Social interaction cannot be replicated online, but there's still a range among online social media from more atomized and impersonal to more interactive and personal.
The most noticeable trend since the rise of the internet is how far it's moved in the detached and withdrawn direction. This is just the online version of the wider trend toward cocooning, but it's worth noting since the internet could have evolved to serve as a (poor) substitute for real-world gregariousness. Instead people act online more or less the way they do in real life, in this case anyway.
Hardly anyone was connected to the internet before about 1994, when AOL began spreading like mad. Online social media thus all grew up in falling-crime times, but the shift toward cocooning has been gradual. When teenagers first filled those AOL chat rooms, we would talk to anyone about anything. It was like an online version of a corner hang-out, mall food court, etc. There weren't any real divisions of chat rooms by theme, demographic, or anything else. Just a free-for-all, though again most everyone was a middle-class teenager.
Those kind of chat rooms had just about vanished by the late '90s. If you were in a chat room at all, it was probably around a specific theme and only open to a small group who already knew each other online. I don't think any teenagers today spend time in chat rooms of even that narrower type.
As for media that let you interact with people you know in real life, first there was AOL's Instant Messenger. It was released in 1997, and at first it was mostly for messaging people who were online friends. By 1999, it was more common to use it for people you knew in real life, like friends at high school or college. It was more or less like texting, only you had to have computer and internet access.
Already by the early 2000s, people began abusing the "away message" feature, which was probably intended to serve like an answering machine message for when you'd be away from your computer for awhile, though still logged in to IM. Yet it morphed from simple things like "at the library till 5, then dinner at the Max" to the more attention-whoring broadcasts that have become standard in Facebook status updates (more about those in a bit). Although it usually wasn't an obscure rant, but more like a long quote or bit of song lyrics. Either way it made IM a little less personal, knowing that others were using it more and more to tell the world what their favorite quotes were (who cares?).
The next big thing was MySpace, which I actually found more interesting than IM. It was part of that small, brief detour away from the boring and cocooning trend, which I speculated could have been a reaction, not to a rising crime rate, but the similar cause of 9/11. That zeitgeist had gotten started by 2003, peaked during 2004 and '05, was hanging on in '06, and began returning to the longer-term trend sometime in 2007.
You could use MySpace just like IM, sending messages back and forth to people you knew in real life, as well as leave lots of Who Cares? junk littered around your customizable profile. But it was more open than IM because anyone could view anyone else's profile, except for a small number who kept it all private. This admittedly small level of letting your guard down and trusting others online, being willing to disclose at least somewhat personal stuff, was nevertheless unique compared to the longer-term trend toward emotional distance and avoidance.
Sure, some people were a bit too confessional (TMI), but they were only the right tail of the distribution, showing that on average everyone had moved a bit in the more open direction.
By 2006, Facebook began sucking users away from MySpace, and by now has all but killed it off. Since this is around the time when the brief bit of sociability was fading from the zeitgeist, it's interesting to look at the devolution of social interaction on Facebook over the years.
When it started out, Facebook was more insulated than MySpace because you could only see profiles of people in your network (typically a person's high school or college). That was just a small step back toward the cocooning trend. There was still an interactive feel to it, though. Katie posts a message on Dani's wall, Dani replies with a message of her own on Katie's wall, and so on. Not so much the guys, but definitely the girls left "bumper stickers" (funny or sweet pictures) on each others walls just about once a day.
At the start, it was like an avoidant kid's version of exchanging notes through their friends' school lockers. Katie directed each of her messages to particular individuals, received personalized messages in return, and felt free to start a topic of conversation about whatever.
Gradually Facebook profiles have become more and more closed; now you basically have to be in someone's friend list to see their profile. Also the stuff that you might not have known about your acquaintances -- who their favorite author is, what their home town is, their religious views, etc. -- has been relegated to a tab that no one will click on. Before all that stuff was right there on the main profile page, but now it's hidden. I don't know what it is, but people feel like it's snooping to click on their "Info" tab, so that semi-personal story rarely gets shared anymore.
But by far the worst change on Facebook is the shift from exchanging messages with specific individuals to broadcasting a single status update to nobody in particular. Just look at anyone's wall these days -- it's mostly the person talking to themselves through status updates, along with the odd photo that is again being shared to no one specifically.
Originally the status update was like the answering machine message -- "out getting burger king, call my cell if you need me." Now the blank form says, "What's on your mind?" because it's mostly used to blurt out how you hate stupid people on the bus, how this new mango avocado dip is like seriously the sickest thing ever, or whatever else that no one really cares about.
Because these broadcasts aren't directed at specific people, no one of the recipients in the friend list will feel like responding to it. ("Well, it wasn't addressed to me...") Just about everyone ignores them, maybe 2 or 3 people will "like" the update (i.e. want to make it known they agree), and maybe 2 or 3 people will actually respond with a message, although that's only about every other status update. So overall perhaps 1 or 2 people will post a response.
Typically those few who do respond are the same people who respond to all other updates -- they just feel like responding no matter what. So it's not as though a large number of your friends respond to your updates, a handful to this update, another handful to that update, a different handful still to some other update... That's quite a reduction in the range of people you communicate with on Facebook, compared to the days when you only posted messages on each other's walls.
Moreover, the range of conversation topics has now been narrowed to whatever the broadcaster chooses to make a status update about, since that's now the context of most messages you get from others. This move toward egocentrism is off-putting to would-be responders. Not surprisingly, you rarely see spontaneous, unsolicited conversation-starters on people's walls anymore.
Facebook started off as a somewhat more closed version of the anything-goes MySpace, but by now there is virtually no interaction going on. It's just a bunch of atomized people broadcasting their random thoughts that are mostly ignored, occasionally liked, and rarely replied to -- and even then only by the same few reply-happy people. It's hard to believe that they used to use it to exchange messages person-to-person, each conversation having a topical flow of its own.
This is just an impression since I don't have hard data, but from what I see of young people now, it seems like Facebook is taking away more of their time from texting, a very annoying but still more personal way of communicating. Texting co-existed with MySpace and the early Facebook, so what gives? Again I think that was just part of that brief bubble of more sociability during the mid-2000s. Now even texting is too personal and direct, so people are spending less time checking their texts and more time hunched over their laptop to access Facebook, or perhaps using their phones -- but still to use the Facebook app.
The now two-decade-long trend toward social avoidance has gotten so bad that even texting seems quaintly intimate. And the medium that looked like it might offer an online form of gregariousness has instead changed to serve the population's demand for emotional distance and lack of interpersonal attachment, plus a good dose of attention-whoring.
It really makes you wonder what the internet and online social media would have evolved into if they'd been introduced and adopted in the 1960s, '70s, or '80s instead of the '90s and 2000s. But I guess we'll find out when the zeitgeist eventually swings back in the outgoing and fun-loving direction.