Delay and probability discounting as determinants of sexual risk behavior: the effects of delay, uncertainty, and partner's characteristics

The value of safe sex may be discounted based on contextual factors associated with an opportunity for sex. College students (n = 75) in a within-subjects study selected hypothetical sexual partners from a set of pictures and classified them based on attractiveness and estimated chance of having an STI. In the sexual delay discounting (SDD) task, participants rated their likelihood (0 – 100%) of waiting for some period of time (e.g., 3 hours) to have protected sex with their selected partners, when they could have immediate sex without protection. In the sexual probability discounting (SPD) task, participants rated their likelihood of having protected sex if the opportunity was uncertain (e.g., 50%), when they could have unprotected sex for sure (100%). All participants included in the final analyses were aware of and had a positive attitude towards protection against STIs as they indicated preference for immediate (or certain) protected sex. Results show that participants’ willingness to have safe sex systematically decreased as the delay to and odds against having safe sex increased. However, these discounting patterns were observed only in some partner conditions but not others, showing that preference for delayed (or uncertain) safe sex was altered by perceived attractiveness and STI risk of sexual partners. Moreover, the hyperbolic discounting model provided good to acceptable fit to the delay and probability discounting data in most-wanted and least-STI conditions. Gender differences in devaluation of safe sex were also found.