Love is many things: butterflies and giggles, happiness and comfort, commitment and best friendship.
But love, alas, is not easy to find.
How and why do two people click? We dug into years of psychological research to find some answers. And in the process, we busted some myths and learned that certain clichés turn out to be actually true.
This is an update of an article written by Drake Baer for Tech Insider.
If you care about the environment
It's easy being green -- but only if you're seeking something serious.
A 2016 study found that men and women who make eco-friendly purchases are perceived as more desirable for long-term relationships, while those who make luxury purchases are perceived as more physically attractive and more desirable for short-term relationships.
If you play hard to get
A 2014 study found that men in a speed-dating experiment wanted a woman more when she played hard-to-get by acting disinterested in the men's questions. But these findings only applied in certain situations.
Specifically, the men had to feel 'committed' to the woman, which in this study meant that they'd chosen her as their partner, instead of being assigned to her.
It's also worth noting that, even though the men wanted the woman more when she played hard to get, they liked her less. Alas, love is complicated.
If you display the right facial expression
Happiness is generally attractive on women -- but not so much on men.
In 2011, researchers conducted experiments on more than 1,000 people, showing them photographs of members of the opposite sex and asking them how attractive the people in the photos were.
Results showed that men rated women most attractive when they looked happy and least attractive when they displayed pride. Women, on the other hand, rated men most attractive when they displayed pride and least attractive when they looked happy.
Interestingly, shame was pretty attractive in both men and women.
If you look similar enough to their current or last partner
We may all have a 'type' -- but women are more likely to adhere to it than men are.
In one 2011 study, researchers found that both men and women rated opposite-sex faces more attractive when they closely resembled their current or most recent partners. Men, however, were less attracted to faces that looked similar to their current partner than women were.
If you use a lot of hand gestures
Looking for love? Put yourself out there.
Literally -- fill up the physical space around you with hand gestures and an expansive posture. In one 2016 study, researchers observed men and women in speed-dating sessions. Results showed that people were twice as likely to say that they wanted to see their partners again when those partners moved their hands and arms, compared to when their partners sat still.
For the same study, researchers set up profiles for men and women on a GPS-based dating app, showing them in both expansive and contractive postures. Sure enough, people were selected more often when they were pictured in expansive postures.
If you're really, really similar to them
Decades of studies have shown that the cliché that 'opposites attract' is totally off.
'Partners who are similar in broad dispositions, like personality, are more likely to feel the same way in their day-to-day lives,' said Gian Gonzaga, lead author of a study of couples who met on eHarmony. 'This may make it easier for partners to understand each other.'
If you stare into each other's eyes for two minutes
University of Massachusetts psychologist Joan Kellerman asked 72 unacquainted undergrads to pair off and stare into each other's eyes for two minutes.
'They later reported they had increased feelings of passionate love and affection towards the other person,' Scientific American reports. 'This suggests that long periods of eye contact can connect you to someone and even ignite feelings of love inside you for that person you have never previously met.'
If you respond to their 'bids' for attention and they do the same for you
Starting -- and growing -- a relationship seems to largely depend on how people attend to one another.
Over 40 years of studying couples, psychologist John Gottman says it's a matter of 'bids.' For example, if a bird-loving wife points out to her husband that a goldfinch just flew landed in a nearby tree, he can 'turn away' from her by dismissing the remark or 'turn toward' her by sharing her enthusiasm.
As Emily Esfahani Smith reported in the Atlantic, the results of the 'bids' are staggering: in one of Gottman's studies of marriage, couples who divorced after six years had the 'turn toward' reply 33% of the time, and the couples that were still together had the 'turn toward' 87% of the time.
If you smell right
A University of Southern California study of women who were ovulating suggested that some prefer the smell of t-shirts worn by men with high levels of testosterone.
This matched with other hormone-based instincts: Some women also preferred men with a strong jaw line when they were ovulating.
If you look like their opposite-sex parent
University of St. Andrews psychologist David Perrett and his colleagues found that some people are attracted to folks with the same hair and eye colour of their opposite-sex parents, as well as the age range they saw at birth.
'We found that women born to 'old' parents (over 30) were less impressed by youth, and more attracted to age cues in male faces than women with 'young' parents (under 30),' the authors wrote. 'For men, preferences for female faces were influenced by their mother's age and not their father's age, but only for long-term relationships.'
If you take care of a dog
In a 2014 experiment, 100 Israeli women read vignettes about men.
Whenever the story featured a man who owned a dog, women rated that man as a more suitable long-term partner than a cad who didn't own a dog.
The researchers concluded that owning a pet signals that you're nurturing and capable of making long-term commitments. It can also help you appear more relaxed, approachable, and happy.
Not into pet ownership? The good news is simply being seen with a dog can make you seem more dateable. In one 2008 study, a 20-year-old man approached hundreds of women and asked for their phone numbers. When he had a dog with him, he was much more likely to score their digits.
If you are equally or less good-looking compared to them
In a 1996 study, each participant was rated on physical attractiveness and then randomly assigned to date another participant. Then, participants were asked to rate their satisfaction with their dates. The participants who were more attractive were harsher in their judgments -- even if they were both equally attractive. The better looking someone was, the less satisfied they were likely to be.
But this only applies to the really attractive people. For the rest of us, according to the matching hypothesis, we are more likely to love those who are equally as attractive as we are.
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