One possibility is a weekly msg to the possible offenders. ---e.g.--- You are receiving this msg because SE-VotingSurveyBot has determined that your weekly combined [knee-jerk-voting-Q] (aka BVQ or Biased Voting Quotient) is above xxx -- Your B+VQ (for UpVotes) is yyy which is 5th worst in the site, and your B-VQ (for DownVotes) is zzz which is 3rd worst in the site. Here is a graph of your BVQs in the past year shown along with the average scores in this site.
__________ The ultimate goal of such a measure would be to prevent a snowballing build-up of bias, leading to bullying, hazing, etc.