A new survey shows that 90% of people who use the Internet are on at least one social network. And from the billions of photos, tweets, and status updates we post, psychologists are learning a lot about what makes us tick. For example:

• Research shows that online, the average person has 245 friends. That’s about 90 more than we generally have in real life. So, where do those “extra” friends come from? It turns out most of them are people we met through work, through mutual friends, or people we added just because we like how they look.

• Also, social networks are supposed to be about SOCIALIZING, right? Yet a whopping 80% of what we post on Facebook and Twitter is about US – like what we’re doing, eating, or buying. And experts say our “selfishness” extends to our photos, too. Because what’s the first thing a third of us do after posting a photo online? We immediately tag ourselves.

• But here’s the twist: In this new survey, 90% of us said we think people share TOO MUCH online. In fact, half of all Facebook users say they compare themselves to what others are posting. And experts say the more time we spend online, the more we believe that other people have better lives than we do.

So, in a nutshell, what does the psychology of social networking say about us? According to all the researchers at Harvard, Forbes, Consumer Reports, and others who worked on this survey: We’re obsessed with social media, and we’re obsessed with ourselves.