Playing hard to get works. We already knew that. But more research confirms the romantic tactic. Potential partners who have an air of mystery are more attractive to men than more attainable mates, a study in the Journal of Consumer Research finds. Researchers showed both shy and smooth men crisp photos of good looking women and blurred pictures of potential dates. "Quite surprisingly, however, the smooth talkers found the date more attractive when the picture was slightly blurry rather than clear," writes researchers Sarah Kim and Aparna A. Labroo. But perhaps even more intriguing about the study is that people like anything that's hard to get--not just ladies. The same study found that shoppers preferred products they had to travel across town to get, even if they could get them closer. So, really, people like anything that's out of reach. But why?

It's all about the chase. There's something sexy about the game. A similar study found that college women were most attracted to male Facebook profiles when they weren't sure if the men liked them at all. "The general assumption is that there is something about the challenge that increases attraction," said study author Erin Whitchurch. If something's just out of your reach, it's fun to try and get it. Once you have it, the object or significant other might not feel as desirable anymore.

You get more than an A for effort. People link good outcomes with trying hard. If you performed well, you likely put in the time and energy to reach your goal. "To get the best outcomes or products, people usually have to expend effort," explain Kim and Labroo. "This relationship between effort and value is so closely associated in a consumer's mind that wanting the best outcomes automatically results in increased preference for any outcome associated with effort, even pointless effort." If you have to work for a lady, or an iPod, it's probably worth it.

Uncertainty is hot. You don't know if the person likes you back, you're not sure you can get the exact item you want in a shop. People like uncertainty. "If you discover that your lottery ticket is a winner, you feel happier when you don't yet know the precise amount of your coming treasure than you do when you instantly learn its value. Or take Christmas: kids (and adults) often enjoy the anticipation of Santa's visit more than the actual presents he brings," explains Time's John Cloud.