On external validation, I wondered about whether a social network or community with a karma system could fake that validation for each user to motivate content creation or positive sentiment?

e.g., if I actually got 5 upvotes on a HN comment, but HN showed it to me as 54, and then 78 and then 104 on subsequent comments, would I be more likely to contribute more? As a new user, would I be drawn in deeper?

It wouldn't work too well with public validation like Twitter, but it could for something like HN (and /. from memory) where the upvote count is now hidden.