Wisdom of crowd

A team led by Sinan Aral, a network scientist at the Massachusetts Institute of Technology in Cambridge, did exactly that. Aral has been secretly working with a popular website that aggregates news stories. The website allows users to make comments about news stories and vote each other’s comments up or down. The vote tallies are visible as a number next to each comment, and the position of the comments is chronological. (Stories on the site get an average of about ten comments and about three votes per comment.) It’s a follow-up to his experiment using people’s ratings of movies to measure how much individual people influence each other online (answer: a lot). This time, he wanted to know how much the crowd influences the individual, and whether it can be controlled from outside.For five months, every comment submitted by a user randomly received an “up” vote (positive); a “down” vote (negative); or as a control, no vote at all. The team then observed how users rated those comments. The users generated more than 100,000 comments that were viewed more than 10 million times and rated more than 300,000 times by other users

여기서 3가지의 실험을 하였는데 3개의 실험의 명확한 차이가 무엇인가요?

첫번째 실험은 영화의 평점으로 실험한것이고 두번째 실험은 그걸 보완해서 (follow-up)한 실험인데 댓글에 사람들의 댓글에 좋아요와 싫어요를 달게 하고 있어요 이 두실험의 목적은 개개인의 사람들이 각자 서로에게 얼마나 영향을 끼치는지에 대해 알고 싶어하고 그래서 실험결과로서 많이 라는 결과가 나왔고 마지막 세번째 실험의 목적은 군중들이 개개인에게 얼마나 영향을 받는지 혹은 외부에 의해서 통제 받는지 알고 싶어해 여기서 이 첫번째 실험과 두번째 실험 이 두개의 실험과 세번째 실험의 차이가 잘 이해가 안되네요