New research explores the biopsychology of common sexual behaviors

Recent research provides new insight into the functions of common sexual behaviors, revealing how they contribute not just to physical pleasure but also to emotional bonding. A trio of studies, two published in the WebLog Journal of Reproductive Medicine and one in the International Journal of Clinical Research and Reports, examines the physiological and psychological dimensions of why men hold their partners’ legs and stimulate their breasts, what men gain from these acts, and how women experience them.

Researchers pursued these lines of inquiry because many frequently practiced sexual behaviors remain scientifically underexplored. While practices like a man holding a woman’s legs or performing oral breast stimulation are common, the specific reasons for their prevalence and their effects on both partners were not fully understood from an integrated perspective. The scientific motivation was to create a more comprehensive picture that combines biology, psychology, and social factors to explain what happens during these intimate moments.

“Human sexual behavior is often discussed socially, but many aspects of it lack meaningful scientific exploration,” said study author Rehan Haider of the University of Karachi. “We noticed a gap connecting physiological responses, evolutionary psychology, and relationship intimacy to why certain tactile behaviors are preferred during intercourse. Our goal was to examine these mechanisms in a respectful, evidence-based manner rather than rely on anecdote or cultural assumptions.”

The first study took a broad, mixed-methods approach to understand why men often hold women’s legs and engage in breast stimulation during intercourse. The researchers combined a review of existing literature with observational studies and self-reported surveys from adult heterosexual couples aged 18 to 50. This allowed them to assemble a model that connected male behaviors with female responses and relational outcomes.

The research team reported that 68 percent of couples practiced leg holding during intercourse. This position was found to facilitate deeper vaginal penetration and improve the alignment of the bodies, which in turn enhanced stimulation of sensitive areas like the clitoris and G-spot. Women in the study correlated this act with higher levels of sexual satisfaction.

The research also affirmed the significance of breast stimulation, noting that manual stimulation occurred in 60 percent of encounters and oral stimulation in 54 percent. This contact activates sensory pathways in the nipple-areolar complex, promoting the release of the hormones oxytocin and prolactin, which are associated with increased sexual arousal and emotional bonding. From a psychological standpoint, these behaviors appeared to reinforce feelings of intimacy, trust, and connection between partners.

“We were surprised by the consistency of emotional feedback among participants, particularly how strongly feelings of closeness and security were linked to these behaviors,” Haider told PsyPost. “It suggests an underestimated psychological component beyond pure physical stimulation.”

“The core message is that sexual touch preferences are not random—many are supported by biological reward pathways, emotional bonding hormones, and evolutionary reproductive strategies. Leg-holding and breast stimulation, for example, can enhance feelings of safety, intimacy, and arousal for both partners. Healthy communication and consent around such behaviors strengthen relational satisfaction.”

A second, complementary study focused specifically on the male experience of performing oral stimulation on a partner’s nipples. The goal was to understand the pleasure and psychological satisfaction men themselves derive from this act. To do this, researchers conducted a cross-sectional survey, recruiting 500 heterosexual men between the ages of 18 and 55. Participants completed a structured and anonymous questionnaire designed to measure the frequency of the behavior, their self-rated level of arousal from it, and its association with feelings of intimacy and overall sexual satisfaction.

The analysis of this survey data revealed a strong positive association between the frequency of performing nipple stimulation and a man’s own sense of sexual fulfillment and relational closeness. The results indicated that men do not engage in this behavior solely for their partner’s benefit. They reported finding the act to be both highly erotic and emotionally gratifying. The researchers propose that the behavior serves a dual function for men, simultaneously enhancing their personal arousal while reinforcing the psychological bond with their partner, likely through mechanisms linked to the hormone oxytocin, which plays a role in social affiliation and trust.

The third study shifted the focus to the female perspective, examining women’s physical and psychological responses to breast and nipple stimulation during penetrative intercourse. This investigation used a clinical and observational design, collecting data from 120 sexually active women aged 21 to 50. The methodology involved structured interviews, clinical feedback from counseling sessions, and the use of validated questionnaires, including the well-established Female Sexual Function Index (`FSFI`), a self-report tool used to assess key dimensions of female sexual function.

This research confirmed that stimulation of the breasts and nipples consistently contributed to a more positive sexual experience for women. Women with higher reported nipple sensitivity showed significantly better scores across the FSFI domains of arousal, orgasm, and satisfaction. Physically, this type of stimulation was associated with enhanced vaginal lubrication and clitoral responsiveness during intercourse.

Psychologically, the researchers found a connection between a woman’s perception of her breasts and her emotional experience. Women who described their breasts as “zones of intimacy” or “trust-enhancing touchpoints” reported a greater sense of emotional connection and reduced anxiety during sex. However, the study also identified that 23 percent of participants experienced discomfort during breast stimulation.

“This research does not imply that these behaviors are necessary or universally preferred,” Haider noted. “It’s also not about objectification. Rather, it focuses on how touch patterns can reinforce mutual trust, pleasure, and bonding when consensual and respectful. Not everyone will experience the same responses, and preferences vary widely. The study highlights trends—not prescriptions—and should be interpreted as an invitation for communication rather than a standard everyone must follow.”

While these studies offer a more detailed understanding of sexual behavior, the researchers acknowledge certain limitations. All three studies relied heavily on self-reported data, which can be influenced by memory recall and social desirability biases. The research was also primarily cross-sectional, capturing a snapshot in time, which can identify associations but cannot establish cause-and-effect relationships. For instance, it is unclear if frequent breast stimulation leads to higher intimacy or if more intimate couples simply engage in the behavior more often.

For future research, scientists suggest incorporating longitudinal designs that follow couples over an extended period to better understand the development of these behavioral patterns and their long-term effects on relationship satisfaction. There is also a need for more cross-cultural comparisons, as sexual scripts and preferences can vary significantly across different societies.

“Future work will explore female perspectives more deeply, neuroendocrine changes during different types of touch, and how cultural factors shape sexual comfort and preference,” Haider said. We’d like to compare findings across age groups and relationship durations as well. Sexual well-being is an important aspect of overall health, but it is rarely discussed scientifically. By approaching these topics with sensitivity and rigor, we hope to normalize evidence-based conversation and encourage couples to communicate openly.”

The studies, “Physiological Basis of Male Preference for Holding Women’s Legs and Breast Stimulation during Intercourse,” “Nipple Sucking and Male Sexual Response: Perceived Pleasure and Psychological Satisfaction,” and “Women’s Physical and Psychological Responses during Penetrative Sexual Intercourse: The Role of Breast and Nipple Sensitivity” were authored by Rehan Haider, Geetha Kumari Das, and Zameer Ahmed.