How Sexual Desire Works- The Enigmatic Urge

by Frederick Toates

  (predominantly heterosexual woman, age 18; Meston and Buss, 2009)

  Seeking a boost to arousal by breaking boundaries of conventionality is dramatically illustrated by such activities as voyeurism, frotteurism (uninvited rubbing of the body against another, a hazard for women on the Japanese subway system) and exhibitionism, to be described later.

  That danger can trigger desire in certain women was evidenced by the presence of devoted and sexually aroused groupies at the trial of the serial sex-killer Richard Ramirez (Carlo, 2010). One reported (p. 291):

  It used to turn me on …he was so dangerous and so near …

  Large amounts of fan-mail from eager women overseas were witnessed by prison guards, this not being an isolated case (Berry-Dee, 2003; Buss, 2005; O’Brien, 1985). The biographer of the Austrian serial killer Jack Unterweger speculated that the attraction that women showed towards him was in large part due to the sense of danger that he triggered (Leake, 2007). A report of his trial describes some twenty adoring women in the courtroom.

  The forbidden seems to be a crucial element in the sexual turn-on of some people, characterized by Doidge (2007) with the term ‘perversion’, where such individuals (p. 124):

  often celebrate and idealize humiliation, hostility, defiance, the forbidden, the furtive, the lusciously sinful, and the breaking of taboos; they feel special for not being merely ‘normal’. These ‘transgressive’ or defiant attitudes are essential for the enjoyment of perversion.

  For some, physical pain can lower desire and sexual performance, whereas for others it can increase sexual desire. Which of these effects it has depends in part upon earlier experience of pain (Ford and Beach, 1951). Cultural factors play a role here; where a society traditionally sees a certain amount of pain (e.g. from scratching and biting) as being an integral part of the sexual act, then the individual is more likely to exploit pain in the service of sexual arousal. For individuals in other cultures, pain will tend to be a turn-off. This again points to the central role of learning in sexual desire and arousal.

  Sexual arousal, experimental evidence and theories

  General principles

  What do hard physical exertion, genital/sexual arousal and negative emotions such as anger (described later) and fear have in common? They all activate the sympathetic branch of the autonomic nervous system (ANS) (Zillmann, 1986).2 Thereby, they also share much of the underlying bodily reaction, for example elevated heart rate, adrenalin secretion and blood pressure (Kinsey et al., 1953; Zillmann, 1984, 1986).3

  An emotion such as fear can sometimes enhance sexual arousal, since the arousal of the ANS that it triggers becomes available to sexual arousal (Barlow, 1986). Even simultaneously with experiencing fear, this effect can sometimes be seen. Also, autonomic arousal, such as that induced by vigorous exercise or fear, does not dissipate immediately when such triggers are removed, so it is potentially available to enhance later sexual attraction (Zillmann, 1984). Murstein (1986, p. 108) concluded:

  All in all, it appears that men aroused by a neutral stimulus4 can be influenced to misattribute the source of arousal if the salience of the neutral arousal is minimized and the salience of cues regarding the attractiveness of the target is maximized.

  Reciprocally, consider when the triggers for anger are present. If any arousal arising from an immediately preceding sexual stimulus or from physical exertion is still present, this can contribute to anger (Zillmann, 1986).

  People tend to make sense of their bodily reaction by labelling it in terms of its most likely cause. Where there is ambiguity, they might misperceive the cause of their arousal. To what the subjective arousal is attributed depends in part on the time interval between the arousal trigger and the attribution process. If this is short, attribution is made to the correct stimulus, a bit longer and it is sometimes made to some other candidate, but if left too long arousal dissipates and there is no effect of the initial arousal (Zillmann, 1984, 1986).

  Arousal induced by physical exertion, humour or exposure to erotic stimulation tends to make an attractive partner still more attractive but an unattractive partner still more unattractive (White et al., 1981). Arousal is interpreted in terms of the available stimulus. Following a bout of strenuous exercise with obvious cues such as heavy breathing still present, arousal is likely to be attributed correctly to the exercise. A bit later, if sexual cues are present the arousal actually arising from exercise can lock into interaction with the sexual cues and contribute to sexual desire.

  Fear

  An individual who takes a ride on a fear-evoking fairground amusement subsequently tends to see an attractive person as being even more attractive. This is unless the aroused individual has correctly attributed their heightened arousal to the ride (Zillmann, 1984). Laboratory experimentation indicates that under some conditions a prior experience of anxiety can be followed by increased genital arousal (Hoon et al., 1977).

  A study in Vancouver, known as the ‘rope bridge experiment’ (Dutton and Aron, 1974), is a classic of social psychology but must surely rank amongst psychology’s more eccentric designs. The researchers wondered whether the bodily arousal associated with a naturally induced fear would increase the attraction felt for another person. So, they located a 450-foot-long suspension bridge, constructed of wooden boards attached to wire cables, that crossed the Capilano River. What were described as its ‘arousal-inducing features’ included a tendency to sway and wobble, which created the impression that the unwitting participants were about to fall 230 feet to rocks below. It is easy to imagine that this would be fear-inducing: it certainly is even for the present author at a safe distance.

  A female confederate of the experimenters approached young males making the crossing and asked for their participation in a study. Subsequently, sexual themes appeared in their interpretation of a picture and they tended to contact the confederate after this. The suggestion is that the fear increased their attraction for her. The control condition was to do the same thing with males crossing a firm and stable bridge just 10 feet above a stream and was associated, it would seem, with lower sexual motivation. Fisher (2004) suggests that the men crossing the rope bridge might have had a surge of dopamine activation.

  The experiment has provoked controversy. The result is compatible with the authors’ conclusion but so can it be fitted to other interpretations. Any woman sufficiently courageous and risk-seeking to cross such a bridge might have been thought to be adventurous and therefore an interesting contact. It might have been that the sight of the woman served to reduce anxiety (Kenrick and Cialdini, 1977).

  What is sexual arousal?

  Anyone who has experienced sexual arousal knows something about it, but how is it to be defined and measured exactly? This has proven problematic. At least three different types of definitions have been proposed:

  Sexual arousal is the same as sexual desire, in which case we would hardly need two words to describe the same thing. Sachs (2000) argues persuasively that arousal and desire are distinct processes but with reciprocal excitatory links (‘strong positive feedback’) between them.

  Sexual arousal is the reaction of the genitals, in terms of the amount of blood flowing there. Genital swelling is known as ‘vasocongestion’, perhaps not the most erotic of terms. I shall use the possibly more palatable ‘genital swelling’.

  The definition which is favoured here: sexual arousal is something situated between desire and the genital reaction, which both influences, and is influenced by, desire and the genital reaction.

  Arousal is not the same as desire. There can be serious failures of arousal as indexed by the genital reaction even in people who report normal levels of desire (Nobre and Pinto-Gouveia, 2008). Conversely, asexuals can exhibit sexual arousal and pleasure but feel no sexual desire directed to another individual (Brotto and Yule, 2011). Women with persistent genital arousal disorder experience unwanted arousal in the absence of desire (Leiblum and Nathan, 2001). As described in Chapter 7, desire might trigge
r sexually-directed behaviour (contact-making, searching one’s memories for erotic associations) even in the absence of any felt arousal. Bancroft (2009) speculated that sexual arousal appears first in development and desire is then shaped from this by linking arousal to attractive others. Arousal might be construed as normally providing a modulator between genital touch and the pleasure derived from this, which then links to desire. Arousal is also associated with preparing the body for action. This includes elevating heart rate and putting the muscles involved with the body into a state of readiness (Both et al., 2005).

  Objective and subjective arousal

  General features

  For men, the objective measure of sexual arousal, the swelling of the penis, correlates well with their subjective feeling of sexual arousal. Although the correspondence between objective and subjective is not perfect, it is much closer in men than in women (Chivers and Bailey, 2005; Laan and Janssen, 2006). In women, the objective arousal response of the genitals is generally measured by inserting an apparatus into the vagina to measure the blood flowing there (Bancroft and Graham, 2011). In response to sexual stimuli, there is highly likely to be an increase in this blood flow, a reliable automatic reaction. Objective arousal tends to occur to a wide range of sexual stimuli, for example an erotic film, including even a film of pygmy chimpanzees copulating! Objective arousal is seen whether or not the woman finds the stimuli attractive and even when her subjective reaction is negative. Presumably, rather few women would opt for the sight of copulating chimpanzees as an aphrodisiac. Similarly, women occasionally report vaginal lubrication even when the feeling of subjective arousal is lacking (Laan and Janssen, 2006).

  In both sexes, it appears that subjective sexual arousal, the consciously felt level, depends upon a combination of two sources of information (Janssen et al., 2000; Spiering and Everaerd, 2006):5

  1 Automatic (‘low-level’) arousal, as reflected in the state of the genitals and other bodily reactions such as heart rate. This is, at first, a fast, non-conscious response, which is triggered by sexual stimuli (e.g. an erotic film) and is measured objectively as increased blood flow at the genitals (Ponseti and Bosinski, 2010). Information on this bodily state is transmitted to the brain. If the bodily arousal persists at sufficient strength, the signal of it contributes to conscious awareness of arousal. Even when a sexual stimulus is presented visually for such a short duration that the person is unaware consciously of it, there is still some arousal response at the genitals (Both et al., 2008a; Ponseti and Bosinski, 2010; Spiering and Everaerd, 2006).

  2 A subjective (‘high-level’) cognitive interpretation of the situation, a form of labelling – is the detected bodily condition specifically one of sexual arousal? Subjective arousal depends upon the meaning attached to the bodily state and the apparent sexual stimulus that triggers it. The subjective feeling calls upon attitudes, intentions, memories, beliefs and so on.

  To summarize, a sexual stimulus triggers: (a) objective bodily arousal and (b) the search for an explanation for this arousal (Everaerd et al., 2000a). The same stimulus might tend to trigger arousal that is labelled as anger or fear, so the emergence of the sexual label is not inevitable. Learning is involved in linking external sexual stimuli and bodily sensations in order to yield subjective sexual arousal. The combined role of factors 1 and 2 above exemplifies how any attempt to allocate relative weights to which is most important in human sexuality, biology or social environment, is misguided. A biological factor is labelled in terms of social meaning.

  According to one interpretation, sexual desire does not lead to sexual arousal but arousal can lead to sexual desire, depending upon an interpretation process (Laan and Both, 2008). Maybe it is safest to see a reciprocal relationship between desire and arousal, where each can influence the other, that is desire ↔ arousal.

  Gender differences

  How is the lack of correspondence between objective and subjective arousal in women to be explained? Is the signal from the genitals to the brain weaker in women, so that they are less well informed on the arousal of their genitals? This appears not to be so. A region of brain, the insula, is excited by bodily reactions including those triggered by erotic stimuli. It shows equal excitation to an erotic film in men and women (Karama et al., 2002). So, what can explain the gender difference in subjective arousal? As a general factor, women are less good than men at monitoring their bodily conditions (Pennebaker and Roberts, 1992).

  A number of interacting processes could be implicated (Laan and Janssen, 2006). It might be that, although the signals reaching the brain are little different between men and women, there is a sex difference in the tendency of these signals to enter conscious processing. In addition to internal signals passing from the genitals to the brain, a boy’s genital arousal is more evident externally, that is visually and in touching by the hands, than is a girl’s. In Western countries, fewer girls than boys masturbate, which could be a learning experience linking genital sensations to erotic labelling (Laan and Janssen, 2006).

  Laan and Both (2008) studied objective genital and subjective responses to two erotic films. Each contained depictions of explicit sexuality. One was ‘female-friendly’ and took the woman’s perspective, including time spent showing the development of the relationship between the actors. The other was ‘male-typical’, with a focus upon the male perspective and the genitals. Males did not differ in their response to the two films. For women, the subjective feeling was greater for the ‘woman-friendly’ film as compared to the ‘man-friendly’, although the genital response was the same for both. Such studies suggest that pharmaceutical interventions to treat female sexual arousal disorders, which target the genitals, are likely to be disappointing. Rather, the emotional and social context would be better targeted.

  A wide range of sexual stimuli that are presented so briefly that they do not reach conscious awareness nonetheless tend to trigger some genital arousal in women (Ponseti and Bosinski, 2010). For men, the range of stimuli having this effect is more limited than for women.

  It appears that, whereas increased activity by the sympathetic branch of the autonomic nervous system increases a woman’s sexual arousal as measured by vaginal blood flow, it decreases men’s sexual arousal, as measured by erectile capacity (Meston and Buss, 2009) (though see also Chapter 20).

  The role of learning and memory

  Sexual arousal depends in part upon learning and this can operate at more than one level (Hoffmann, 2007; Spiering and Everaerd, 2006). Some learned associations operate quite automatically and the person might have no conscious awareness of their presence or role. However, conscious awareness that conditioning is being attempted can also enhance its strength.

  In males, sexual arousal, as measured by the erectile reaction of the penis, can be conditioned. Plaud and Martini (1999) paired a neutral stimulus, an image of a penny jar, a number of times with an image of a sexually attractive female. After this, just presenting the image of a penny jar on its own triggered an erectile response.

  A particular location or odour might in the past have been associated with arousal or conversely with fear and now acts on objective arousal below the level of conscious awareness. Hans Eysenck told a tale of a patient who was somewhat baffled by being sexually dysfunctional in a new partner’s bedroom and it was found that the wallpaper was the culprit, because the paper’s pattern had earlier been associated with an assault. True to form, Eysenck could not resist adding that the solution required the professional services not of a psychoanalyst but of a paperhanger. I think that the story was apocryphal but, even if so, it serves to make the point rather well!

  By contrast, other memories can be tapped in a fully conscious mode and they might increase or decrease subjective sexual arousal. For example, fantasies of past sexual experiences might be exploited to enhance current arousal. Conversely, the conscious recall of such things as a memory of a pledge of fidelity, or of a recent advertisement on sexual health or of having forgotten to
take the contraceptive pill might lower arousal.

  When objective and subjective match

  Objective and subjective factors might act in the same mutually reinforcing direction. Women commonly report the genital swelling with blood in such terms as ‘tingling’ and ‘throbbing’ and being sexually motivated to ‘resolve the build-up’. This is sometimes described in such terms as an itch that needs scratching (Meston and Buss, 2009, p. 32). To some extent, the contractions of orgasm reverse this state of genital swelling. If orgasm does not occur and the swelling is not resolved, this can lead to an uncomfortable feeling of frustration.

  When subjective is at odds with objective

  In women, hard physical exercise, a trigger to increased sympathetic activity, increased objective measures of arousal triggered by an erotic film but not subjective arousal (Meston and Gorzalka, 1996).

  If the meaning of the situation is negative, for example disapproval, in spite of there being a genital arousal response, subjective arousal can be negative. Under conditions of sexual dysfunction, the meaning-related information, involving say guilt or performance anxiety, could act in the opposite direction to the more automatic genital response. For women with sexual arousal disorder, the objective measure, the genital response to an erotic video, does not differ from that of control women but their subjective feeling is less positive or even negative (Both et al., 2011).

  Victims of sexual assault, male and female, sometimes show objective sexual arousal even though subjectively they hate the experience (Levin and van Berlo, 2004). It has been speculated that this automatic genital reaction evolved as a means of protecting women from injury and infection during intercourse (Bancroft and Graham, 2011; Chivers and Bailey, 2005), though this might not explain its existence in males too. The arousal accompanying sexual assault might also be in part a spill-over of arousal from fear. Assailants sometimes wrongly claim that their victim’s reaction shows evidence of consent rather than resistance.