Menstrual synchrony by chance when there is menstrual cycle variability. Yang and Schank argued that when there is cycle variability (i.e., either women have irregular cycles, have cycles of different frequencies, or both), most women will have the opportunity to experience synchrony even though it is a result of cycle variability and not a result of a mechanism such as the exchange of pheromones. For example, consider two women A and B. Suppose A has menstrual cycles that are 28 days long and B has cycles that are 30 days long. Suppose further that when A and B become close friends, B
Human sexual response cycle Human sexual response cycle The human sexual response cycle is a four-stage model of physiological responses to sexual stimulation, which, in order of their occurrence, are the excitement phase, plateau phase, orgasmic phase and resolution phase. This physiological response model was first formulated by William H. Masters and Virginia E. Johnson, in their 1966 book "Human Sexual Response". Since then, other human sexual response models have been formulated. The excitement phase (also known as the arousal phase or initial excitement phase) is the first stage of the human sexual response cycle, which occurs as a result of physical or mental