Some time ago, I found myself single again (shock, horror!) and decided to get back into the world of dating. One thing that struck me very early on in my forays was that everyone had an opinion about “what worked” in terms of dating. But too often those opinions were based on anecdotes, assumptions about human behaviour I knew to be wrong, or – worse – pure misogyny.

As a psychologist who has studied attraction, I felt certain that science could offer a better understanding of romantic attraction than all the self-help experts, pick-up artists and agony aunts in the world. And so I began researching the science of how we form relationships.

One thing I learned very quickly was that there are no “laws of attraction”, no guarantees of success in dating, no foolproof methods or strategies for getting someone to date you. Human psychology is too complex to reduce to rules or laws of attraction – but that’s not the same as saying that there’s nothing to be gained from understanding the processes involved in attraction. Understanding the science of attraction can’t guarantee you a date tonight, but it can point the way towards forming mutually benefiting relationships with other people.

Location, location

So what does this science of attraction tell us? Well, first, it turns out that one of the strongest predictors of whether any two people will form a relationship is sheer physical proximity. About a half of romantic relationships are formed between people who live relatively near each other and the greater the geographical distance between two people, the less likely they are to get together.

Of course, online dating and dating apps have changed where we meet our future partners. While most 20th-century couplings were either formed in workplaces and colleges or through friends and families, online dating sites and dating apps are fast becoming the most common way of meeting partners and now account for about 20% of heterosexual couplings and more than two-thirds of same-sex couplings in the US. But even online, geography continues to have an influence. After all, the point of online dating is eventually to meet someone offline – and it costs more time and money to meet someone who lives further away. Proximity matters because it increases the chances people will interact and come to feel part of the same “social unit”.

Second, appearance does matter. People perceived to be physically attractive get asked out on dates more often and receive more messages on online dating sites. They even have sex more often and, apparently, have more orgasms during sex. But physical attractiveness matters most in the absence of social interaction. Once social interaction takes place, other traits come into their own. It turns out that both women and men value traits such as kindness, warmth, a good sense of humour, and understanding in a potential partner – in other words, we prefer people we perceive as nice. Being nice can even make a person seem more physically attractive.

Love is blind

But of course, the social context matters as well. Consuming alcohol, for example, really can make everyone else appear more physically attractive. And my own research has shown that love sometimes really is blind. People in romantic relationships, particularly new relationships, are biased in how they perceive their partners. They view their partners as more attractive than objective reality – something I’ve called the “love-is-blind bias”.

Third, it seems that we like people who like us. This idea of reciprocity may sound very simple, but it has incredibly important implications for all relationships. Chat-up lines may sound like a bit of fun, but all romantic relationships are built on reciprocal self-disclosure – the mutual exchange of intimate information with a partner. Deciding when and how to disclose intimate information to a new partner is an important part of every romantic relationship and can be the difference between an honest, healthy relationship or a closed, stunted one. Also, playing hard-to-get almost never works. Giving the impression of dislike is unlikely to spark attraction because it goes against the grain of reciprocity.

We like what we know

Finally, despite what many people think, opposites very rarely attract. In fact, decades of research has shown that attraction is most likely to be sparked when two people perceive themselves as being very similar to each other. But similar how? It could be similarity in terms of sociodemographics – most relationships are formed between people who are similar in terms of age, social class, occupational background, and so on. But more important than sociodemographics is similarity of values – everything from musical tastes to political orientation. We’re all motivated to think that our views of the world are right and when someone disagrees with us, we feel uncomfortable in their presence. But when someone agrees with us, they validate our worldviews and as result we want continuing contact with that person.

Knowing all this, is it possible to predict with any accuracy whether two people will form a stable relationship? Probably not. One the difficulties with these sorts of predictions is that relationships are complex and often messy. For a start, relationships are stressful and stress can sometimes make us behave in strange ways. And we bring all bring “baggage” into new relationships, whether it’s preconceived notions of what a relationship should be like or our past experiences with previous partners. All of this makes it difficult to know in advance how relationships will turn out in advance. But that’s also what makes the science of relationships so fascinating.