Evidence in humans suggests that men are especially competitive with other men over resources and, if successful, are valued as attractive mating prospects by women. Previous studies also show that men experience an increase in testosterone following a win and a decrease in testosterone following a loss. If an increase in testosterone following a victory is an evolved physiological response aimed at readying a man for an increase in mating opportunities, then experimentally manipulating competitive outcomes should differentially affect men’s sex-drive. One-hundred thirteen men were randomly assigned to experience a win, a loss, or no competitive feedback. Participants’ sex-drive was gauged by their responses to photographs of women of differential attractiveness. Results showed that only single men exhibited a higher sex-drive in the winning condition, followed by the control and losing conditions, respectively. Limitations and practical applications to decreasing instances of rape and sexual coercion are discussed. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection