I would think about potentially re-doing the ui to show just one choice in a single page (or make the choice bigger and make it one per row). That way you put a greater focus on actually voting on whatever is in front of you. I just ended up scrolling down the page to see what other stuff was on there and didn't interact at all - I clicked once but the logging in turned me off too. I think you might need to do away with that for voting but perhaps require logging in for adding a comment?
We are going to implement anonymous voting at some point. That's in our pipeline.