What Science Reveals About the Many Facets of Desire

Falling into the limerent habit
Desire is a curious thing. Some desires are easily satisfied—they pass quickly after they are successfully gratified, and rarely intrude into our consciousness. A lazy afternoon at the beach is a pleasure, but one we only seek occasionally. Other desires are insatiable. For those rewards, the thirst for more persists no matter how much access we get. Even after gratifying such desires, the longing barely fades—or if there is any relief it’s short-lived. Indulgence of such desires can lead to an escalation of the hunger, rather than contented satisfaction. This is not always a negative thing—to give and receive love is an example of a desire we never tire of—but insatiable desires are hard to moderate.

At the worst extreme, some desires can develop into such an irresistible craving that they become the primary focus of life, dominating all other concerns. These are the desires that religions warn us about. People battle to resist temptation, instinctively sensing that they are too seductive, too powerful, too encompassing; too deranging or destructive to be safely managed. Such desires can persist even after the reward itself ceases to be pleasurable.

This is the realm of addiction.

The strength of desire
Limerence certainly falls into this category. Desire for a limerent object is shockingly powerful. Many limerents describe their experience in terms that are usually associated with drug addiction—feeling high, craving supply, suffering withdrawal.

By the time I realized I was in serious trouble my limerence was out of control and it was too late, I was hooked on LO and couldn’t let go. — LA

I look for him and crave the feeling that I get when I see him, even as I know that I don’t want to go back to all the lying and hiding….I know I don’t want him—just the flood of chemicals that he triggers. It can be really discouraging and feel shameful to be this kind of junkie. — J

This isn’t just hyperbole. There is good reason to frame limerence in terms of addiction. The arousal, reward, and bonding systems that produce the ecstatic connection of limerence are also central to the development of addiction. When driven too hard and for too long, these systems adapt and remodel. Reward-seeking becomes unbalanced and difficult to resist. The progression of limerence can be understood as a shift from desiring another person to becoming addicted to them.

If you’ve learned to want something enough, liking it becomes almost irrelevant.

It’s strange that we have a vulnerability like this built into our brains. How does a neural system that evolved to help us seek good things and avoid bad things go haywire and make us want something with harmful intensity? The answer lies in the subtleties and peculiarities of the reward system, and our old friend dopamine. In particular, there are three important concepts that, taken together, explain the strength and persistence of desires: incentive salience, wanting versus liking, and habituation. Broadly—why we notice things, enjoy them and then get bored of them. These factors help explain why limerence can escalate so dramatically from initial attraction into overweening obsession.

Incentive salience
Incentive salience is the phenomenon of noticing things in the environment that we have learned are rewarding, and thereby recognizing them as desirable. It explains why some cues are attention-grabbing—they seem to jump out of the complex background and demand our attention. If you were to walk into an untidy room with litter everywhere, you’d quickly notice if a handful of sparkling gold coins were scattered among the debris, and likely feel an urge to collect them up as a prize. Dopamine is at the heart of this phenomenon, and it causes the stirrings of motivation that begin after we notice something desirable. As it turns out, like good comedy, the influence of dopamine over incentive salience is all in the timing.

Dopamine release is the mechanism by which the brain tracks rewards, and it works by providing a “reward prediction error.” In the simplest case, an unexpected reward (say, discovering some tasty fruit when hungry, or having someone attractive declare their love for you) causes a burst of dopamine release into a part of the basal ganglia known as the striatum—specifically, the nucleus accumbens. This is a part of the brain that registers pleasurable rewards. When we are not anticipating a reward, but receive it as a surprise, dopamine is released in a burst of activity that signals this unexpected outcome. The failure to anticipate reward is the first kind of prediction error.

The next stage of reward prediction depends on the fact that the reward system does not operate in isolation. It is integrated into other brain regions, most notably those that lay down memories (the hippocampus) and interpret outcomes (the prefrontal cortex). When a reward has been experienced enough times, we learn to associate that particular object, person, or set of circumstances with pleasure, and therefore know how and when we can get more. As an example, consider the merits of a good cup of coffee. For those who have learned the association, drinking a cup will give predictable gratification. The aroma of coffee brewing reliably provokes desire.

There is an understandable, foreseeable progression to the behavior that can be predicted from the rules that govern the underlying neural circuits.

For this reward-prediction scenario, there is an interesting and important shift in the timing of dopamine release. Instead of simply registering surprise, the dopamine system begins to take the initiative. It becomes attuned to cues or triggers in the environment that we’ve learned are associated with rewards, and dopamine is released in anticipation of securing the prize. The reason I start desiring coffee in the morning when I arrive at my desk is because my cup is next to the keyboard, the kettle is plugged in beside it, and I habitually start my day with a stimulating hit of caffeine. All these cues are reminders of a source of reward, and that causes the release of dopamine in anticipation of pleasure, which motivates me into taking action.

(To give an impression of how effective this system is, I just stopped writing to brew coffee, as the craving was beginning to nag at me enough to spoil my concentration.)

Dopamine release operates as a motivating impulse. Instead of registering an unexpected reward, dopamine is released to stimulate us to seek reward. Because of the learned association, cues in the environment subconsciously trigger reward-seeking behavior.

If this motivated pursuit results in us successfully securing the reward, a curious thing happens to our dopamine levels: nothing. The burst of dopamine that triggers motivation simply subsides. If the expected reward is secured, then no prediction error has occurred, and no additional dopamine is released.

Alternatively, if the expected reward doesn’t occur—for example if I’ve carelessly brewed my coffee too strong—then there is a change in the reward circuits. The dopamine neurons stop firing. That pause in dopamine release signals a failure in reward arrival, a new kind of prediction error. This final point highlights another important subtlety in the dopamine reward system: it’s always on. The neurons that release dopamine into the striatum are firing at a baseline rate—ticking away constantly to release a regular, low-level supply of dopamine, known as the “tonic” level. Unexpected rewards cause short-lived bursts of release that are superimposed on top of this baseline (the “phasic” dopamine release), whereas failed rewards decrease the tonic rate of firing. In a way, the reward system works a bit like cruise control in a car—it maintains a fixed steady speed (your basic level of motivation), but you can always hit the accelerator or brake to deal with changing conditions.

The reward system therefore operates as a multifunctional mechanism that allows us to detect rewards, learn to anticipate rewards, recognize cues in the environment that are linked to rewards, motivate action to seek the reward, and assess the success of our predictions. Quite clever, really.

Unfortunately, it has a few imperfections.

Wanting versus liking
The first interesting wrinkle that needs to be considered is the fact that dopamine does not directly cause the sensation of pleasure. Dopamine is a relay system that integrates all the sensory inputs that denote reward, and activates the desire to seek more, but it isn’t needed in itself to experience the joyful thrill of bliss.

A recent advance in our understanding of reward-seeking behavior is the fact that wanting and liking are distinct phenomena. Feeling pleasure and wanting pleasure are separate processes at a neurochemical level. The experience of wanting is driven by dopamine. The experience of liking seems to be triggered by different neurotransmitters, most likely endorphins and endocannabinoids (the natural equivalents of heroin and cannabis, respectively).

Within the circuits of the reward system, there are tiny subregions known as “hedonic hotspots” that are central to the sensation of experiencing pleasure. Injecting drugs that mimic the “liking” neurotransmitters into these hotspots can greatly amplify the intensity of pleasure.

The discovery of this phenomenon came from watching mice drink sugar water. Sweetness is intrinsically pleasurable, and it’s possible to measure this objectively from the expression that animals (and people) make when they are enjoying the sensation. From careful research, the details of these neural centers have been pieced together. It’s now becoming clear that the mechanism for experiencing intrinsic pleasure is separate from the reward-seeking systems, which means that wanting something and liking it can become uncoupled. Even with no motivation to seek sugar, you can still experience pleasure from tasting it. Conversely, you can be motivated to seek something that no longer provides intrinsic pleasure

Because you once learned to want it.

This discovery can explain apparently irrational behavior. For example, why a bitter drink like coffee, which should be aversive, can become an acquired taste that is craved as a stimulant. It explains why someone suffering a fearsome hangover could nevertheless want to get drunk again. It explains why some still seek the affection of a partner who was once loving and attentive but has turned moody and distant, or why you continue to crave contact with a limerent object (LO) who is obviously incompatible. If you’ve learned to want something enough, liking it becomes almost irrelevant.

As a further curiosity of “liking,” the distribution and sensitivity of those tiny, hedonic hotspots can be altered by other factors, such as stress, hunger, or pain. That means that you like things less when you’re stressed, but you still want them. In fact—in one of life’s little ironies—you’ll probably want them more than ever, right when they fail to give the hedonic pleasure you’d hoped would bring relief.

Finally, it turns out that many different sources of pleasure all work through the same hotspots. So, chocolate, orgasms, limerence, and heroin may all depend on the same little bundles of cells to evoke their fundamental sensation of pleasure. Our higher centers in the cortex make sense of the different contexts and meanings of the pleasures, but liking has a simple, fundamental basis in the brain.

Dopamine makes us want things, independently of whether we still like them, but what makes that desire for reward fade away? What makes “wanting” stop?

Habituation, or why desire fades
In terms of neuroscience, the fading of reward is known as “habituation.” It’s a fundamental feature of neurophysiology, and describes the phenomenon where repeated exposure to a stimulus (either good or bad) leads to a diminished response over time. You get used to things that happen repeatedly. This process allows you to stop wanting things that are easily obtained and stop fearing things that are easily avoided.

If you repeatedly listen to a song that you really like, you’ll tire of it. If you eat your favorite meal every day, you’ll lose your appetite for it. If you constantly consume erotica, you’ll become jaded. Habituation is the mechanism through which exposure to rewards leads to fading pleasure, but the devil is in the details, again. There are some subtleties to the mechanism that can explain the unpredictability of loss of desire.

The process of learning to suppress a response to the rewarding stimulus happens at the level of the reward system—there is a decrease in the size of the dopamine release caused by a particular reward cue once the circuit has become habituated. Habituation is most effective when the rewarding stimulus is weak, encountered frequently, and can be predictably secured. People who own orchards rarely crave apples. In contrast, some stimuli are incredibly powerful, hard to find, and unpredictable. Finding a romantic partner is a high-stakes, low-odds endeavor that many people pursue with single-minded determination.

The habituation process isn’t always smooth and straightforward. A long period of foregoing a pleasure can result in the desire returning—you effectively forget that you had grown tired of the reward. Similarly, encountering a stimulus in a new or different context can reignite old desires. Finally, some stimuli are stubborn to habituate and undergo a period of increased desire in the early phase of experiencing them—a process known as sensitization.

That means a taste of bliss leads to increasingly urgent reward-seeking that grows in intensity before you ever begin to develop a resistance to its charms.

Putting this all together, habituation teaches us that you don’t ever really stop wanting something, it’s more that you learn you don’t need to want it anymore. The brain actively, but provisionally, suppresses the reward systems while in a time of plenty. It’s pretty obvious that this is a fairly fragile mechanism for suppressing desire. The scope for relapse is high.

How habits form
These neurochemical details of how reward and pleasure work in the brain might seem like an academic diversion—an intellectual rabbit hole—but they have real-world implications for understanding the apparently irrational behavior of people who have been driven into a state of compulsive, single-minded desire. There is an understandable, foreseeable progression to the behavior that can be predicted from the rules that govern the underlying neural circuits.

When someone encounters an extremely pleasurable reward for the first time, both the dopamine reward and endorphin “liking” systems will be maxed out. This could be the euphoric bliss of an orgasm, a hit of heroin, the thrill of skydiving, a big win for a gambler, or that romantically potent lingering eye-contact with a new limerent object. Such an experience would be memorable and inflame an intense desire. Inevitably, we will want more.

The early phase of reward learning then begins, where the source of pleasure is sought, experimented with and refined until we feel it’s understood—how and when the reward can be secured, what cues are linked to it, and what particular behavior enhances or reduces the chance of reward. We test the boundaries and parameters until we are confident about how to get access to the pleasure again. Then we keep doing it, each time reinforcing this reward-learning mechanism.

Once these associations are learned, dopamine motivates us to repeatedly carry out the behavior that works. This is when environmental cues that remind us of the reward trigger the impulse to seek it. Importantly, once this associative learning process has set in, it becomes largely unconscious. We act before we are even aware of what’s happening. It isn’t that we spot a cue, think about its significance, decide what the best response should be, and then make a purposeful choice—instead, we spot a cue and our brainstem dumps dopamine into the striatum to impel us into action, faster than our thoughts can catch up.

While seeking a limerent object is a good case study in unconscious motivation, perhaps the best modern example of this phenomenon in practice is the cell phone. We’ve all learned that the little black rectangle in our pocket is an almost limitless source of stimulation—an infinity pool that can be relied on for a rewarding boost of entertainment and distraction when we’re bored or uncomfortable. It’s often in our hands and lighting up before we’re consciously aware of having summoned it. The web browser icon on my desktop is the same—I’ve often launched it before I’ve given any thought to what I was intending to look up. I’ve just learned, at a very deep, subconscious level that there’s good stuff on the other end of that click.

The momentary confusion you feel when you find yourself looking at a screen that you didn’t consciously, actively choose to engage with, is a good sign that your “executive brain” has been sidestepped by subcortical associative learning. The reward-seeking behavior has transcended active intent. It has become a habit, and habitual behavior can be very hard to unlearn. Once it’s established, a habitual program basically runs on automatic.

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