How Sexual Desire Works- The Enigmatic Urge

by Frederick Toates

  A sample of men viewing a film depicting a rape scene showed relatively high levels of arousal but low levels of desire (Janssen et al., 2002).

  Biological bases

  A brain region, the insula, is responsive to bodily states such as fear, anger, sadness, happiness and disgust, as well as sexual arousal (Stoléru and Mouras, 2006). Pointing to overlap in brain regions embodying arousal, one study found that brain regions activated by recalling an erotic episode were similar to those excited when participants recalled their participation in a competitive event or success in a sporting challenge (Rauch et al., 1999). When sex hormones are deficient, this region fails to respond to erotic stimuli.

  Therapeutic implications

  Sexual behaviour is often accompanied by thoughts that automatically enter conscious awareness, triggered it would appear by the particular sexual/emotional state (Barlow, 1986; Nobre and Pinto-Gouveia, 2008). Some of these are erotic, of a kind that would be expected to increase arousal. Other thoughts concern personal inadequacies such as loss of physical attraction and performance failure, which might be expected to lower arousal. Not surprisingly, people suffering from sexual dysfunction report many more negative thoughts than do functioning controls. What causes what? Logically we might suppose that the direction of causation can be reciprocal (Barlow, 1986). This would give rise to either a virtuous circle of self-reinforcing sexual cues and arousal, or a vicious circle, for example the sexual context triggers intrusion of negative (failure-related) thoughts, which lower arousal and increase the intensity and frequency of the negative thoughts. A fear of performance failure, particularly on the part of men, can trigger a vicious circle, whereby it causes a focus of attention upon the genitals such as to lead to a self-fulfilling prophecy.

  One might suppose that distraction (done experimentally by presenting information irrelevant to the sexual activity, such as listening to a non-erotic reading from a novel while watching an erotic movie) would lower the genital response to sexual stimuli. This is indeed the case for sexually functioning men (Barlow, 1986). They are assumed to have their focus normally on such things as the success of their performance and distraction draws them from this task. However, for men with erectile dysfunction, distraction leaves the genital response to sexual stimuli unaffected.

  This makes sense in terms of levels of control. Their cognitive processing is assumed to be occupied normally with thoughts concerning the fear of performance failure. So, it seems that engaging this capacity does not impair things any further. In principle, it might even improve erectile capacity.

  The link with desire

  Sexual desire and subjective sexual arousal are often perceived in women to be closely connected (Graham, 2010). Disorders of the one correspond to a considerable extent with disorders of the other. So are desire and arousal the same thing? It could be worth distinguishing (a) arousal as the subjective awareness of bodily changes, not exclusively at the genitals, and (b) desire as outward directed goal-seeking that relates to the intention to engage in sexual action (Laan and Both, 2008), though desire does not invariably lead to the wish to have sex (Meana 2010, citing Regan and Berscheid). In such terms, desire would relate to subjective arousal but would not be synonymous with it. There is not invariably a sequence of first desire (‘interest’) and then arousal, since in some cases arousal is perceived first and desire felt secondly. Desire and genital arousal can lock into a virtuous circle, as two people escalate their sexual activity. Escalation is associated with increasing expectations of success, whereby attention to the genitals reinforces desire and the positive expectation (Wiegel et al., 2006).

  Valins (1970) investigated the effect of changes in perceived heart rate on men’s assessment of the attractiveness of women. Participants heard what they thought was their heart rate played over ear-phones. As this increased, so did perceived attractiveness. This suggests a cognitive process of making sense of the reaction, that is my heart rate has accelerated so she must be attractive.

  The discussion now turns to the consequences derived from sexual behaviour.

  In summary

  It is suggested that arousal lies between sexual desire and the reaction of the genitals.

  Subjective arousal should be distinguished from objective arousal as measured at the genitals.

  Particularly in women, there is dissociation between objective arousal, which is triggered automatically, and subjective arousal which involves meaning and goals.

  Ten The consequences of sexual behaviour and associated expectations

  Nature has placed mankind under the governance of two sovereign masters, pain and pleasure. It is for them alone to point out what we ought to do, as well as to determine what we shall do.

  (Jeremy Bentham, 1781/1988, p. 1)

  Evidence suggests that they might not be quite the sovereign masters that Bentham supposed, though pleasure and pain feature large in any explanation of human sexuality.

  Basics

  Engaging in sexual behaviour has immediate consequences and these are generally assumed to influence future sexuality in terms of desire and the chances of sexual behaviour being repeated (Bancroft, 2009). Consequences of behaviour that encourage us to repeat the behaviour are known as ‘reinforcers’ (Chapter 2). Conversely, the consequences can be such as to reduce the future tendency to repeat the behaviour, in which case they would be described as ‘punishing’.1 Viewed in evolutionary terms, reinforcement encourages people to repeat behaviour that has served reproduction, whereas punishment persuades them to resist, stop, take stock of the situation and change behaviour. This chapter looks into the details of these immediate consequences of sexual behaviour and their link to desire.

  Subjectively felt pleasure and displeasure form an obvious feature of the design of human sexuality. Pleasure normally accompanies behaviour that is described as ‘reinforcing’, while displeasure is associated with ‘punishment’. Pleasure plays a role in keeping behaviour going – it can create the desire to enhance pleasure by escalating the intensity of the activity and encourages a repeat in the future. The reader not familiar with the esoteric world of psychology might wonder why the terms ‘reinforcement’ and ‘punishment’ are used, when pleasure and pain would seem simpler. There are two reasons:

  The language is based upon behaviour and applies equally to humans and non-humans, since we cannot get verbal reports from non-humans on their experience of pleasure or pain.

  A consequence of behaviour might be reinforcing even though it is not pleasurable.2

  Three features of sexual behaviour can be associated with such consequences:

  Approach behaviour

  Sexual contact

  Orgasm

  The next three sections consider these.

  Approach behaviour

  As a general principle, pleasure is felt when things go according to desires and plans, whereas displeasure is felt when a plan is thwarted or things are significantly below expectations (Carver and Scheier, 1990; Panksepp, 1982). This obviously fits sexual behaviour. Being in a situation of perceived and desired sexual opportunity, detection of a move towards the goal is associated with pleasure, whereas a sign of rejection and movement away from the goal is associated with displeasure. In this stage, pleasure is derived from such things as making a date, receiving a confirmatory telephone call and the date arriving at the agreed location.

  Pleasure usually requires not only progress towards a goal but a certain speed of progress being made. Depending upon the overall set of goals, particularly strong pleasure might be felt if progress is faster than expected or an obstacle to progress is suddenly removed. Of course, goals can conflict and this could explain people’s experience of rapidly alternating positive and negative affect (Carver and Scheier, 1990). Movement towards one goal, for example a new sexual liaison, might bring pleasure but simultaneously the movement away from a higher goal of an ‘ideal self’, for example to maintain reserve, could bring displeasure.

  In o
ne study, young people gave readings of their levels of affect prior to and following sexual intercourse (Shrier et al., 2010). Positive affect increased in the hours prior to intercourse, presumably in anticipation of the hedonic event and stayed elevated for some hours afterwards. Negative affect was lowered for some hours after the event.

  Successful movement towards a sexual goal appears to be a good example of a very general principle: having control of a situation is positively reinforcing. Under conditions of stress, exertion of control is associated with a boost in dopaminergic activity in the nucleus accumbens, whereas a failure of control in an aversive situation is associated with a lowering of dopaminergic activity (Cabib and Puglisi-Allegra, 2012). Such dopaminergic activation would be expected to reinforce the action, increasing the tendency to repeat it in the future. It might also be expected to blend with dopaminergic activation arising from sexual desire, enhancing the lure of the sexual incentive.

  Engaging in sexual activity

  I could never get my pleasure and satisfaction of her unless she got hers of me at the same time.

  (D. H. Lawrence, 1928/1993, p. 214)

  Pleasure derives from kissing, and touching the other’s body and intercourse, as well as, in the case of empathetic people, signs of pleasure in the partner. As Simon and Gagnon (1987, p. 370) note: ‘The sexual actor must not only anticipate and orchestrate the behavior of the other(s), he or she must also anticipate and orchestrate the feelings communicated however uncertainly by that behavior.’

  Whether stimulation arising from the erogenous zones of the body is felt as pleasurable depends not only upon the messages sent from these zones to the brain but also upon processing by the brain, indicating the presence of sexual desire. The pleasure of sexual stimulation by tactile contact depends, of course, not only on the signals set up by touch but also the context (Everaerd et al., 2000b). If desire is absent or lost, or arousal not yet sufficiently high, then the signal could be arising in the same way at the genitals but this might contribute to displeasure rather than pleasure. An obvious example is engaging in sexual behaviour under duress or simply out of a sense of duty. Similarly, for a heterosexual male, tactile stimulation by a female might well be very pleasurable, whereas by another male, it would probably be felt as aversive. Pleasure at this stage might be intrinsic to the activity or conditional upon the detection of an escalation of intensity.

  Orgasm

  This is, of course, something unique to sexual behaviour. It appears that orgasm is a powerful positive reinforcer, encouraging the individual to repeat the behaviour leading to it (Fisher, 1986). An obvious feature of orgasm is a sudden reduction of tension in the body and a return to a more normal state (Kinsey et al., 1948). A powerful orgasm would have the effect of consolidating desire, whereas, if the orgasm is substandard, failing to meet expectations, it might move the individual in the direction of aversion (Fisher, 1986). This emphasizes the role of expectations and interpretations. The more reward obtained from sexual behaviour, the higher the frequency of showing it (Ågmo, 2007). In some cases loss of desire (so-called hypoactive sexual desire) could arise from frustrated expectations, such as failure of orgasm. This can be situation-specific: a person might lose interest in a regular partner but find desire aroused by a different partner. A context such as a particular bedroom might set the scene for a loss of desire, whereas a change of environment revives it. The person with loss of desire can show actual aversion to particular sexual stimuli. Certain therapeutic techniques for loss of desire are based on the principle that any sexual interaction needs to result in reward for both partners. Ågmo sees all this as evidence in favour of an incentive motivation model.

  Male orgasm is a powerful reward to encourage the male to persist until this occurs, thereby encouraging ejaculation and permitting fertilization. The function of female orgasm is not so obvious, which has led some to suggest that maybe it has no function and is just an evolutionary by-product. A function has been suggested in terms of (a) moving sperms upwards towards where they can meet the egg cell, (b) reinforcing sexual activity and (c) consolidating the pair bond. Another idea is that female orgasm triggers the male to ejaculate (Meston and Buss, 2009).

  Biological bases of sexual pleasure

  This subject can best be addressed in a broader context of pleasure, since the relevant experiments mainly involve feeding and drugs. The existence of dedicated brain mechanisms underlying pleasure is indicative of its role in evolution (Berridge and Kringelbach, 2013).

  Dopamine is involved in the wanting phase of motivation (Chapter 8). This has been established in the context of pleasure reactions to food in the mouth. However, dopamine might also have a role in the pleasure derived from anticipating and achieving a goal (Klein, 1987), such as getting to a place where sexual contact may take place. We simply don’t yet know. Some suggest that dopamine has a role in ‘enthusiastic positive excitement’ and ‘euphoric engagement with the world’ (Alcaro et al., 2007), which is compatible with the idea that dopamine mediates the pleasures associated with approaching and finally achieving a goal. As introduced in Chapter 8, dopamine levels increase in the phase of goal-directed behaviour leading to a goal and then decline when the goal is reached (Blackburn et al., 1992). This raises the possibility that a rise and then fall in dopamine level is felt as pleasurable.

  Rather as with wanting, the brain regions that underlie liking are organized in a layered (‘hierarchical’) way (Berridge and Kringelbach, 2013). It appears that regions below the level of the cortex form a basis of the ‘raw’ experience of pleasure and may be common across a number of species (Chapter 2). One of these, the nucleus accumbens,3 has already been described in the context of wanting. It has sub-regions dedicated to wanting and pleasure. Regions of the prefrontal cortex4 also play a role in pleasure, probably via projections to the subcortical regions. The prefrontal cortex is expanded in humans relative to other species and thereby appears to contribute to the peculiarly human and meaning-related aspects of pleasure. It is said to ‘encode’ pleasure and the region’s activity probably plays a role in the recall of past hedonic experiences. Much of the brain machinery of pleasure appears to serve various different pleasures (Berridge and Kringelbach, 2013). This would be relevant to the observation that some individuals take drugs such as cocaine to enhance sexual experience (Chapters 2 and 17).

  From research on feeding, it appears that substances called ‘opioids’ are involved in the pleasure derived from, amongst other things, the taste of food. Opioids are the natural equivalents of the opiates, drugs such as heroin. These act in the sub-region of the nucleus accumbens termed a ‘hedonic hot-spot’, to mediate a range of pleasures (Berridge and Kringelbach, 2013). The fact that some people use masturbation as a means of gaining pain relief (Marchand, 1961) also suggests a basis in opioids.

  Levels of the substance oxytocin in the blood increase during sexual activity and particularly at orgasm (Carmichael et al., 1994). Oxytocin could play a role in the pleasure of orgasm, as well as tending to inhibit immediately following sexual activity. Opioids are also simultaneously involved in orgasmic pleasure and post-orgasmic inhibition of further sexual activity (Georgiadis et al., 2012). Feedback to the brain from the muscular contractions that accompany orgasm in men and women might also be implicated in the intense pleasure as well as the satiety effect. The pleasure of sex can sometimes be used as a soothing balm as in post-conflict ‘make-up sex’ (Dewitte, 2012), which might owe something to oxytocin.

  Link between wanting and arousal/liking

  Usually pleasure and wanting are closely linked: we like what we want and we want what we like. It would be strange if things were otherwise. Pleasure tends to make the thing triggering the pleasure desired in the future. A possible basis of this is that opioids released during sexual activity sensitize the dopamine-based wanting system. If we can generalize from male rats to humans, when the consequences of sexual activity include ejaculation, durable changes occur in the brain
’s dopaminergic systems to increase future wanting of sex (Frohmader et al., 2010a). If humans are anything like rats, opioids released within the amygdala act to confer incentive salience on stimuli (Mahler and Berridge, 2012).

  However, research strongly suggests that under some conditions, liking does not mirror wanting exactly (Robinson and Berridge, 1993). The research and evidence have mostly involved feeding and drug-taking, but there are a number of indications that a similar principle applies to sex. Even Peter Trachtenberg (1989, p. 81) reported: ‘Sex no longer gave me anything more than the physical release of ejaculation.’ Although somewhat anecdotal, there are reports that for many people their first experience of intercourse, even of orgasm, was not that great (Levin, 2006). However, this usually does not put them off for life, but rather wanting remains intense. It seems that a process of learning can be involved in forming an association between (a) sexual behaviour and orgasm and (b) pleasure.

  A number of women, who are in long-term relationships report little desire but still enjoy sexual behaviour when it happens (Meana, 2010). The pleasure and arousal do not translate into a desire for more frequent sex. In sex therapy, the desire of the male is often much higher than that of the female. In this situation, men frequently cannot reconcile their partner’s apparent liking of sex with their lack of desire to repeat the experience.