The evidence is that a contributor who is down-voted produces lower quality content in future that is valued even less by others on the network. What’s more, people are more likely to down-vote others after they have been down voted themselves. The result is a vicious spiral of increasingly negative behaviour that is exactly the opposite of the intended effect.

via Data Mining Reveals How The “Down-Vote” Leads To A Vicious Circle Of Negative Feedback — The Physics arXiv Blog — Medium.