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In our daily social lives, we're constantly doing things that — on the surface — don't make much sense. We'll pretend we're not interested in someone when we actually have a huge crush on them.

Or we'll tell our friends about a job promotion, but make it sound like no big deal. And all the time, people donate to charities anonymously. To evolutionary biologists, these behaviors are puzzling because usually, if you do something good, you get rewarded for it with a boost to your reputation.

That may not be why you did it, but you still get a nice thing in return. And that's important, because it's how so-called prosocial behaviors get reinforced. But if you hide the fact that you did something good, then, well, all bets are off.

Same thing with trying to find a partner. It usually makes zero sense to hide that you like someone — or to look less attractive by down playing your strengths. And yet, humans are expert concealers.

We love playing hard to get, and we strive for modesty. As natural as these behaviors are, scientists have only recently started to understand them in detail — and in some cases, they're turning to game theory to figure things out. Now, you might be thinking, well, of course we do all this stuff — we don't want to look like narcissistic jerks!

In many cultures, you have to be modest to be considered polite. Numerous studies have even shown that modest people are thought of more positively by others. Well, there are several ideas about why this is.

One suggests that being modest is helpful because you come off as non-threatening. Others suggest that it's all about boosting the self-esteem of the people around you. By not presenting yourself in the most glowing light, you can let them feel superior, and put them in a jolly mood.

You, in turn, end up getting the equivalent of up-votes. So, all in all, modesty is a pretty good tactic in social situations. Still, these ideas don't fully explain things like anonymous donations.

Or, why we pay big bucks for a brand name handbag that has only a very subtle tag on it. That's where the game theory comes in. This year, researchers at Harvard and the Institute of Science and Technology Austria used evolutionary game theory to make sense of these conundrums.

Classical game theory tries to model and understand how people in competition with others make rational decisions. Think war strategy, like figuring out whether to drop a bomb, given what you think your opponent will do in return. Evolutionary game theory is similar, but it doesn't require someone to be making an active decision.

For that reason, it's useful in biology, because scientists can use it to identify tactics that work well for populations — like why peacocks would have evolved such elaborate and showy feathers. But it doesn't have to necessarily be about biological evolution. Social scientists use it, too, to understand how certain behaviors become entrenched.

Like our odd habit of hiding information. In this experiment, the team created what they call a signal-burying game to identify scenarios in which concealment becomes a somewhat common strategy. The game didn't involve any actual people — it was all just a computer simulation.

But it did provide good insights. In it, two virtual people are paired up for an economic interaction. Some are senders, meaning they can send a signal to the other party, if they so choose — a sort of memo announcing how strong of a potential business partner they are.

The other people are receivers, who have varying levels of pickiness in terms of whom they'll partner with. There were a bunch of other details to this, and whether or not a receiver decided to work with a sender ultimately depended on formulas programmed into the game. But the detail that really matters is that the sender didn't have to send an obvious signal about their status.

They also had the option to send a hidden or buried one, which had some chance of being discovered by the receiver — kind of like “accidentally” leaving their resume in the break room. And if it was discovered, the receiver knew it was meant to be a secret. Running the simulation under a variety of conditions, the team learned that signal-burying does appear to be a good strategy in some cases.

Specifically, if there was a good chance that the hidden signal would eventually be noticed, or, if the sender only cared about the picky receivers, it made sense to keep things on the D-L. Essentially, that's because the scientists found that hiding information is itself a signal to others. It can help you come across as more modest, or it can send a message that you aren't interested in what the public thinks — just high-profile individuals.

Take those anonymous donations, for instance. If someone learns through the grapevine who made that huge charity contribution, the fact that it wasn't meant to be public makes it seem that much more noble. Of course, not announcing your donation does mean that far fewer people will know about it.

But maybe it's better for just a handful of powerful people — like the charity, or your closest friends — to know, and to think extra highly of you. Signal-burying might not win you the widespread benefits that usually come with positive behavior — but they might snag you some favor among a select few you especially care about. And that's likely why we keep doing it.

Now, all of this doesn't mean that your choice to downplay your success or conceal a generous donation is always a conscious, plotted-out thing. It could be, but because the researchers used evolutionary game theory, what this really tells us is that hiding stuff has proven to be beneficial, which is why it's spread through society. So, don't feel bad if you naturally do it.

Thanks for watching this episode of SciShow Psych! People do all kinds of weird and fascinating stuff, and if you'd like to learn more, you can check out our episode about self-handicapping — or why you keep sabotaging yourself before that big test. And as always, you can go to youtube.com/scishowpsych and subscribe. [ ♪ OUTRO ].