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The brain circuitry of love is interesting and complex. It can involve every part of the brain, including regions that control your hormones and the blood pumping from your heart. Scientists have studied varied aspects of this emotion but there’s always more to learn. For this Valentine’s Day we’re thinking about the role our senses play in love.

Sight

William Shakespeare once called the eyes the windows to the soul, but can we really tell what’s going on in the mind of another person by looking into their eyes?

Well, we know that we can tell a true smile from a fake by the crinkling around the eyes, and we can learn about someone’s mood from their brow -- worried or excited look very different -- but we can learn the most from the size of the pupils. Pupils are literally holes in the eyes that adjust to let in more or less light. When we’re paying particular attention to something, maybe because we’re really attracted to it, our pupils dilate to allow us to see more clearly.

Several studies have shown that prolonged eye contact can both indicate your interest in someone and determine if they are interested in you. Other studies have even shown that prolonged staring into each other’s eyes will increase feelings of love.

Taste

Our taste receptors are a critical part of determining when something is dangerous or pleasurable. Throughout human history, our taste receptors have helped us identify nutritional foods and avoid poisons and toxins. We are attracted to sweet and salty flavors, as well as savory ones, while sour and bitter flavors tend to be aversive in high quantities (which is why we add sweeteners to lemons, coffee, alcohol, and so on).

In a 2015 study, researchers found that participants who ate sweet candies prior to speed dating were more likely to report romantic interest in those they met. Maybe taking sweets to your sweetie has some science to back it up!

In other tasting science, have you ever wondered why exactly we kiss? Scientists aren’t actually sure, but there’s some evidence that kissing is actually a method of taste testing your partner. It seems to serve as a mate-assessment tool. Biologists have known for a while that we share a lot of information about our immune systems when we kiss, and in 2014 a research team found that as much as 80 million bacteria are swapped between a couple in 10 seconds of kissing, transforming each others’ microbiomes.

Sweet and salty flavors will elicit a neurochemical cascade of pleasure, whether that’s from a box of chocolates or from the taste of sweet kisses.

Touch

Touch can be persuasive. In a 2007 study, researchers found that when a man touched a woman’s arm lightly while asking her to dance, she was more likely to say yes. A 2011 study found that touch increases the brain’s response to emotional situations, improving empathy and connection.

Brain imaging studies have found regions of the brain that react specifically to romantic partners. And what’s more: touching a romantic partner can be more than pleasurable, it can actually reduce your stress. Studies have shown that hugging or holding hands with a romantic partner can lower blood pressure and heart rate, particularly before a stressful event like public speaking.

Sound

Have you ever noticed that you modify your voice in different situations? A study from 2014 showed that men’s voices varied more in pitch and went lower when speaking to someone they found attractive. Another study on voices found that people with more attractive voices had more romantic partners.

The sounds of love aren’t just in voices. Music can be essential to romance. Throughout history, lovers have used romantic melodies and lyrics to convey their emotions to each other. Whether it is composing symphonies or sharing mixtapes or spotify selections, when we share our musical interests we are attempting to put words and sounds to the emotions we’re feeling and impart those feelings into another person’s brain.

Many of us find that background music helps us focus on certain tasks, and that can be true when you’re spending time with your partner or date. Music can help cover odd noises (and awkward silences) that might distract you. When your mind is wandering, music can grab just enough of your attention to keep you from focusing on all the little things and let you zero in on just one big thing. The kinds of music that work best for background music are very individual, however, and what can be soothing for one person can be distracting for others, so if you’ve made a Valentine’s Day playlist, make sure your music isn’t ruining the mood for that special someone you’re spending time with.

Check out this neuroscience love song to learn more about love musically!

Smell

Our sense of smell is one of our most powerful senses and it is totally underrated. While taste can tell the difference between sweet and salty, it is our olfactory system that gives the thousands of variations on a theme.

So who smells good to us, and why? There are a group of studies that looked at how people respond to the scents of potential partners by smelling their dirty t-shirts. Several of these kinds of studies have shown that women prefer men whose immune systems genetically differ from their own, which in theory is evolutionarily beneficial for their children.

While the exact mechanisms of pheromone processing in the human brain are a little controversial, several studies have shown that men and women detect testosterone and estrogen in samples provided from other participants, and they show a physical reaction to them. While our social etiquettes of shaking hands and giving hugs seem more civilized than the way our pets sniff each other, we are still exchanging information through smells.

So there you have it: the five senses of love! Use this newly acquired scientific information to have a happy Valentine’s Day.