And neither is your girlfriend, but in order to stomach the prospect of a long-term relationship, you delude yourself into believing she's better looking than she really is. (This has been suspected for so long that even the Greeks had a euphemism for it.)

To see if men (and women) really deceive themselves in this manner, a group of researchers obtained data from the popular physical attractiveness ratings site Hot or Not and studied users' behaviors.

(The researchers: Leonard Lee of Columbia, Dan Ariely of M.I.T., George Loewenstein of Carnegie Mellon and James Hong and Jim Young, the founders of Hot or Not)

The site has evolved to include a dating service dubbed "Meet Me," where instead of rating a person's photo, users pick the photos of the people they're interested in. If both people are open to meeting each other, then the initial contact can be made.

Here are the major findings:

• Men were more open to potential dates than women, by 240 percent.
• Men were also much more generous in their appraisals than women.
• If you were on the receiving end of a request, then the likelihood of accepting increased if other Hot or Not users found the requester to be attractive.
• And if you were deemed attractive by the community, then you were more likely to be picky in saying yes to potential dates. For every point lower you scored on the Hot or Not 1-10 scale, the chances of saying yes to a potential date increased by 25 percent.
• There was no difference between how attractive and unattractive people rated other users.

So the fact that nearly all users are in agreement about who is pretty and not-so-pretty and that, despite this, unattractive people were more open to potential dates than attractive people, lead the researchers to conclude that ugly people who date other ugly people do in fact know the pedigree of their partners.

How do less attractive people cope? In a separate study, the researchers asked 24 participants of an online speed-dating event to complete a short survey in "which they indicated, on a ten-point scale, how much they weighed each of six criteria (physical attractiveness, intelligence, sense of humor, kindness, confidence, and extroversion) when selecting potential dates." After the event, the participants then rated the attractiveness of all those they'd talked to. It turns out that less attractive people put relatively less weight on the physical appearance of potential partners and relatively more weight on other qualities than attractive people do.

Seen from the perspective of hedonic adaptation, the results of both our main and follow-up field studies perhaps highlight one plausible mechanism underlying how people cope with attractive options that are beyond their reach: when faced with a range of options (e.g. potential partners) or life situations (e.g. states of health) of varying hedonic value, instead of adopting a "sour grapes" mindset and deluding themselves that what is unattainable isn't as great as what it looks, people divert their focus to the merits of options that are attainable to them. From an evolutionary perspective, such motivated changes in dating preferences can potentially increase one's pool of potential mates, reducing the likelihood that physically unattractive people will end up without partners, and supporting assortative mating. Much like the famous line from a Crosby, Stills, Nash and Young song, people find a way to love the ones they can be with.

The researchers also unearthed another interesting bit of human behavior. They plotted the likelihood that a user on Hot or Not would say yes to a potential date based on the requester's attractiveness:

Not surprisingly, as the requester became more attractive relative to the requestee, the chances of acceptance increased. But there is a dip once the requester's attractiveness is about 4 points higher than the requestees. This suggests that, even though the hotter person is making the first move, Hot or Not users (and probably all us) are susceptible to the "out-of-my-league" mentality.

Related: An economist solves the mysteries of dating.