Have you ever fallen for someone? I bet I can tell you what drew you to them in the first place. Social psychologists who study interpersonal attraction will often refer to three main environmental factors that start hatching those little stomach butterflies. Those are familiarity, proximity and similarity. But often left out of this little threesome is the concept of complementarity.
First, let’s bring you up to speed
The familiarity principle (a.k.a. the mere exposure effect) refers to the fact that the more frequently you are exposed to a person, the more attractive they become. We don’t like strangers at a visceral level, so the more contact we have, the less we’re influenced by our instinctive distrust. Makes sense, right?
The proximity principle (a.k.a. the propinquity effect) is even more straight-forward. It’s not even particularly psychological, more like economical. Basically, you’re more likely to hang out and hook up with people that are geographically closer to you. The more you encounter them, the more likely you are to incorporate them into your social circle.
The similarity principle (a.k.a. the matching hypothesis) is a tad more complex than the others. It refers to the idea that people tend to be more attracted to others when they are matched. For example, matched in terms of their appearance (although looks are only the third most important attribute when it comes to attraction), social status, ethnicity, and so on. The more points at which they match, the more attracted to one another they tend to be. Now usually similarity refers to quite superficial stuff; even similar bone structure has been proposed as an influential factor in attraction. Where it bleeds into complementarity is when things get more abstract, for example matching life goals tend to correlate with happier relationships (an indicator of attraction).
Why complementarity might be the most important factor at play
The principle of complementarity refers to the hypothesis that the more two people complement each other, the more attractive they will find each other. Now, it’s often confused with similarity because when we talk about more abstract concepts, similarity is often equivalent to complementarity. If you both have the life goal to have kids, for example, then that’s a point of match (similarity) and a complementary goal. Double score on the attraction front.
However, complementarity is NOT always equivalent to similarity. Complementarity is a little more equivocal (see what I did there?). Taking our earlier example, let’s say you both have the life goal to have kids, but also share the life goal to have a successful and high-flying executive career. What you might find is that when you both start getting super-busy, one of you will have to give it up to take care of those kids. Not complementary at all. In fact, the ideal scenario here would be that Mr. or Ms. Imaginary would want to be a stay at home parent while the other sought the high-flying career. That’s complementary.
So, where similarity explains why ‘birds of a feather flock together’, complementarity explains why ‘opposites attract’ (and also why the latter is less common than the former, although so indeed does the concept of fatal attraction). I must emphasise here that when the two concepts go head to head, similarity tends to be the factor that’s most influential in attraction. In fact, when we’re talking about psychological attraction it may be the single most important element. But it seems that while similarity is paramount in those initial stages (and first impressions are crucial, when you start people watching you’ll notice how badly it can go), complementarity is one of the key factors in attraction as the relationships continues. Research has found that complementarity is correlated with greater interpersonal closeness and higher levels of relational closeness.
I’ve actually written before about this with the three ‘needs’ in a relationship. We each seek a different amount of control, intimacy and belonging in a relationship. The complementarity aspect comes in particularly when we talk about control. If one wants lots, and the other wants less, then the relationship tends to go swimmingly.
So birds of a feather might flock together, and opposites attract in some circumstances. But the real key to killer relationships is flexibility.
is it a sin, to be flexible” – Depeche Mode
These four principles affect every relationship you have. Want to get a bit more control? Why don’t you learn about the different kinds of relationships (and the three qualities that determine what kind you have). Or maybe you want to simplify things? Learn the magic number that’ll make any relationship work, according to one of the best psychologists in the business. Giving you the dirt on your search for understanding, psychological freedom and ‘the good life’ at The Dirt Psychology.