I seem to recall somewhere that there was a study which claimed to be able to extract a lot of personal information from a user through their music tastes.

Here is a write-up of that study: http://www.spring.org.uk/2007/02/personality-secrets-in-your-mp3-player.php

I wonder if the same is true of groups.

I think there are a lot of huge unanswered research questions about the functions of groups in a site like Last.fm. While they provide a means for people to cluster and have bounded conversation and, in the case of last.fm, get charts that compile members' listening habits (Belle and Sebastian were this week's top Internet Researchers' band), it seems to me that much of the group activity on Last.fm and Facebook is about identity badges -- a way to mark yourself on your profile, more so than a way to engage others. Anyone know of studies addressing the functions of groups in social network sites? A few months ago Last.fm changed the interface from showing graphic icons of group memberships on personal profiles to listing them in small text. Users really did not like this change. I was not at all surprised as it is so tied to Last.fm identity construction and impression formation. They've made noises about putting images back, but haven't.

By telling Last FM of our music and joining groups we're actually giving Last FM some very rich data about ourselves.

The groups is the least of the information we're giving them, I think. Which is not to say it's not informative. But we're giving them information about what time we listened to every song. If anyone cared to go back and analyze the data, which I assume no one does, all the rhythms of users' daily lives could be reconstructed from the time stamps alone. To say nothing of the information musical taste may convey.

For now though, I'm on a quest to scrobble lots of Queens of the Stone Age.

Which leads to the point that many people seem to game the system, either playing lots of things they want to be seen as listening to whether they're listening or not, or making sure scrobbling is off when they listen to things that don't fit the image they want to project. Nancy