Orgasm men are capable of achieving them is supported by men who have reported having multiple, consecutive orgasms, particularly without ejaculation. Males who experience dry orgasms can often produce multiple orgasms, as the refractory period is reduced. An increased infusion of the hormone oxytocin during ejaculation is believed to be chiefly responsible for the refractory period, and the amount by which oxytocin is increased may affect the length of each refractory period. Another chemical which is considered to be responsible for the male refractory period is prolactin, which represses dopamine, which is responsible for sexual arousal. Because of this, there is
Psychological refractory period caffeine intake have also been investigated. PRP is a product of the psychological refractory period paradigm, a paradigm in which two different stimuli are presented in rapid succession, each requiring a fast response. Stimulus onset asynchrony, the time that lapses between the presentations of the two stimuli, acts as the "independent variable" in this paradigm, and the reaction time to the second stimulus acts as the "dependent variable". An example of a PRP paradigm might be that there is a task 1 which requires participants to push the keyboard-letter 'n' with the right index finger when a square frame was