This question is an exact duplicate of:
Problem: A lot of the time I downvote something that clearly shows lack of research or effort on OP's part, and when they edit to improve it, I usually find out pretty late, because there are no notifications to help with that.
Proposition: add a Get notified when this post is edited button/checkbox under a post which you have downvoted (per post, not just all posts ever), so that if there is a significant improvement, you could remove your downvote or even change it to an upvote to show you recognize the improvement.
I believe this would improve public thinking about votes, and make people (who choose to participate like this on the SE sites more often) vote more freely and more often, and everybody else would not think of a <0 post score as a death sentence for their contribution.
I'm not asking to enable this on SO (for a number of obvious reasons), and that's why I propose an opt-in subscription. This would be most useful on lower activity sites like the SE, in my opinion, but who knows.
I want to know if someone has improved their post after a downvote to reinforce the positive behavior and I get -4 on my good intentions? What kind of culture are you trying to cultivate? Please, explain why you disagree without silently downvoting. If you think there's a better way, yes, I want to know your thoughts.