Current research findings provide insight into how the shoulder-hip ratio influences the perception of attractiveness at a neural level. The study, published in the Sexual Behavior Archivesrevealed pronounced fluctuations in brain activity associated with men’s upper body size, but less pronounced differences in women’s ratings, highlighting the evolutionary importance of men’s upper body size in judging attractiveness.
Researchers conducted this study to examine how upper body size, particularly shoulder-to-hip ratio, affects the neurophysiological and behavioral responses associated with the perception and attractiveness of both male and female body figures. Men and women tend to find those with larger chests more attractive because they are associated with masculinity, a strong immune system, and other characteristics. However, there has been limited insight into how these relationships are reflected in brain activity.
“While there are studies on the neural correlates of facial attractiveness, in the current study we examined for the first time how upper body size modulates neurophysiological correlates relevant to perception and attractiveness,” said study author Farid Pazhoohi, lecturer in psychology the University of Plymouth University.
“In this study, we particularly examined the influence of the shoulder-hip ratio, the circumference of the shoulders in relation to the hips, on the attractiveness assessment of male and female body figures. Shoulder-to-hip ratio is a sexually dimorphic trait in humans and an indicator of male attractiveness for both men and women.”
The study involved 48 participants (28 females) aged between 18 and 37 years, recruited from the University of Minho. To collect data, participants completed questionnaires to collect sociodemographic information and performed two different tasks: an oddball task and an attractiveness judgment task.
In the oddball task, participants were presented with avatars with different shoulder-to-hip ratios and were instructed to press a key when they detected the presence of flowers on a T-shirt, representing a rare “oddball” event. In contrast, in the attractiveness judgment task, participants rated the attractiveness of avatars with different shoulder-to-hip ratios on a 7-point Likert scale.
The researchers used DAZ 3D Studio software to generate the avatars and created six variations for each gender by manipulating the shoulder-hip ratios to represent small, medium and large ratios. These shoulder-to-hip ratios were based on previously determined measurements for men.
Regardless of participant gender, there was a unanimous preference for avatars with a larger shoulder-to-hip ratio. In other words, both male and female participants rated both the male and female avatars with larger shoulder-to-hip ratios as more attractive compared to the avatars with smaller shoulder-to-hip ratios.
The researchers used EEG (electroencephalogram) analysis to delve deeper into the neurological mechanisms underlying attractiveness judgments. EEG is a non-invasive method of recording electrical activity in the brain and provides valuable insight into brain responses.
The study focused on so-called “temporal factors” (TFs) derived from the EEG data. These TFs represent specific patterns of electrical activity in the brain over time, allowing researchers to determine exactly when and how the brain responds to different stimuli.
In the oddball task, EEG analysis revealed that male avatars with larger shoulder-to-hip ratios elicited more pronounced negative neural responses in a specific temporal factor, namely TF5. This suggests that certain brain regions associated with processing visual information and possibly emotional responses showed more active negative responses when participants observed male avatars with larger shoulder-to-hip ratios.
In addition, the researchers used LORETA analysis, a special technique that helps identify the specific brain regions responsible for these electrical activities. They found higher activation in the right postcentral gyrus when participants were exposed to male avatars with large shoulder-hip ratios compared to those with medium shoulder-hip ratios (as identified in TF4). The postcentral gyrus is associated with processing sensory information from the body, suggesting that larger shoulder-to-hip ratios in male avatars may have triggered greater sensory processing in this region.
In the male avatar attractiveness judgment task, EEG analysis showed that small shoulder-hip ratios elicited more negative neural responses compared to medium shoulder-hip ratios, and this was evident at TF5. Similarly, LORETA analysis showed differences in brain activity with higher activation in the right cuneus when participants rated male avatars with small shoulder-hip ratios compared to medium shoulder-hip ratios (as identified in TF3). The cuneus is associated with processing visual information, suggesting that smaller shoulder-to-hip ratios may have led to increased visual processing in this brain region.
Interestingly, no significant differences in neural responses were observed in female avatars in either the oddball task or the attractiveness judgment task. This suggests that neural processing of attractiveness judgments may differ between male and female avatars. These results highlight the potential for gender-specific neural responses related to attractiveness judgments and add an additional layer of complexity to our understanding of how the brain perceives and evaluates physical characteristics such as shoulder-hip ratio.
“While the behavioral findings showed that both men and women found larger torso sizes more attractive than smaller ones in both male and female avatars, the EEG results suggested that brain activity associated with male torso size varied depending on specific proportions. “in early and late stages of processing,” Pazhoohi told PsyPost. “However, differences in neural activity associated with female upper body size were less pronounced.”
“In simpler terms, while differences in brain activity associated with upper body size of male avatars were evident both at the surface and deep in the brain, differences in upper body size of female avatars were only observed in deep brain activity and within a narrower time frame.” observed in men. This research, the first of its kind to examine brain activity in response to perception of upper body size, highlights the evolutionary significance of upper body size in men compared to women at the neural level.
“Our finding at the neural level confirms previous findings that men and women find men (but probably not women) with larger chests more attractive, as such a trait in men is associated with traits such as masculinity and a strong immune system and combativeness.” Terribility and the ability to access resources,” Pazhoohi explained.
The study, “Neural Correlations and Perceived Attractiveness of Male and Female Shoulder-to-Hip Ratio: An EEG Study,” was authored by Farid Pazhoohi, Joana Arantes, Alan Kingstone and Diego Pinal.