I'm not sure if it's related to what you're wondering, but if it helps clarify anything I'll add that I don't exactly know what a group mind is, or what exactly it means to model a group as one, but that when I ask questions of a forum (or, as in this case, mention to a forum that I'm curious about something) I expect that a large number of individuals will read the question, decide individually whether they have a useful answer and whether they feel like providing it, and act accordingly.

In this case, more specifically, I figured that the people whose voting patterns matched the group-level behavior -- e.g., the ones who upvoted Yvain but not Luke at first, or who downvoted Yvain's request for explanation -- might address my curiosity with personal anecdotes... and potentially that various other people would weigh in with theories.

This is making me wonder if karma can cause people to model LW as having a group mind, and if people generally think of social groups which are too large to model each individual as being group minds.

For my part I model karma interactions and group thinking processes here via subgroups (which are not necessarily mutually exclusive). There are also a few who get their own model - which is either a compliment, insult or in some cases both.