top of page

Intimacy and Habituation: We Need to Talk

One of the problems with exploring the neuroscience behind any kind of human experience is the fear that doing so is reductive, and turns the experience into “nothing but” the underlying biology. As I have tried to make clear, and it is a lesson worth many repetitions, that just because the biology is necessary for an experience doesn’t make it sufficient. That does not mean that functions can “float free” of the biology necessary to accomplish them, any more than the bounce of the ball can float free of the ball when it is deflated. Obviously, bouncing requires more than just a ball, but a ball in certain circumstances, initiated by certain actions. So too does a “throw” not float free of the hand doing the throwing, but it also requires something being thrown. The victory of Aristotle over the dualism of Platonic Forms.

Similarly, not listening to bad news doesn’t mean it isn’t occurring, and pretending one didn’t do something doesn’t mean one isn’t responsible for its consequences. But worse, refusing to learn about something because one doesn’t want to think about it doesn’t mean that doing so might not actually be useful, informative, or even helpful to understand and function under its constraints. “Constraints” are sometimes what makes it possible for something to happen. Being unable to bend your lower leg forward at the knee is not only important for human locomotion, but locking the knee may be important to upright stance

Hence, there are a range of basic facts about human biology, and the physiology of our cognitive and emotional lives, our heads and our hearts, that appear, on first pass, to be bad news. Positive emotions like interest or joy, for example, tend to have lesser intensity than negative emotions like anger and fear, given the sympathetic physiology of fight and flight. As one might expect, since oxytocin feeds the neurochemistry of attachment, it is also important to the attachment and caregiving between parents and child. But wait, that makes sense evolutionarily, as the former are energizing us for immediate threats, the positive emotions bring us back faster, and can also give us some perspective; plus the added bonus of the intensity of the latter emotions are increased when preceded by the former, which lend their intensity to the even happier ending. What about the “top down” effects, inhibiting all those hot emotional feelings and intensities? But that is what “engaging our brains” is all about, despite those wonderfully addictive feelings. It is about calming down and focusing rather than feeling intense but acting stupid. Sadder, maybe, but wiser may feel better in the long run. Ask the Stoics. What about male “armor” and female “boundary control”? But aren’t these consistent with getting the job done, on the one hand, and being cautious on the other? What about the male shame about money, the female about not being pretty enough? I didn’t say we didn’t have some things we could work on. That “aggression” may be “natural” doesn’t mean it is good, especially at its more violent extremes, but we work on this all the time.

For my money (oops, I’m male, sorry for the metaphor), one of the worst is habituation, feeling less and less with repetition of the same stimulation over time. We’re wired to respond to change. Obviously this makes sense in our “environment of evolutionary adaptedness,” where things that are unchanged are the things we don’t need to do anything about (why you never throw out old wardrobe items you haven’t worn for years, or books on a shelf you either have never read, of haven’t re-read for decades. Space is, after all, finite). But it’s also why we hear about and attend to trivial “News” but not the “Olds” that still continue to do damage whether by gradual erosion, or by pushing us closer and closer to a precipice which we don’t see. It’s also why you don’t hear the refrigerator until it turns off, or don’t feel your rear end on the seat until something draws your attention to it. And we do love surprises, at least the ones where we get more than we thought, or things aren’t as bad as they seemed. But yes, as Hamlet said, consciousness does make cowards of us all, though the “native hue of resolution” which is “sicklied o’er with the pale cast of thought,” might well lead to a “native hue” of consequences we’d really best avoid, and caution the better part of valor. Yes, Hamlet did say “conscience” not “consciousness,” but our habituation can be overcome by our capacity for attention, and attention can not only be drawn by survival-relevant events and powerful emotion, but also by our cortical capacities, which include drawing our attention to things because of something we have been taught by others or figured out for ourselves. Because we really can “engage brain” on purpose, because doing so may give us perspective, or advantage we otherwise would not have. Since habituation is really the enemy of arousal, we may have to get down and dirty to stay turned on.

Standard (if apocryphal) therapists’ humor is “If sex isn’t dirty, you are probably not doing it right.” Now, I can understand that this might be offensive to the innocent sexuality of two young lovers exploring their sexuality early on. But even there, I remember one newly non-virgin insisting that there be a kleenex box of “icky wipes” next to the bed of love. For the more jaded, or the married victims of the two-year half-life of romantic love, there may be a different story that needs to be told. For one thing, as Robin Williams once said, you only have enough blood to run one organ at a time. The neural substrate for sex operates well below the level of the cognitive prowess of the frontal cortex, and can become increasingly urgent regardless of whether we think it would be a good idea. For more rapidly arousing ("testosterone poisoned”) men, responding more intensely to more readily available visual information, like that .7 waist-to-hip ratio, this urgency is going to be a steeper and faster fall. For women, a closeness sense like olfaction is a bigger turn-on, and social evaluation, memory, and attention are more important. Romance novels are for women what porn often is for men; the latter also fall in love more precipitously, as there is less at biological stake. There are, of course, “off” switches. Fear and anxiety are going to produce difficulties for the sexual tuning of relaxed foreplay, the comfortable caresses that make for the playful aspects of intimacy, and disgust classically inhibits a whole range of “approach” responses. Let’s not forget that as mammals, male and female humans are amongst the most similar, include the rarity of having male involvement in child-rearing, and are the species for which kindness is more important than either looks or financial success for both genders. Still, men do have more of the neurochemicals of lust and lower levels of those that feed attachment than do women. Hence the classic tension in love between men and women. So slow down, let’s cuddle a while

According to Affective Neuroscience, for those “in love,” the same circuitry lights up in brain scans as when people are on cocaine or opiates. Unfortunately, for men, none of this circuitry does much during sexual arousal per se, though nearby areas do. Much of the subcortical, limbic systems wiring for libido are the same for men and women, but while testosterone may feed lust in women, for men, testosterone is the jet fuel of both sexual arousal and aggressiveness in men, producing a different set of difficulties. As you might expect, dopamine, which also feeds various addictions, also rises during sexual arousal, and is higher when the sex drive and frequency of intercourse are higher. But remember that this is the chemistry of anticipation, not consummation. For men, the hormonal hunger is also tied to arginine and vasopressin (AVP), for which they have more receptors, which floods them at puberty, and which rises with closeness to ejaculation, rapidly declining with orgasm. For women the “bonding” chemical oxytocin is more pervasive, but the concentrations increase for both men and women before lovemaking, and increase after orgasm, especially during the male refractory period, and during the afterplay that builds loving attachment.

There is a tension between attachment and sex, as feelings of insecurity or fears of abandonment can produce anxiety which can be an “off switch” for sex, and even inhibit affectionate caring. Yes, there are gender differences, but like all gender differences they are relative rather than absolute, and they are smaller in humans than other mammals. We already mentioned the different balances in men and women and, as you might expect, there are other roles for oxytocin. Synthetic oxytocin, pitocin, the “obstetrician’s whip,” can be used to induce labor. Much of the pleasure women experience in breast feeding is produced by the oxytocin released by nipple stimulation. In her book, Mother Nature, Sarah Blaffer Hrdy suggests an interesting connection between the practice in pre-revolutionary France of using “wet-nurses” to feed babies, and how a decrease in mother-infant attachment might have contributed to the subsequent generational change. My wife tells me that in pygmy tribes infants’ nipples are often stimulated to help calm them down. Men have nipples, too. So, ladies, what might be the consequence of their stimulation?

Too great of interdependence within a couple can be suffocating. If you know everything someone is going to do, you may stop even being aware that they are doing it. I have talked in my blog about breaking up, that the absence of feeling might just be because you have habituated, producing the couples that only become painfully aware of their interdependence when it ends. We all need some space, as no specific other can do everything for us, and there is a balance between solitude and intimacy, so there is something to share in intimacy. I once co-authored a study with a student where we found that greater experienced closeness was actually associated with some level of attitudinal difference, as long as the “meta-attitudes” about their relative importance were well-attuned. You can’t have healthy arguments about your differences if they aren’t important to you. You need time apart, and you may need the frisson of difference.

The real problem is that the ideal of marrying, for something that has a half-life of two years, and then expecting it to last a lifetime is probably not going to work very well. The surprises of something being more than you expected cannot last. The college where I taught once experimented with “exceeding expectations” as an admissions motto, but that is a hard one to sustain, and I regularly told candidates that if we met the expectations they had in secondary school, we had probably failed them, as part of our goal was to help foster hopes and expectations which they could not previously have imagined. That can also happen in close relationships, as long as people keep changing and growing, but I think, on average, that expectations violated after the first several uncritical “love is blind” years tend to be more disappointing than happily surprising, and that surprises tend to come less and less often. Familiarity may not breed contempt, but it hardly sustains desire, especially when a partner becomes a “sure thing.” I suspect that this is a big part of the “Westermarck Effect,” that people living in close proximity for the early years of their lives tend to be sexually desensitized, so that arranged “child marriages” which involve living together for years, are difficult to consummate and often have no issue. But I’m sure it is also behind what happens in genuinely coed housing (alternate rooms vs separate wings) in college dormitories where men and women tend to support each other in healthy ways (including reducing the likelihood of harassment and abuse), that their (only slightly) greater likelihood of sexual activity tends not to be with each other, since they have become like brothers and sisters. Interestingly, in the research of Jonathan Haidt on moral disgust, part of a larger research program on how the rational cart gets led by the emotional horse, he asks subjects to judge fictional scenarios in which normal rational objections have been eliminated, and finds that it is only the subjects with opposite sex siblings that continue to feel disgust. Maybe the historically common practice of husbands and wives having separate beds or even separate bedrooms produces a kind of “Westermarck Attenuation Effect.”

Dolf Zillman’s suggestion that coition be added to fight and flight as a third variety of sympathetic hyperactivity may help understand some alternatives to the habituation to sexual stimuli with high familiarity. Fight/Fight/Coition covers three of the “Four F’s” of mammalian motivation controlled by the hypothalamus: Feeding, Fighting, Fleeing, and Reproductive Behavior ;-). First, despite including some parasympathetically controlled components (e.g. “genital vasodilation” -- if that doesn’t stand out, think erection), sexual arousal includes sympathetic dominance of the autonomic system, a preparation for vigorous action with the energy for just one episode. Second, all three states include awareness of both causal circumstances and goal responses. Third, while sexual arousal may not qualify as a coping emotion, it is adaptive, not to the preservation of the self, but of the species. The practical implications have to do with the interdependencies produced by the sympathetic commonality. That is that preceding and concurrent arousing events that are not sexual can nevertheless alter precoital and coital behavior and its experienced quality.

There are close brain proximities. Electrically stimulating near areas that control erection in male nonhuman primates produces fight/flight responses, and vice versa. Directly stimulating fight/flight areas eventually produces sexual excitement. The reverse is also true. Excitation of the amygdala, controlling fight/flight, spills over to septal control of sexual behavior, and vice versa. Fight, flight, and coition are emotionally primary. With the “neural spillage” they function as a unit.

The autonomic connections are actually a little more complicated. Fight, flight, and coition are all served by sympathetic outflow from T12 and L1, the last thoracic and first lumbar nerves (the middle of the back), which prompt the release of epinephrine and norepinephrine from the adrenal medullae. This also reaches the sexual organs, producing what is called the psychogenic sexual center, i.e. the one responding to distal (visual and auditory) sexual stimuli, which produces both sympathetic excitation and genital tumescence (not just limited to men). There is a second reflexogenic center, of parasympathetic outflow from S1 and S2, the first two sacral nerves, which produces “sexual reflexes” including, you guessed it, “genital vasocongestion.” But which also have some control over micturition and defecation (like peeing yourself in excitement or being literally “scared shitless”). Research from those with spinal cord damage shows that the psychogenic and reflexogenic centers can function rather autonomously, so a paraplegic person can still reach tumescence with appropriate tactile stimulation, without much sympathetic arousal, and distal sympathetic arousal can be produced despite lessened tumescence. Don’t you love the big words? Do you know how Garp (played by Robin Williams in the film version) got his name in John Irving’s The World According to Garp? For those of us without spinal damage, these centers operate synergistically. Just in case you missed the bit of good news here: Reflexes don’t habituate!

bottom of page