"How Community Feedback Shapes Useful Behavior"

This seemed like an interesting piece that was not only right up Lyte's alley, so I hope he can give it a look, but it also suggested implications that were worth taking into account for community beta. Most notably, as BoingBoing highlighted, the study's assessment that "[N]egative feedback leads to significant behavioral changes that are detrimental to the community." Because, "In the case of a negative evaluation however, punishment leads to worse community feedback in the future. More precisely, the difference in the proportion of up-votes received by a user before/after the feedback event is statistically significant at p <0:05."

It brings to mind the question, if the highest voted comments already crown out others and float to the top, what's the point of having downvoting in the system?