On StackOverflow reputation is subtracted when downvoting answers but not questions [1], which is a neat approach. On your own profile, you can see the proportion of upvotes to downvotes (as well as other activity), but others cannot (maybe moderators?). So, there is at least some personal impact to having a user be accountable for a downvote. There is also generally a culture of "if you downvote, you should explain why", which sometimes seems to be here on HN as well. I remember Disqus removed the downvote count some time back, and Facebook doesn't have a "Dislike" button, so there are different approaches to it. I wonder what some other approaches some communities have taken, and what would be effective? Or even, what is the desired impact?
I'm developing Talkyard which has its own voting system: there's the Like vote, and the Disagree vote.
But the Disagree vote isn't a downvote — it doesn't affect karma or sort order. It justs shows how many people disagree about something. That can be good to know, so one can avoid harmful advice. Or just because one is curious about others' opinions.
There is a downvote too, actually, but only available for staff and core members. It works a bit like the downvote here at HN (e.g. removes "karma" and moves the comment downwards, dims it a bit).
[1]: https://meta.stackoverflow.com/questions/251610/why-does-dow...
[2]: https://disqus.com/home/discussion/supportqa/why_was_the_dow...