Sexual desire evolved to serve as a powerful motivational force that brings potential romantic partners together initially and thereby helps to facilitate sexual intercourse and pregnancy. As such, sexual acts may be devoid of affectional bonding, as in the case of one night-stands. And yet, sexual desire may play a major role not only in attracting potential partners to each other, but also in encouraging the formation of an attachment between them.

Nevertheless, thus far it has been unclear whether desire motivates merely reproductive acts, with attachment between partners developing independently, or whether desire directly contributes to the building of an emotional bond between newly acquainted partners. Indeed, although sexual urges and emotional attachments are not necessarily connected with each other, evolutionary and social processes may have rendered humans particularly likely to become romantically attached to partners to whom they are sexually attracted.

Research published recently in the Journal of Social and Personal Relationships has provided support for the latter option. In four studies, my colleagues and I demonstrate that sexual desire elicits behaviors that can facilitate emotional bonding during face-to-face encounters with a new opposite-sex acquaintance.

In Study 1, we examined whether desire for a new acquaintance would be associated with enactment of non-verbal immediacy behaviors that indicate contact readiness (e.g., synchronization, close physical proximity, frequent eye contact). To do so, participants took part in a lip-sync performance in which they and an attractive opposite-sex confederate mimed together to pre-recorded music (without actually singing) while being videotaped. Participants then rated their desire for the confederate. Judges rated the extent to which participants enacted immediacy behaviors toward the confederates and were behaviorally synchronized with them. We found that participant’s desire for the confederate was associated with coded immediacy behaviors toward the confederate as well as with synchronization as perceived by participants, confederates, and raters.

In Study 2, we sought to replicate the findings of Study 1 with a different methodology that requires more intimate coordination (slow-dance rather than lip-sync performance) and is thus more relevant to romantic contexts. We also wished to extend Study 1 by adding a measure of interest in future interactions with potential partners. For this purpose, participants slow-danced with an opposite-sex confederate and then rated their sexual desire for the confederate, the extent to which they were synchronized with each other, and their interest in seeing the confederate again. The results showed that participant’s desire for the confederates was associated with being synchronized with them, which in turn, predicted greater interest in dating them.

Studies 3 and 4 were designed to establish a causal connection between activation of the sexual system and non-sexual behaviors (provision of responsiveness and help, respectively) that are not only strategically employed to initiate relationships with potential partners but also play a key role in supporting long-term bonding3.

In Study 3, participants were subliminally exposed to sexual stimuli (versus neutral stimuli). Specifically, participants were asked to indicate their food, clothing, and location preferences for a date by choosing one of two options from each of seven categories (e.g., color of clothes: black or blue; location: bar or restaurant). Before each pair of options, participants were exposed to either a sexual (an attractive naked, reclining man shown from the groin up for female participants; an attractive, naked, kneeling woman photographed from behind for male participants) or a neutral prime, which was presented subliminally.

Then, participants discussed several interpersonal dilemmas (e.g., “Are you for or against playing ‘hard to get’ at the start of a relationship?”) with an opposite-sex participant whom they did not know while being videotaped. Judges rated the extent to which participants engaged in behaviors that conveyed responsiveness and caring to the confederate during the interactions. The findings revealed that participants were more responsive to the other participant in the sexual priming condition than in the control condition.

In Study 4, we sought to activate the sexual system in a more ecologically valid manner, investigating how sexual stimuli in real-life settings (watching videos) affect engagement in other approach behavior (i.e., helping behaviors) that may facilitate relationship initiation more actively than provision of responsiveness. In particular, participants watched either an erotic (but not pornographic) video or a neutral video. After watching the video, participants were led to believe that in the next 5 minutes they and another participant would complete a questionnaire assessing their verbal reasoning. The experimenter then introduced an attractive opposite-sex confederate to the participants, seated them next to each other, told both that they were allowed to speak with each other while completing the questionnaire, and left the room.

When the confederate ostensibly got to the third question, he or she turned to the participants and asked their help in solving that question, uttering, “I’m stuck with this question. Could you please help me in solving it?” Participants’ helping behaviors toward the confederate were recorded, using the following measures: (a) the time elapsed until participants started providing help to the confederate; (b) the actual time spent helping solving the needed question; both were measured using a stopwatch hidden in the confederates’ pocket; and (c) the quality of the given help, as assessed by the confederate following this session. The findings indicated that participants were quicker to help as well as invested more time and effort in providing help to the confederate in the sexual priming condition than in the control condition.

Overall, our research demonstrates that even a nonconscious sexual stimulus can elicit verbal and non-verbal behaviors that not only convey contact readiness but also express caring about a partner’s well-being. By doing so, our research suggests that when two strangers meet, sexual desire experienced by one or both of them may initiate a cascade of behaviors that signal their interest in further interaction as well as their willingness to invest in a potential relationship. Such behaviors help set the stage for deepening the emotional connection between them. To be sure, whereas intense desire may attract new partners to each other, the behaviors it engenders are those that support long-term bonding.