (small waist and broad hips) in women compared to masculine features (high waist to hip ratios). One male-typical sexually dimorphic trait is broad chests (larger upper body size) and is associated with being more successful with securing status and resources.”

“If having a larger upper body is a male-typical attribute, then women with smaller upper bodies should be considered more feminine and therefore more attractive. Similar to men, women’s body characteristics such as their upper body size show variations,” Pazhoohi told PsyPost.

“As the variations in women upper body have never been investigated, we aimed to test the effect of both men and women upper body size on their perceived attractiveness and gazing behavior in both men and women.”

For their study, the researchers tracked the eye movements of 82 heterosexual undergraduate students as they viewed and rated the attractiveness of three male and three female 3D models, which varied in their shoulder-to-hip ratio.

They found significant differences in how men and women judged the attractiveness of the male and female models.

“Our study showed that men rate men with larger upper body sizes more attractive and rate women with smaller shoulders (smaller upper body) more attractive, while women preferred an intermediate size of shoulders for both men and women,” Pazhoohi told PsyPost.

The researchers also found that men dwelled longer on the chest region of male 3D models with higher shoulder-to-hip ratios, while women showed no differences in visual attention to chests of the male models.

“Gazing results showed that only men attend to variations in men upper bodies. In sum, men are more concerned with men’s upper bodies, suggesting they desire more masculine body forms for their mating success as well as in making the assessment of other men’s formidability,” Pazhoohi explained.

Like all research, the study is not without limitations.

“Our findings regarding the female upper body size and also men preference for other men upper body size using eye-tracking are the first and certainly need to be replicated using different samples, ethnicities, stimuli, etc,” Pazhoohi said.

The study, “Sex Differences for Preferences of Shoulder to Hip Ratio in Men and Women: an Eye Tracking Study“, was authored by Farid Pazhoohi, Ray Garza, James F. Doyle, Antonio F. Macedo, and Joana Arantes.