You presumably have some evidence that posting a picture to Instagram gives you such a hit, while posting an article to your blog does not. Or at the very least you have some reason to believe this. Could you show it to me? It's going to need to be pretty strong evidence to convince me that blogging, a medium where some posts get a lot of feedback, others a little, and still others none at all, is a system without a variable schedule of rewards.

I agree blogging can count here, when you said journal I thought you meant pen-and-paper private journals.

It doesn't? What about blogging?

Blogging gives the blogger a rewarding experience of being listened to - I wouldn't say that's a trigger, people enjoy being heard, so while they have listeners, they're gonna speak.

The reader on the other hand gets a new post, which could be about anything, and sometimes the post will be bad, other times good, really good. This will create a variable reward system, and keep the reader coming back.

Blogging can definitely be habit forming, especially micro blogging, or, tweeting. I just didn't think that's what he meant.