Turns out, casual sex and hookups are not just about meaningless physical activity, but a source of intimacy. As part of the study, researchers sent a voluntary online questionnaire to several hundred college students and asked about their affectionate and intimate activities during sexual encounters in the contexts of both romantic relationships and casual sex.

The study found that partners were more likely to engage in affectionate and intimate activities in relationship sex than in casual sex-- but the rate of these acts in casual sex was much higher than hypothesised. The results of the research were published in the Journal of Relationships Research.