The Expandable Conversation
Here are the results of a little experiment I carried out this afternoon regarding evolving the share list for posts on Google+. I'd been impressed by the potential of the Circles mechanism for sharing things with targeted groups of people, but it had occurred to me that the original audience might not remain the only audience of interest. A casual post can sometimes spawn an insightful conversation that might be of interest to others.
My first attempt, shortly after joining Google+ was to use the post editing feature, in the hope that I could modify the "share list". However the edit UI does not feature the sharing control present in the original posting UI. I then experimented with the reshare function, but doing so loses the comment thread from the original post, which is often contains the motivation for expanding the audience in the first place.
My experiment today involved creating a new circle, then adding people to it after the fact. While this worked, by accident we discovered an even more flexible mechanisms: link mentions
By link mentions, I mean the citing of another Google+ user by the convention of typing + followed by their user name (typically autocompleted for you by the UI) This creates a link to the users profile in the post or comment and
causes them to receive a notification that they have been mentioned. But the most interesting effect is that a user who is link mentioned is added to the share list
if they were not already there.
A user who has been "summoned" to the thread by such means can themselves invite futher participants by mentioning them in turn. And so the conversation grows. A later experiment revealed that disabling the reshare option on a post will not prevent the share list from growing via the link mention mechanism.
Going the other way, it seems that once a user has been mentioned or has posted in a thread, it is difficult or impossible to remove them. Deleting them from the original Circle that was used to share the post will not remove them from the share list if they have made a comment or been mentioned. And even deleting the entire original Circle only seems to remove those members of the Circle who have neither posted or been mentioned.
Of course the original poster retains the ability to moderate comments by deleting them, or reporting abuse. I have not yet found a mechanism by which the OP might "ban" a participant from a thread once they have been added.
Ultimately, I quite like the feature, as it allows conversations on Google+ to grow and expand their reach organically, much as I had originally hoped. It's clear that the clever folks at Google have put some deep thought into making the granular sharing mechanisms both flexible, and discoverable.Thanks to +Random Geek, +Brian Dorsey, +Jon Leitheusser, +Justin Pecott, +Seth Johnson, +Ted Leung and +Dave Peck for their sterling service as guinea pigs.