The Adaptive Significance of Sexual Conditioning: Pavlovian Control of Sperm Release

Male quail received Pavlovian conditioning trials that consisted of placement in a distinctive experimental chamber (the conditioned stimulus) paired with the opportunity to copulate with a female (the unconditioned stimulus). For control subjects, exposures to the conditioned and unconditioned stimuli were unpaired. After four and six trials, each subject was placed in the experimental chamber with a probe stimulus that included some of the visual cues of a female's head and neck. Pavlovian conditioning increased how much time subjects spent near the probe stimulus. Conditioned subjects also released greater volumes of semen and greater numbers of spermatozoa than the control subjects. Significant differences were not obtained in serum testosterone levels or in other measures of sperm quality. These results demonstrate that sexual Pavlovian conditioning can affect reflexes involved in sperm release and thereby modulate reproductive fitness.