It seems like it will play the same song I've heard before even if I downvoted it. Is it trying to figure out what style of music I like during a certain time of day?
I'm the creator of the radio feature so if anyone knows the answer to your question it's me. ;)
First understand that radio was something I wrote in 24 hours. We have a very small team working on listen.grooveshark.com (4 developers including myself) so the time that can be spent on any one thing is pretty limited. So forgive me if it sucks. :P
Grooveshark should not play the same song in the same radio session ever, regardless of your vote. Unfortunately, since all of our content is user sourced, it might be playing different spelling variations of the same song. We try to catch the obvious duplicates but people are very good at misspelling stuff.
We use votes to tweak our recommendations for everyone, but your votes don't currently carry over between radio sessions. Voting will affect the music that gets played currently, but not historically. There are two reasons for this, one being that in order to deal with the volume of play & vote information, it's logged to a place that is good for analyzing in the background but not good for fast lookups. The other is for debugging. If someone complains that radio is doing something weird, it's much harder to figure out why that is if everyone's radio experience is completely unique.
That said, when we have more time/resources I hope we'll be able to make radio smarter. Stay tuned. :)
I don't believe so, as far as I know it just suggests based on the songs already in your queue.