Curious.. Do you think it is possible for someone to have an addiction to posting on FB or Tweeting on Twitter? I have heard people say such things like I "spent hours on Facebook and I don't know why?"
A young (~16yo) male relative of mine just spent half a day in my home - in front of his smartphone, to be precise. All the time he'd hit the refresh button and scroll through the same FB news feed again for the 100th time.<p>There is a potentially dangerous feedback effect in social sites imho. Experts will probably better articulate what the trigger is.
I don't think posting or tweeting is addictive, but I do think reading other people's content can be. Myspace was still popular when I was in college and it seemed like half the computer lab I did work in was always on Myspace.