Freud ) in Freud's structural model of the soul, referring to his rider metaphor: The head symbolizes the
ego (principle of reality); the animal body the
id (pleasure principle). Dual in the same way, the libido branches out from the id into two main areas: the mental urge to know (up), and the bodily urge to act (down). Both combine to act through the ego in order to fulfil the needs of the id. This includes perception and assessment of inner/outer reality, and is based on unpleasant increase and pleasurable reduction of tension in libidinal energy ( “hunger” and “satiety” in general). Ultimately, satisfaction of the needs leads to experiences (by muscle control) that the superego internalises through
imprinting. The superego contains our socialisation, that takes place during childhood. If it support the id's instinctual needs, the organism remains mentally healthy – the 'rider' carries out the will of his 'animal' "as if it were his own".
Sigmund Freud defined libido as "the energy, regarded as a quantitative magnitude... of those instincts which have to do with all that may be comprised under the word 'love'." It is the instinctual energy or force, contained in what Freud called the
id, the strictly unconscious structure of the
psyche. He also explained that it is analogous to hunger, the will to power, and so on insisting that it is a fundamental instinct that is innate in all humans. Freud pointed out that these libidinal drives can conflict with the conventions of civilised behavior, represented in the psyche by the
superego. It is this need to conform to society and control the libido that leads to tension and anxiety in the individual, prompting the use of
ego defenses which channel the psychic energy of the unconscious drives into forms that are acceptable to the ego and superego. Excessive use of ego defenses results in
neurosis, so a primary goal of
psychoanalysis is to make the drives accessible to
consciousness, allowing them to be addressed directly, thus reducing the patient's automatic resort to ego defenses. Freud viewed libido as passing through a series of
developmental stages in the individual, in which the libido fixates on different erogenous zones: first the
oral stage (exemplified by an infant's pleasure in nursing), then the
anal stage (exemplified by a toddler's pleasure in controlling his or her bowels), then the
phallic stage, through a
latency stage in which the libido is dormant, to its reemergence at puberty in the
genital stage (
Karl Abraham would later add subdivisions in both oral and anal stages.). Failure to adequately adapt to the demands of these different stages could result in libidinal energy becoming 'dammed up' or
fixated in these stages, producing certain pathological character traits in adulthood.
Jung Swiss psychiatrist
Carl Gustav Jung identified the libido with psychic energy in general. According to Jung, 'energy', in its subjective and psychological sense, is 'desire', of which sexual desire is just one aspect. Libido thus denotes "a desire or impulse which is unchecked by any kind of authority, moral or otherwise. Libido is appetite in its natural state. From the genetic point of view it is bodily needs like hunger, thirst, sleep, and sex, and emotional states or affects, which constitute the essence of libido." It is "the energy that manifests itself in the life process and is perceived subjectively as striving and desire." He describes libido as manifesting through five primary instincts: hunger, sexuality, activity, reflection, and creativity. Duality (opposition) creates the energy (or libido) of the psyche, which Jung asserts expresses itself only through symbols. These symbols may manifest as "fantasy-images" in the process of psychoanalysis, giving subjective expression to the contents of the libido, which otherwise lacks any definite form. Desire, conceived generally as a psychic longing, movement, displacement and structuring, manifests itself in definable forms which are apprehended through analysis.
Further psychological and social viewpoints A person may have a desire for sex, but not have the opportunity to act on that desire, or may on personal, moral or religious reasons
refrain from acting on the urge. Psychologically, a person's urge can be
repressed or
sublimated. Conversely, a person can engage in sexual activity without an actual desire for it. Multiple factors affect human sex drive, including stress, illness, pregnancy, and others. A large 2022 review, using more than 620,000 people and 211 studies, found that men had higher sex drives than women on average, and that one-third of women (30-35%) had a higher sex drive than the average man. The study found an 80% overlap in the sex drives of men and women, and that the effects of the difference were "medium" in size. However, a 2024 comprehensive review challenged the interpretation that these self-reported differences reflect inherent biological differences in sexual motivation. Touraille and Ågmo examined evidence from both humans and non-human mammals, finding that sex differences in sexual motivation depend heavily on measurement methods. In rodent studies, when sexual motivation was measured through approach behaviors in procedures without aversive elements, no sex differences emerged. Earlier studies using the Columbia Obstruction Box (where animals crossed electrified grids to reach mates) actually found female rats were more motivated than males, or showed no difference—never finding males superior to females. In non-human primates, observational data from species including gray mouse lemurs, chimpanzees, and bonobos showed comparable rates of sexual activity and numbers of partners between males and females, with both sexes displaying promiscuous mating patterns. In humans, when sexual motivation is measured through automatic physiological responses—including genital arousal to sexual stimuli, attentional allocation to sexual content, implicit motivation tests, and spinal reflex facilitation—sex differences consistently disappear. Touraille and Ågmo suggest that the sex differences found in self-report questionnaires may reflect social learning of sexual scripts, response bias due to gender norms, and the documented lower quality of sexual experiences (including lower orgasm rates and higher rates of pain during intercourse) reported by women, rather than reflecting true differences in underlying sexual motivation. They conclude that males and females across mammalian species, including humans, appear similar with regard to the inherent intensity of sexual motivation. Other studies have found that women report similar sexual habits as men, such as masturbation frequency, under the impression of a lie detector. The study reported that "sex differences in self-reported sexual behavior (masturbation) were negligible in a bogus pipeline condition in which participants believed lying could be detected." A 2012 study found that, in couples who has been together at least a year, differences in sex drive were non-significant and more similar than different. Another 2012 study found that testosterone did not account for sexual differences between men and women. Certain psychological or social factors can reduce the desire for sex. These factors can include lack of privacy or
intimacy,
stress or
fatigue, distraction, safety social stigma (in women, it can account for a large part of rejecting sex), or depression. Environmental stress, such as prolonged exposure to
elevated sound levels or
bright light, can also affect libido. Other causes include experience of sexual abuse, assault, trauma, or neglect, body image issues, and anxiety about engaging in sexual activity. Women whose first sexual experience was pleasant report the same sex drive as men. Individuals with
post-traumatic stress disorder (PTSD) may find themselves with reduced sexual desire. Struggling to find pleasure, as well as having trust issues, many with PTSD experience feelings of vulnerability, rage and anger, and emotional shutdowns, which have been shown to inhibit sexual desire in those with PTSD. Reduced sex drive may also be present in trauma victims due to issues arising in sexual function. For women, it has been found that treatment can improve sexual function, thus helping restore sexual desire. Depression and libido decline often coincide, with reduced sex drive being one of the symptoms of
depression. Those with depression often report the decline in libido to be far reaching and more noticeable than other symptoms. == Biological perspectives ==