A study of sexual behavior and appearance

Background

How attractive one's sexual partner is compared to how attractive one sees oneself may influence sexual health behavior such as condom use. Prior qualitative work has suggested that sexual partners that one perceives to have a surplus of sexual capital relative to one's own may influence the sexual behaviors one is willing to engage in. This study seeks to investigate this experimentally. Using male faces from the Chicago Face Database that have been rated attractive or unattractive, we will see whether people who have sex with men shown an attractive versus unattractive demonstrated differences in their intentions to engage in condomless sex, and the perceived social pressure they experience to agree to condomless sex.

Research Questions / Hypotheses

We hypothesized that participants who see an attractive face will report greater intentions to engage in condomless sex, and greater social pressure to engage in condomless sex compared to participants who see an unattractive face. We also hypothesized that these effects will be moderated by participants' self-rated sexual desirability. For example, we expected that participants who see themselves as more sexually undesirable and who see an attractive face will report greater intentions to agree to condomless sex. In contrast, participants who are more sexually desirable and who see an attractive face will report fewer intentions to agree to condomless sex. For participants who see an unattractive face, we anticipate that participants who self-report being more sexually desirable will show lower intentions to agree to condomless sex than participants who self-report as undesirable, but that the effect will be attenuated.

Participants

We had a total sample size of 593. 18 participants were excluded for not completing the consent form, 63 for not completing the experimental manipulation, and 71 for failing both of our two attention checks. We had a final sample size of 441. Of these participants, 226 (51.25%) were assigned to condition 1 and saw an unattractive face (see 'Methods') and 216 (48.75%) were assigned to condition 2 and saw an attractive face.

Methods

We used face drawn from the Chicago Face Database and it's expansion stimuli. These faces were previously rated on attractiveness, so we used those faces that were rated one standard deviation below the mean on attractiveness ('unattractive' faces) and those rather one standard deviation above the mean on attractiveness ('attractive' faces). Participants were randomized to either see an unattractive or attractive face and then randomized to see one out of 65 (for attractive faces) or 67 faces (for unattractive faces) possible stimuli. Participants were shown the facial stimuli using a vignette. The vignette established that the participant met the person depicted (pseudonymously called 'Alex') on a dating app before going on a date with him. The vignette then described the participant going home with Alex to have sex. Alex then asked to have condomless sex, where the participant was asked how likely they were to agree, and the extent to which they felt social pressure to agree, to having sex will Alex.

Results

We used Bayesian statistics to analyze our data in the software Stan using R and R-Studio. This approach to statistics differs slightly from frequentist statistics taught in the undergraduate program in that our results represented the distribution of all the possible values of the relationships between our independent and dependent variables. We summarize each of our findings using the 'posterior mean' of these distributions and a 97% credible interval. This can be interpreted, respectively, as 'the most likely' strength and direction of the relationship in question, and the range of the likeliest values the relationship could take. For simplicity, if the 97% CI does not include zero, the relationship can be thought of as meaningfully different from zero (i.e., 'significant'). We found that participants who saw a face rated attractive had greater intentions of agreeing to have sex with Alex, β = .29 (97% CI [.09, .50]), partially supporting our hypothesis.

Contrary to our expectations, self-rated sexual desirability to not influence the intention of agreeing to have sex with Alex, β = .03 (97% CI [-.12, .18]), and we found no interaction between self-rated desirability and experimental condition, b = .00 (97% CI [-.01, .02]). This suggests that one's partner's sexual attractiveness influences how likely one is to agree to have sex and that this occurs regardless of how sexually attractive one sees oneself as. We found that participants who say themselves as more sexually desirable experienced less social pressure to have condomless sex with Alex, β = -.16 (97% CI [-.30, -.01]), partially supporting our hypothesis. Note, however, that the upper bound of the CI is very near to 0 at -.01, suggesting that the relationship may not be very meaningful, and suggesting we need more data to reach a more confident estimate of the relationship. We found that experimental condition did not appear to predict social pressure, -.17 (97% CI [-.37, .04]), suggesting that others' sexual attractiveness does not influence how much social pressure participants felt to agree to condomless sex. Two things are notable about this finding. First, as the upper bound of the CI is close to 0, we can't necessarily conclude there is no relationship. Rather, as above, we may need more data to come to a more confident estimate on whether and to what extent a relationship exists. Second, the posterior mean is negative, suggesting that participants who saw an attractive face experienced less social pressure to agree to condomless sex, which contradicts our hypothesis. Finally, we did not find a significant interaction effect, b = .00 (97% CI [-.01, .02]).

Implications

Our findings have some sexual and public health implications. First, people may make riskier sexual health decisions when their partner is seen as attractive. For people assigned female at birth, this may increase the chances of sexually transmitted infections (STIs), unwanted pregnancies, and bloodborne diseases such as HIV and hepatitis. For men and nonbinary people who have sex with gay and bisexual men, this may increase the chances of STIs and bloodborne diseases. Second, and more theoretically, sexually attractive men may be able to leverage their desirability to 'coerce' others into otherwise unwanted and risky sex. Greater sexual health and consent education may stymie this effect, mitigating the risks that condomless sex poses to individuals' sexual and physical health. Lastly, self-rated sexual desirability decreases the amount of social pressure participants felt to agree to condomless sex. While we will need to explore the implications of this in a future project, this finding may suggest that interventions aimed at improving one's view of oneself as a sexual being may improve their adherence to safe sex practices. Participants who completed this study were also asked to respond to whether they would like a copy of the published manuscript. We hope to have the data published in early-to-mid 2025. Please contact Wesley Grey (wgrey@student.unimelb.edu.au) if you would like to receive a copy of the publication once available. We also hope that Wesley will present the findings from this project at conferences in 2025, such as the Society for the Scientific Study of Sexuality and Society of Australasian Social Psychologists' annual conferences.