What Deserves Our Attention?

Every online community has rules that determine how the attention of the community is directed. For example in an online forum, the most up-voted posts may be shown on at the top of the page. This rule concentrates attention on popular content.
But this is a terrible rule. It creates perverse incentives for people to share content that people will reflexively upvote based on first impressions. It encourages shallow conversation on lowbrow topics.