The science behind love at first sight
Scientists are exploring how your brain and body react in the first seconds of attraction.
Rom-coms aren’t lying to you: love at first sight is a real phenomenon. It’s a strong—but not all that common—initial attraction, and it has the potential to grow into an enduring relationship.
But science shows us that it’s not your heart that falls in love fast, it’s your brain. Through neuroscience, behavioral experiments, and psychological research, scientists are mapping how attraction can spark almost instantly. Entire labs at research universities are dedicated to better understanding romantic love, although the speed at which love at first sight happens makes it more difficult to study. Still, researchers have an idea of how our brain reacts—and how we’re actually hardwired to quickly form impressions of people—based on their understandings of the early phases of love.
Here’s what happens in our bodies when we experience love at first sight, and how the chemical reaction can turn into love that lasts.
How falling in love affects your body?
Decades of research suggest that attraction—the passionate beginning phase of a romantic relationship—has its own unique set of chemical cues, including adrenaline and dopamine.
Like that passionate phase, love at first sight is “probably a very emotionally arousing event, and so that would activate the sympathetic nervous system, which is a fight-or-flight response,” says Sandra Langeslag, a biological psychologist at the University of Missouri-St. Louis and a member of the University of North Carolina at Chapel Hill Love Consortium, which is dedicated to the scientific study of human connection.
“Your heart rate goes up, you start to sweat a little bit, you start to breathe faster, maybe you start to blush a little bit. And all of that is to prepare us for action,” she says.
When you’re love-struck, the hypothalamus, a small area tucked deep in the brain, signals for adrenaline to rush through your bloodstream, which is what makes your heart race, Langeslag says.
A foundational study by anthropologist Helen Fisher showed that when we look at people we romantically love—not just find attractive—the reward centers of our brain light up and become more active than usual. That’s indicative of the presence of dopamine, the so-called feel-good hormone. Dopamine creates a pleasurable experience, and can also help create long-lasting memories, which might be why that first sight is so memorable.
(Why dopamine drives you to do hard things—even without a reward.)
Why are we able to fall so fast?
The ability to experience love at first sight rests on a cognitive skill you might not even realize you have: Humans are incredibly good at quickly assessing other people. “In less than seven seconds, we can form impressions that are actually fairly accurate,” says Wendi Gardner, a social psychologist at Northwestern University.
By that, she means “they're accurate in terms of they're likely to be widely shared by other members of our culture.” The human brain can’t really instantly know someone’s character—that takes time. But our brains can rapidly process physical cues in others to form an impression that, right or wrong, is shared by the masses and could make us fall fast, especially if someone is attractive.
Our brains interpret nonverbal signals like symmetry and smiling to form a positive impression of a person. We may not be conscious of it, but our brain is taking it all in and doing quick calculations to determine attractiveness. “We don't even need to hear what they're saying, we just need to see the way they're behaving, signals about their face, physical attractiveness, the way they dress, and their nonverbal signals like eye contact and smiling,” Gardner says.
In short, “we are total suckers for physical attraction,” she says. “People talk about ‘Oh, I don't pay attention to anyone's appearance,’” Gardner says. “You can think that all you want, and I promise that you are wrong…there is no human on Earth who is a visual perceiver who isn't noticing these things.”
But instant love isn’t just for the most physically attractive among us—other types of connection can be foundational for relationships. It’s a psychological idea called I-sharing, but it’s more commonly understood as the moment when strangers “click.” First introduced two decades ago, I-sharing is fleeting belief that you are experiencing the same subjective reality as another person in the moment. This psychological phenomenon builds an instant connection by temporarily erasing feelings of existential loneliness, making us feel understood and increasing affection and trust. Research in the Journal of Social and Personal Relationships shows that it does, and that these shared moments are associated with greater romantic satisfaction.
Gardner also explains it through this example: “If you've ever been to a coffee shop, and something funny happens, whether it's maybe what someone's wearing, or the music, or the way someone laughs, or something that is just charming and endearing,” she says. “And you look up with a little smile, and you see someone else across the coffee shop also is looking up with a smile, and then your eyes meet. That's enough.”
A trivial occurrence can create a lasting, connecting impact by showing us that we may perceive the world the same way as a stranger. That glance not only opens up the opportunity for love at first sight, but it can also lay the foundation for a longer relationship.
Love that lasts
Powerful as love at first sight may feel, the initial attraction alone is not a good indicator—or really, an indicator at all—of if there’s something more. “It has no predictive value. It's great, it feels good, it means nothing,” says Paul Eastwick, a psychologist at UC Davis and author of Bonded by Evolution: The New Science of Love and Connection. “It's a nice experience to fall for somebody right away, but it is neither a bad sign nor a good sign for where this thing is going.”
It’s not the most optimistic reality in a world where hundreds of millions of people use dating apps, and many users rely on quick judgments of attraction to lead to long-term relationship success. “To suggest to people that this is what they should be looking for, I cannot stress enough how people need to be doing the opposite,” Eastwick says. Research shows skipping the small talk and engaging in more meaningful conversations with strangers may be less uncomfortable—and more rewarding—than we anticipate.
So for the love fools among us, give it time and be cautious, “It’s a common experience to find that your impressions are going to change,” Eastwick says. “It’s okay to lean into the uncertainty a bit. You don't know a lot about this new person that you've met.”
