A chemical secreted by an animal, especially an insect, that affects the development or behavior of other members of the same species, functioning often as a means of attracting a member of the opposite sex.
Sexual motivation, often referred to as libido, is a person's overall sexual drive or desire for sexual activity. This motivation is determined by biological, psychological, and social factors. In most mammalian species, sex hormones control the ability to engage in sexual behaviors. However, sex hormones do not directly regulate the ability to copulate in primates (including humans); rather, they are only one influence on the motivation to engage in sexual behaviors. Social factors such as work and family also have an impact, as do internal psychological factors like personality and stress. Sex drive may also be affected by medical conditions, medications, lifestyle stress, pregnancy, and relationship issues. In this section, however, we will examine the biological factors that influence sexual motivation.
Biologically, sexual motivation is influenced by hormones such as testosterone, estrogen, progesterone, oxytocin, and vasopressin. In males, testosterone appears to be a major contributing factor to sexual motivation. Interestingly, testosterone levels in males have been shown to vary according to the ovulating state of females. Males who were exposed to scents of ovulating women recorded a higher testosterone level than males who were exposed to scents of nonovulating women. The hormones oxytocin and vasopressin may also help to regulate males' sexual motivation. Oxytocin is released at orgasm and promotes both emotional bonding and sexual pleasure. Based on the pleasure model of sexual motivation, the increased sexual pleasure that occurs following oxytocin release may encourage motivation to engage in future sexual activities. Vasopressin is involved in the male arousal phase, and the increase of vasopressin during erectile response may be directly associated with increased motivation to engage in sexual behavior.
The relationship between hormones and female sexual motivation is not as well understood, largely due to the overemphasis on male sexuality in Western research. Estrogen and progesterone typically regulate motivation to engage in sexual behavior for females. Estrogen, in particular, has been shown to correlate positively with increases in female sexual motivation, and progesterone has been associated with decreases in motivation. The levels of these hormones rise and fall throughout a woman's menstrual cycle, and females at different stages of their cycle have been shown to display differences in sexual attraction. Research suggests that testosterone, oxytocin, and vasopressin are also implicated in female sexual motivation in similar ways that they are for males, but more research is needed to understand these relationships.
A pheromone is a secreted or excreted chemical factor, usually in the form of a scent, that triggers a social response in members of the same species. These chemicals are capable of acting outside the body of the secreting individual to impact the behavior of another individual. In animals and insects, sex pheromones indicate the availability of the female for breeding. Male animals may also emit pheromones that convey information about their species and genotype . While most research on pheromones has been conducted on animals and insects, smell and body odor is known to play a role in sociosexual behavior of humans. Studies have suggested that humans might use odor cues associated with the immune system in order to select mates.
There is no universally agreed measure of what is a healthy level for sex. Sexual motivation can be measured using a variety of different techniques, including self-report measures such as the Sexual Desire Inventory. These are subject to false results, however, if people feel compelled to represent socially desirable results. Sexual motivation can also be implicitly examined through frequency of sexual behavior.