Love Flicks Your Brain’s Commitment Switch

Photo by Evan Kirby on Unsplash
Love is a smoke raised with the fume of sighs
— William Shakespeare

Romantic love is a powerful social force, but you don’t need me to tell you that. Many of our most dramatic memories are likely to come from interactions with people we adore. When we profess our love but the feeling isn’t reciprocated, it can leave us feeling lonely, embarrassed, and even depressed. When love is requited, it is almost the mirror image: elation, motivation, and boosted self-worth. These experiences have inspired some of the greatest literature and most popular entertainment in history, from Shakespearean tragedies to Witherspoonian romantic comedies. How do we fall in love in the first place, and why is it so breathtaking?

Let’s start in the brain. Are there any patterns of brain activity that predict whether we will like someone when we meet them? Researchers tested this question by putting participants in a brain scanner and analyzing their brain activity while they looked at photographs of prospective romantic partners. After the brain scanning, participants actually got to meet the people from the photographs at a speed-dating event. This gave the researchers a great opportunity to examine whether the brain activity they measured in response to the photographs predicted decision-making during dating.

The researchers identified two areas of the brain that were active while participants weighed up the photos, and that predicted their later choices. The first was the paracingulate cortex — an area on the medial surface of the brain — which coded for judgments of physical attractiveness. Beauty judgments were fairly consistent across participants. The second relevant brain area was the rostromedial prefrontal cortex — another more frontal medial area — which instead coded for judgments about perceived personality and likability, preferences that varied between participants.

The medial frontal surface of our brain therefore computes several bits of information about people who could become future romantic partners, including general information that we all tend to agree on, and information that is more specific to our personal preferences. Love at first sight may depend on the levels of activity in your paracingulate and rostromedial frontal cortices.

We understand some of what the brain is doing when we look at prospective partners, but what exactly is it that makes two people compatible and successful in building a relationship? A few obvious possibilities may spring to mind — a similar sense of humor, shared experiences, matching personalities, etc. But the answer is a lot more difficult than you might expect, because these variables are not great at predicting relationship outcomes.

In 2017, researchers tried to uncover what makes a couple compatible, but learned that it is incredibly difficult to predict romantic desire based on personal attributes before two people meet. The researchers assessed over 100 traits and characteristics for a group of undergraduate students who would then attend a speed-dating event where they would interact with around 12 people. Although the traits could predict people’s general tendency to romantically desire other people, and to be desired by other people, they could not predict relationship outcomes for a specific couple. Your personality and attitudes may explain why people generally find you attractive, but they won’t explain why you’re particularly compatible with your current romantic partner.

After we’ve dated someone a few times, we face the prospect of falling in love with them. As intense romantic love develops over the first couple of months and years of a relationship, the brain shows some specific patterns of activation. When we look at a photo of our recently established romantic partner, reward and motivation areas of the brain boost their firing. Those areas include the ventral tegmental area and caudate nucleus, which are typically involved in releasing and utilizing the neurotransmitter dopamine, an important chemical within the brain’s reward systems.

Love is essentially a motivation function and differs from the feeling of sexual arousal; the neural networks underlying love and sex overlap to some degree, but they are also distinct in important ways. Our sex drive pushes us to look for new mates, while our love drive encourages us to stick with a specific partner and take care of important responsibilities like raising children.

The activity in some of these early-stage love areas of the brain can actually predict long-term relationship outcomes. One group of researchers contacted their participants from a previous experiment on budding relationships, and asked them to return to the lab 40 months later. Half of them were still with their previous partners while the other half had separated. The researchers found that the people who showed more activation in their caudate nucleus during the early experiment were more likely to remain with their partners 40 months later and more likely to report greater relationship commitment. They found the opposite pattern in a brain structure called the nucleus accumbens: deactivation was associated with better relationship outcomes. Low nucleus accumbens activity in the presence of temptation has previously been linked to better self-control, suggesting that perhaps those with a better ability to control their impulses are more likely to remain in committed relationships over the long term.

Long-term love has some additional components in the brain. It recruits some of the same dopaminergic areas stimulated by early romantic love, but it also recruits areas involved in maternal love such as the globus pallidus and substantia nigra, which are structures packed with oxytocin hormone receptors. So, in a sense, we view our spouse as a disturbing mix of parent and lover. Oxytocin is a hormone that facilitates social bonding in humans and other species, helping us to strengthen attachments with family and romantic partners. Among early lovers, particular variants of an oxytocin receptor gene, specifically variants that are associated with social disturbances, can predict poor empathic communication. Many of us have probably experienced firsthand how a lack of empathy can be harmful to a relationship.


Love is anterior to life, 
Posterior to death, 
Initial of creation, and 
The exponent of breath.
— Emily Dickinson

We need love to be truly happy, and the online dating revolution has opened up a whole new world of opportunities for meeting prospective romantic partners. This increased opportunity is a blessing for many, especially those who have typically struggled to meet new people. But it may be worth keeping an eye on the possible costs too. Online interactions with strangers lack many of the rich social signals and qualities associated with meeting people in person. During the first interaction, we can’t look into their eyes and assess them based on the subtle way they physically speak or act in front of us. By looking at a static idealized photo as the first point of contact, we throw out all those years of evolution that fine-tuned us for rejecting unpleasant people and attracting us toward compatible people.

In essence, we may be swiping away the love of our life and arranging dates with people who would never have passed our initial sensory checks in the physical world. We may also be shifting our priorities toward a shallower mindset that isn’t necessarily suited to building the healthiest long-term relationships. In the traditional face-to-face social world, the person we swiped away in an app might have had a second chance to impress us with their other behavioral qualities. To be clear, I don’t consider myself a dating app skeptic; I’m actually an optimist but also a worrier who tries to look at both sides of every coin.

Love will continue to be the biggest priority in our life, whether it’s toward our families, partners, or children. It gives us a reason to live and motivates us to be a good person that people want to associate with. Although unreciprocated love can make us feel as though we never want to love again, our persistence in finding the right person pushes us into environments that develop and enhance our character. As we move closer to finding our lifetime companion, we become better people, and ultimately tie ourselves to a wonderful person who is willing to accept our remaining flaws.