I have an idea for a scary story. It could be a movie.

It’s about a large group of people who are captives in a jail where they are monitored constantly and their communications to the outside world are filtered in accordance with the wishes of the captors.

But here’s the big twist: They don’t know they’re in a jail.

Or that they built the jail themselves.

And then, at the moment they realize it, you cut to a wide overhead shot of them all screaming, “Nooooo! Whyyyyy!?” Credits.

It’s possible I’m being a little bit harsh. I’m talking about Facebook. I’ve been on that social network, the one so relevant to our times that a movie about it won three Academy Awards, since 2007. Some experiences in life are like roller coasters, with all the ups and downs, while others are more complex and problematic, like dating a person who seems to love you when they’re not trying to control and destroy you.

I find it both indispensable and scary, basically a public utility that plays by its own rules and is a lot larger than most countries.

But what’s been bothering me about Facebook lately has less to do with how it’s run than how many of its 1.32 billion active users have learned to live on and use Facebook. Two years ago, during the national election season, I wrote about the ways that our political divisions were causing us to use social networks to silo ourselves against opposing opinions and people with different viewpoints, to our detriment.

At the time, I’d hoped it was a symptom of election-year craziness, something that would pass as we all came back together online. But last month, it sure seemed like it was worse than ever. As chaos unfolded in Ferguson, Mo., journalists I’m friends with dutifully posted news reports and links to video live streams on Facebook. African-American friends who aren’t in news posted think pieces and their personal thoughts on the crisis. But by and large, all the other people I’m connected to online, people all over the country and in all kinds of professions from a very diverse set of backgrounds, ignored it.

It was tough to miss every time I got onto the other major social network I frequent, Twitter, where my timeline was dominated by minute-to-minute reports from Ferguson. It wasn’t all good. There was inaccurate reporting, inflammatory out-of-context information, lots of guessing. But people were engaged and it seemed like it was much harder to ignore.

As many pointed out in those tense few weeks, Twitter was the place you went to get an idea of what was happening in Ferguson. Facebook was where you went to see lots of videos of people taking the ALS Ice Bucket Challenge.

Building Facetopia

I think some of that schism has to do with race, class and politics. But I think a larger part of it has to do with the way those of us who spend a lot of time on Facebook have self-curated the service. At a certain point in a Facebook user’s homesteading there, after being aggravated by unwanted video game invites and hateful posts from distant acquaintances, they realize, “Hey, I don’t have to look at this stuff.” The Facebooker begins unfriending undesirables, blocking invites to services or websites they don’t like and building fences around what they see every day.

I call it “Facetopia,” the virtual place we build around our ideals of what we want to see online. In Facetopia, you don’t have to deal with people who disagree with your religious beliefs or debate anyone about who you’re voting for.

In Facetopia, when you post a status update and someone you barely know comes in to disagree with a comment, they get shouted down by all your real friends, the ones who think the way you do.

And Facetopia is reinforced by Facebook’s default setting of “most popular” on its users’ newsfeeds. Instead of displaying the most recent updates Facebook friends are posting, “most popular” shows the Facetopia version of what’s going: the posts that are much-commented-on and well-liked.

The disturbing part of that is that the default setting is where Facebook users cede a lot of control to the social network. If Facebook decides that, along with ads, we should all be reading more about world politics, it wouldn’t be difficult to tweak the newsfeed algorithm to display more about that, less about other stuff.

Facebook should be a place where users can go to relax, while away time with baby photos and have a good time. But the more time we spend there, and the less time we’re exposed to the push and pull of conflicting ideas from the outside world, the more I worry.

Where does that lead? Earlier this year, Facebook bought Oculus VR, a company that makes virtual-reality goggles, for about $2 billion. You can bet that, if Facebook gets it right, we’ll feel the allure of spending even more time in our little Facetopias.

Twittertopia?

Which brings us to a bit of news from last week. It appears that Twitter, which operates in a more real-time way, is looking to take a cue from Facebook by making the feeds of its users similar to the “most popular” approach. By Twitter’s reasoning, users would see less noise in the form of irrelevant Tweets and get higher-quality, curated content by switching from the raw, chronological timeline.

But guess who’s doing the curating?

Twitter users won’t have to build their own Twittertopias. They will be built for them.

And whether that sounds like a scary, oppressive jail or an easier-to-manage paradise really depends on what you want out of social networks. It matters whether you go online to escape or to engage with the world.